Topic Editors

Dr. Damian Przestacki
Poznan University of Technology, Faculty of Mechanical Engineering, Faculty of Mechanical Engineering, Institute of Mechanical Technology, ul. Piotrowo 3, 61-138 Poznan, Poland
Prof. Dr. Michal Kulka
Faculty of Materials Engineering and Technical Physics, Institute of Materials Science and Engineering, Poznan University of Technology, ul. Jana Pawła II 24, 60-965 Poznan, Poland
Prof. Dr. Wensheng Li
School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou, China

Laser Surface Modification of Cemented Carbides, Superalloys, Composites, and Alloys

Abstract submission deadline
closed (20 July 2022)
Manuscript submission deadline
closed (20 September 2022)
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Topic Information

Dear Colleagues,

The ongoing demand for more economical, efficient, and reliable products, especially in automotive and aeronautical industries, requires the use of lightweight and modern materials with excellent mechanical properties. Among many advanced manufacturing technologies, laser technologies are of particular importance. This Special Issue deals with all laser technologies as well as the microstructure change of parts and the evaluation of machined surface integrity. Laser technology occupies an important place in engineering production. In many technological processes, it enables one to make a product of the required properties, required dimensional accuracy, and quality of machined surfaces. Laser technology has been established as the key tool for many material processing applications, in many cases providing the unique properties of materials.

This topic aims to present the latest works in the research and development of laser technology applications. The aim of this Special Issue is to present the latest achievements of theoretical and experimental investigations of laser surface modification of different engineering materials. We welcome articles focusing on laser irradiation influence on different kinds of materials such as cemented carbides, superalloys, composites, and alloys. It is our pleasure to invite you to submit a manuscript to this topic. Full papers, communications, and reviews are welcome for submission.

Dr. Damian Przestacki
Prof. Dr. Michal Kulka
Prof. Dr. Wensheng Li
Topic Editors

Keywords

  • functional properties
  • specific forefront scanning-based techniques
  • laser-assisted machining
  • experimental and theoretical approach used in laser technologies
  • specific applications of laser
  • microstructure analysis
  • machining, SEM usage to highlight interaction between different particles
  • advanced applications

Participating Journals

Journal Name Impact Factor CiteScore Launched Year First Decision (median) APC
Materials
materials
3.748 4.7 2008 15.3 Days 2300 CHF
Coatings
coatings
3.236 3.9 2011 14.3 Days 2000 CHF
Metals
metals
2.695 3.8 2011 16 Days 2000 CHF
Solids
solids
- - 2020 16.8 Days 1000 CHF
Quantum Beam Science
qubs
- 3.0 2017 17.8 Days 1600 CHF

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Published Papers (30 papers)

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Article
Effect of Substrates Characteristics on Tribological Behaviors of AlTiN-Based Coated WC–Co Cemented Carbides
Coatings 2022, 12(10), 1517; https://doi.org/10.3390/coatings12101517 - 10 Oct 2022
Abstract
The wear resistance of coated tools is a key technical parameter, which is indirectly affected by the substrate phase characteristics. WC–Co cemented carbides with varied WC grain sizes (0.4, 0.7, 1.2 μm) and Co contents (3, 6, 10, 12 wt.%) were used as [...] Read more.
The wear resistance of coated tools is a key technical parameter, which is indirectly affected by the substrate phase characteristics. WC–Co cemented carbides with varied WC grain sizes (0.4, 0.7, 1.2 μm) and Co contents (3, 6, 10, 12 wt.%) were used as the substrates. Single-layer Al0.52Ti0.48N and multilayer Ti0.89Si0.11N/TiAlSiN/Al0.52Ti0.48N films were deposited on the substrates by DC magnetron sputtering. Reciprocating friction tests were carried out in the air medium and the 3.5 wt.% NaCl aqueous solution, respectively. In the air medium, the films on the fine and the submicron WC–Co substrates with the weaker carrying capacity became worn through earlier than those on the ultrafine substrates. In the NaCl solution medium, for the ultrafine-grained WC–10Co substrates with different Co contents, the friction coefficients (FS) of the film had a linear negative correlation with the hardness (HS) of the substrates. With the decrease in the WC grain sizes or the Co contents, the wear rates of the coated alloys decreased gradually (by 19.7% and 34.5%, respectively). The regular patterns obtained can provide a reference for the selection and design of the phase composition of the cemented carbide substrates. Full article
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Article
Lattice Distortion, Amorphization and Wear Resistance of Carbon-Doped SUS304 by Laser Ablation
Materials 2022, 15(16), 5764; https://doi.org/10.3390/ma15165764 - 20 Aug 2022
Abstract
Lattice distortion and amorphization of carbon-doped SUS304 by variation of the laser output were investigated in terms of phase formation and the bonding state. The laser output was changed by 10% in the range of 60% to 100% after covering the SUS304 with [...] Read more.
Lattice distortion and amorphization of carbon-doped SUS304 by variation of the laser output were investigated in terms of phase formation and the bonding state. The laser output was changed by 10% in the range of 60% to 100% after covering the SUS304 with carbon paste. A graphite peak and expanded austenite (S-phase) peak were observed in the carbon-doped SUS304, and Rietveld refinement was performed to identify the lattice distortion. The lattice constant of SUS304 was initially 3.612 Å, but expansion lattice distortion occurred in the carbon-doped SUS304 as a result of the S phase formation and carbon doping, and the lattice constant increased to 3.964 Å (100% laser output). X-ray photoelectron spectroscopy analysis for the bonding state of the carbon-doped SUS304 showed that the sp2/sp3 ratio decreased from 3.21 (70% laser output) to 2.52 (100% laser output). The residual stress in the lattice was accumulated due to carbon doping by high thermal energy, which resulted in the formation of amorphous carbon. The bonding environment was represented by the ID/IG ratio using Raman analysis, and it increased from 0.55 (70% laser output) to 1.68 (100% laser output). During microstructure analysis of the carbon-doped SUS304, disordered structures by amorphization were observed in the carbon-doped SUS304 by the greater than 90% laser output. The amorphous carbon filled the lattice grains or voids to lubricate the surface, which improved the friction coefficient and wear rate from 0.23 and 7.63 mm3(Nm)−110−6 to 0.09 and 1.43 mm3(Nm)−110−6, respectively. Full article
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Article
Numerical Simulation and Experimental Study on the TIG (A-TIG) Welding of Dissimilar Magnesium Alloys
Materials 2022, 15(14), 4922; https://doi.org/10.3390/ma15144922 - 15 Jul 2022
Abstract
The welding experiments and numerical simulation analysis of dissimilar magnesium alloy AZ61-AM60 were carried out by TIG and A-TIG methods. The mathematical model of welding pool under three-dimensional transient moving heat source has been established, and the temperature field has been numerically simulated. [...] Read more.
The welding experiments and numerical simulation analysis of dissimilar magnesium alloy AZ61-AM60 were carried out by TIG and A-TIG methods. The mathematical model of welding pool under three-dimensional transient moving heat source has been established, and the temperature field has been numerically simulated. The influence of welding process parameters on the surface forming quality of welded joints has been discussed. The simulation results show that temperature field distribution of dissimilar magnesium alloy AZ61-AM60 during the TIG welding process presents a certain asymmetry and the shape distribution of the melting field on both sides of the molten pool is asymmetrical. When A-TIG welding was coated with activating flux, the surface of the molten pool is ingot-shaped. These simulation results are verified through experiment investigation. The consistency between the experimental results and the simulation results reveals the variation law of temperature field and molten pool shape in the welding process, which provides an effective guidance for the optimization of welding process parameters of dissimilar magnesium alloys. Full article
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Article
Failure Analysis of a Chromium Plating Layer on a Piston Rod Surface and the Study of Ni-Based Composite Coating with Nb Addition by Laser Cladding
Metals 2022, 12(7), 1194; https://doi.org/10.3390/met12071194 - 13 Jul 2022
Abstract
The failure of a chromium plating layer on the surface of a piston rod was analyzed, and an Ni-based alloy mixed with a niobium (Nb) composite coating was investigated by means of stereomicroscopy, metallographic microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), [...] Read more.
The failure of a chromium plating layer on the surface of a piston rod was analyzed, and an Ni-based alloy mixed with a niobium (Nb) composite coating was investigated by means of stereomicroscopy, metallographic microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Vickers hardness testing, and wear testing. The results show that penetrating cracks were present in the chromium layer. Subsequently, the corrosion intensified, resulting in the bubbling, cracking, and peeling of the chromium layer. The cladding layer presented a structure morphology of planar crystalline at the bottom, dendritic at the middle, and equiaxial crystalline at the top. The solidification parameters, which were derived from simulation results, confirmed that the ratios between temperature gradient (G) and solidification speed (S) decreased, and the values of the cooling speeds increased from the bottom to the top of the cladding layer. With an increase in Nb content, the structure became gradually refined and uniformly dense. The cladding layer of the Ni-based alloy mixed with Nb was mainly composed of γ-Ni, Cr23C6, Cr7C3, NbC, and Ni3Nb. NbC could be formed in situ and presented itself in four forms: particles, dendrites, polyhedrals, and networks. The microhardness of the coating with 15% added Nb was enhanced to 400 HV0.2, and the wear resistance thereof was 11.14 times higher than the substrate. After the 15% Nb coating had aged for 16 h, the diffraction peak intensities of Cr23C6 and Cr7C3 significantly increased, and the volume fraction of granular NbC increased from 1.67% to 2.54%. The microhardness was enhanced to 580 HV0.2, and the wear resistance thereof was better than that of the chromium plating layer. Full article
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Article
Multi-Objective Optimization of Process Parameters of 45 Steel Laser Cladding Ni60PTA Alloy Powder
Coatings 2022, 12(7), 939; https://doi.org/10.3390/coatings12070939 - 01 Jul 2022
Abstract
When laser cladding is used to repair parts, the interaction of parameters has a significant influence on equipment performance. In order to explore the process parameters and quality of Ni60PTA coating, the statistical relationship between the process parameters (laser power, scanning speed, and [...] Read more.
When laser cladding is used to repair parts, the interaction of parameters has a significant influence on equipment performance. In order to explore the process parameters and quality of Ni60PTA coating, the statistical relationship between the process parameters (laser power, scanning speed, and powder feeding rate) and the responses (dilution ratio, ratio of layer width to height, and contact angle) was established by experiments using the response surface method (RSM) and variance analysis. The results show that the laser power is the dominant factor affecting the dilution ratio. However, the scanning speed has the greatest influence on the ratio of layer width to height and contact angle. These experimental results show that the proposed model can predict the actual data. In addition, the microstructure and microhardness of the samples prepared with the optimum process parameters were characterized. The results show that the quality of the cladding layer is good without cracks, deformation, and pores. The microstructure of the cladding zone is mainly composed of γ (Ni), FeNi3, M (M = Fe, Ni, Cr)23C6, M7C3, and CrB. The average microhardness of the coating is about 620 HV0.2, which is about 3.1 times that of 45 steel substrate. Full article
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Article
Microstructure and Tribological Properties of Lubricating-Reinforcing Laser Cladding Composite Coating with the Ti2SC-Ti2Ni Mosaic Structure Phase
Coatings 2022, 12(7), 876; https://doi.org/10.3390/coatings12070876 - 21 Jun 2022
Cited by 1
Abstract
Lubricating-reinforcing composite coatings were successfully prepared on Ti6Al4V using laser-clad Ti6Al4V/Ni60/Ni-MoS2 mixed powders with different Ni-MoS2 contents (25, 35, and 45 wt.%), and their microstructure and tribological properties were studied. The reinforcing phase TiC, Ti2Ni, and the lubricating phase [...] Read more.
Lubricating-reinforcing composite coatings were successfully prepared on Ti6Al4V using laser-clad Ti6Al4V/Ni60/Ni-MoS2 mixed powders with different Ni-MoS2 contents (25, 35, and 45 wt.%), and their microstructure and tribological properties were studied. The reinforcing phase TiC, Ti2Ni, and the lubricating phase Ti2SC were in situ precipitated while Ti2SC and Ti2Ni formed a mosaic coherent structure within the above three coatings. In the 25 and 45 wt.% Ni-MoS2 coatings, the microstructure distribution uniformity of the coatings was not effectively improved by the Ti2SC-Ti2Ni mosaic structure phase due to the lower or higher content of Ti2SC. In the 35 wt.% Ni-MoS2 coating, the forming quality of the coating was the best due to an appropriate amount of the uniformly distributed Ti2SC-Ti2Ni mosaic structure phase. Furthermore, the microhardness of the coatings gradually decreased as the amount of Ni-MoS2 increased. In the 35 wt.% Ni-MoS2 coating, due to the uniformly and diffusely distributed Ti2SC-Ti2Ni mosaic structure phase, the stable lubricating-reinforcing mosaic structure transfer composite films were formed during the progress of the friction and wear tests, which led to the optimal worn surface evenness and quality, the anti-friction and the wear resistance properties compared with the Ti6Al4V, 25 and 45 wt.% Ni-MoS2 coating. Full article
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Article
Study of the Mechanical Properties and Microstructural Response with Laser Shock Peening on 40CrMo Steel
Metals 2022, 12(6), 1034; https://doi.org/10.3390/met12061034 - 17 Jun 2022
Cited by 1
Abstract
In this work, the purpose of the study was to explore the influence of laser shock peening (LSP) on the mechanical behavior and microstructural response of 40CrMo steel. The residual stress at depth direction and the microstructural evolution of 40CrMo steel specimens without [...] Read more.
In this work, the purpose of the study was to explore the influence of laser shock peening (LSP) on the mechanical behavior and microstructural response of 40CrMo steel. The residual stress at depth direction and the microstructural evolution of 40CrMo steel specimens without and with LSP treatments were tested by residual stress tester and transmission electron microscopy (TEM). The microhardness at depth direction and the tensile properties at room temperature were measured. Moreover, the effects of LSP on the ability to resist wear of 40CrMo steel were analyzed, and the worn morphologies characteristics were observed by scanning electron microscope (SEM). The results demonstrated that LSP led to the surface residual stress convert from tensile stress to compressive stress, while the surface compressive residual stress tested parallel to the laser path of the specimen subjected to LSP reached −425 MPa. After the LSP process, the average surface microhardness reached 338 HV, which increased by 21.58% than that of the untreated sample. LSP could enhance the strength without losing plasticity significantly, while the average tensile strength reached 1165 MPa, and the fracture elongation reached 13.9%. After a friction and wear test, the mass loss of the sample after LSP treatment reduced by 27.5% compared to the original sample. The increase in dislocation density and the formation of deformation twins generated by LSP played a key role in enhancing the mechanical behavior of 40CrMo steel. Full article
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Article
Effect of Preheating Temperature on Geometry and Mechanical Properties of Laser Cladding-Based Stellite 6/WC Coating
Materials 2022, 15(11), 3952; https://doi.org/10.3390/ma15113952 - 01 Jun 2022
Cited by 3
Abstract
The effect of 60Si2Mn substrate preheating on the forming quality and mechanical properties of cobalt-based tungsten carbide composite coating was investigated. Substrate preheating was divided into four classes (room temperature, 150 °C, 250 °C, and 350 °C). The morphology, microstructure, and distribution of [...] Read more.
The effect of 60Si2Mn substrate preheating on the forming quality and mechanical properties of cobalt-based tungsten carbide composite coating was investigated. Substrate preheating was divided into four classes (room temperature, 150 °C, 250 °C, and 350 °C). The morphology, microstructure, and distribution of elements of the coating were analyzed using a two-color laser handheld 3D scanner, a scanning electron microscope (SEM), and an energy dispersive X-ray spectrometer (EDX), respectively. The hardness and wear properties of the cladding layer were characterized through a microhardness tester and a friction wear experiment. The research results show that the substrate preheating temperature is directly proportional to the height of the composite coating. The solidification characteristics of the Stellite 6/WC cladding layer structure are not obviously changed at substrate preheating temperatures of room temperature, 150 °C, and 250 °C. The solidified structure is even more complex at a substrate preheating temperature of 350 °C. At this moment, the microstructure of the cladding layer is mainly various blocky, petaloid, and flower-like precipitates. The hardness and wear properties of the cladding layer are optimal at a substrate preheating temperature of 350 °C in terms of mechanical properties. Full article
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Article
Study on Microstructure and Properties of Nickel-Based Self-Lubricating Coating by Laser Cladding
Coatings 2022, 12(6), 753; https://doi.org/10.3390/coatings12060753 - 31 May 2022
Cited by 1
Abstract
Ni35 + 20% SiC + 20% Ni/MoS2 self-lubricating coatings were fabricated on a grade 45 steel surface by laser cladding to obtain better comprehensive performance of wear resistance and corrosion resistance. The macroscopic morphology, microstructure, microhardness, phase composition, corrosion resistance and wear [...] Read more.
Ni35 + 20% SiC + 20% Ni/MoS2 self-lubricating coatings were fabricated on a grade 45 steel surface by laser cladding to obtain better comprehensive performance of wear resistance and corrosion resistance. The macroscopic morphology, microstructure, microhardness, phase composition, corrosion resistance and wear resistance of the coatings were investigated. The results show that the microstructure of the cladding layer is dense, mainly composed of cellular crystal and equiaxed crystal; The average microhardness of the coating is about 700 HV; The phase composition of the coating mainly includes Ni-Cr-Fe solid solution and metal sulfide, such as MoS2, NiS, Cr2S3, and CrMo3S4; Under the simulated seawater environment of 3.5% NaCl, the self-corrosion potential is 0.052 V and the self-corrosion current density is 1.69 × 10−5 A∙cm2. Compared with grade 45 steel, the corrosion resistance is greatly improved; After 20 min of wear, the weight loss of the cladding layer is about 0.17 times that of the grade 45 steel, the friction coefficient is small, and the wear resistance is significantly improved. Full article
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Article
Microstructure and Wear Resistance of Fe60 Laser Cladding Coating Assisted by Steady Magnetic Field–Mechanical Vibration Coupling Field
Coatings 2022, 12(6), 751; https://doi.org/10.3390/coatings12060751 - 31 May 2022
Cited by 1
Abstract
Fe60 laser cladding coating was prepared on the surface of 45 steel with the assistance of alternating magnetic field–mechanical vibration coupling field. The XRD results show that the coating is mainly composed of solid solution Ni-Cr-Fe, (Fe, Ni), and Fe-Cr and also contains [...] Read more.
Fe60 laser cladding coating was prepared on the surface of 45 steel with the assistance of alternating magnetic field–mechanical vibration coupling field. The XRD results show that the coating is mainly composed of solid solution Ni-Cr-Fe, (Fe, Ni), and Fe-Cr and also contains a certain amount of Cr2Fe14C hard phase. In the process of laser cladding, the chemical composition of the coating is not affected by the coupling field. Under the interaction of the coupling field, the liquid metal in the molten pool is fully stirred; the heat diffusion in the molten pool is accelerated; the temperature gradient in front of the solid–liquid interface decreases; and the large-size dendrites are broken. Those contribute to the grains being refined significantly in the coating. In addition, the content of Cr2Fe14C hard phase in the coating is increased under the coupling field. The maximum microhardness of the coating can reach 702 HV0.2, and the corrosion rate of the coating is the lowest under the coupling field, while the weight loss of the 45 steel surface with the action of the coupling field is 68.9% lower than that without coupling field. The laser cladding technology assisted by alternating magnetic field–mechanical vibration coupling field can promote the development of a wear-resistant coating field. Full article
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Article
Effects of Diatomite Contents on Microstructure, Microhardness, Bioactivity and Biocompatibility of Gradient Bioceramic Coating Prepared by Laser Cladding
Metals 2022, 12(6), 931; https://doi.org/10.3390/met12060931 - 28 May 2022
Cited by 1
Abstract
Biometallic materials are widely used in medicine because of excellent mechanical properties. However, biometallic materials are limited in the application of biomaterials due to their lack of bioactivity. To solve this problem, a gradient bioceramic coating doped with diatomite (DE) was successfully fabricated [...] Read more.
Biometallic materials are widely used in medicine because of excellent mechanical properties. However, biometallic materials are limited in the application of biomaterials due to their lack of bioactivity. To solve this problem, a gradient bioceramic coating doped with diatomite (DE) was successfully fabricated on the surface of Ti6Al4V alloy by using the broadband-laser cladding process to improve the bioactivity of metal materials. As well as the DE contents on the microstructure, microhardness, bioactivity and biocompatibility were investigated. The experimental results demonstrate that the addition of moderate amounts of DE is effective in reducing the number of cracks. The X-ray diffraction (XRD) results reveal that the bioceramic coating doped with DE mainly consists of CaTiO3, hydroxyapatite (HA), tricalcium phosphate (TCP) and silicate, and that the amount of HA and TCP in the coating reached maximum when the bioceramic coating was doped with 10wt% DE. The bioceramic coating doped with 10wt% DE has favorable ability to deposit bone-like apatite. These results indicate that the addition of DE can improve cracking sensibility, bioactivity and biocompatibility of the coating. Full article
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Article
High-Temperature Corrosion of Ni-Cr-Mo Cladding Layers with Different Si Contents in NaCl-KCl-Na2SO4-K2SO4 Mixed Salt Medium
Materials 2022, 15(9), 3152; https://doi.org/10.3390/ma15093152 - 27 Apr 2022
Abstract
In this work, Ni-Cr-Mo cladding layers with different Si contents were prepared on Q235 steel using laser-cladding technology, and their corrosion characteristics were investigated in NaCl-KCl-Na2SO4-K2SO4 mixed salt at 550 °C. The corrosion resistance of each [...] Read more.
In this work, Ni-Cr-Mo cladding layers with different Si contents were prepared on Q235 steel using laser-cladding technology, and their corrosion characteristics were investigated in NaCl-KCl-Na2SO4-K2SO4 mixed salt at 550 °C. The corrosion resistance of each cladding layer was tested by weight loss method, and the phase compositions and microstructures of the cladding layers and corrosion products were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that Si contributed to the formation of a dense chromium oxide film on the surface, and the addition of Si can significantly improve the corrosion resistance of the cladding layer at high temperature. At 550 °C, the corrosion rate of the cladding layer with 5 wt.% Si was only 38.2% of that of the cladding layer without Si. After 168 h of high-temperature corrosion, no Cr-rich oxide scale was found in the outermost layer of the Ni-Cr-Mo cladding layer without Si. When Si content was 3 wt.% and 5 wt.%, the Cr-rich oxide scale of the cladding layer was denser than that of the coating with 1 wt.% Si content. Full article
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Article
Study on the Cutting Performance of CrN/AlCrN-Coated Carbide PCB Milling Cutter
Coatings 2022, 12(5), 556; https://doi.org/10.3390/coatings12050556 - 20 Apr 2022
Cited by 3
Abstract
A CrN/AlCrN coating was prepared on a carbide substrate and PCB milling cutter by the cathodic arc ion plating technique. The organization, mechanical and tribological properties of the coating were studied. The milling performance of the coated milling cutters was investigated by milling [...] Read more.
A CrN/AlCrN coating was prepared on a carbide substrate and PCB milling cutter by the cathodic arc ion plating technique. The organization, mechanical and tribological properties of the coating were studied. The milling performance of the coated milling cutters was investigated by milling tests. The results show that the surface of the CrN/AlCrN coating is smooth and dense without obvious defects. The coating has high hardness, low roughness and good bonding strength, presenting excellent mechanical properties. The coating showed better tribological performance and a lower friction coefficient under low load than that under high load, and the wear forms were adhesive wear and a small amount of oxidation wear. The coated milling cutters showed excellent milling performance when working at lower feed rates. The service life of coated milling cutters is significantly higher compared to uncoated cutters. Full article
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Article
Laser Surface Melting and Consecutive Point-Mode Forging Hardening of DH36 Marine Steel: Mechanical and Precipitation Behavior
Coatings 2022, 12(4), 495; https://doi.org/10.3390/coatings12040495 - 07 Apr 2022
Cited by 1
Abstract
This study investigates the effect of the laser surface melting and consecutive point-mode forging process (LSM-CPF) on the mechanical properties and the microstructure of DH36 marine steel. The microstructual revolution during the LSM-CPF process are revealed by metallographic microscope (OM) and scanning electron [...] Read more.
This study investigates the effect of the laser surface melting and consecutive point-mode forging process (LSM-CPF) on the mechanical properties and the microstructure of DH36 marine steel. The microstructual revolution during the LSM-CPF process are revealed by metallographic microscope (OM) and scanning electron microscope (SEM) technique, and the strengthening mechanisms for different samples are also elucidated. The results show that the best yield strength (σ0.2) and tensile strength (σb) for the sample treated with 4000 W laser power and 10% reduction ratio are 721.3 and 884.2 MPa, which are 49.55% and 41.54% higher than that of the DH36 matrix, respectively. The hardness of the coatings decreases along the normal direction with the maximum value of 586.4 HV in the CPF zone for the sample treated with 2000 W laser power and 20% reduction ratio. During the low power LSM-CPF treatment, the nanoscale cementite appear as intragranular due to the inhibited carbon diffusion. The coherent boundary of (110)NbC‖(110)Ferrite, [11¯0]NbC‖[001]Ferrite between NbC and ferrite reduces the nucleation barrier to promote the nucleation of acicular ferrite (AF). The strengthening mechanism for samples treated at 2000 W is found to be dislocation strengthening. During high power laser treatment, pearlite transformation is found to occur with a low cooling rate. In this case, the strengthening mechanism is the boundary strengthening of lamellar pearlite and dislocation strengthening. Full article
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Article
Surface Modification of Titanium by Femtosecond Laser in Reducing Bacterial Colonization
Coatings 2022, 12(3), 414; https://doi.org/10.3390/coatings12030414 - 20 Mar 2022
Cited by 3
Abstract
In the past few decades, titanium and its alloys have been widely used in the orthopaedic field. However, because titanium is bioinert and lacks antibacterial properties, infection may happen when bacteria attach to implant surfaces and form biofilms. It has been studied that [...] Read more.
In the past few decades, titanium and its alloys have been widely used in the orthopaedic field. However, because titanium is bioinert and lacks antibacterial properties, infection may happen when bacteria attach to implant surfaces and form biofilms. It has been studied that some naturally existing micron-scale topographies can reduce bacterial attachment such as cicada wings and gecko skins. The aim of this in vitro study was to find an implant with good biocompatibility and antimicrobial properties by the modification of micron-scale topographies. In this paper, a femtosecond laser was used to provide microtopography coatings on Ti substrates. The surface morphology of Ti substrates was observed by scanning electron microscopy (SEM). XPS was used to fulfil the chemical compositional analysis. The surface wettability was measured by contact angle measurement system. The effect of microtopography coatings with different surface microstructures on bacterial activities and bone marrow mesenchymal stem cells (BMSC) functions was investigated. The results of in vitro study revealed that microtopography coatings restrain the adhesion of Staphylococcus aureus (S. aureus) and Staphylococcus epidermidis (S. epidermidis), which are common pathogens of orthopaedic implant infections. In addition, microtopography coatings stimulated BMSC adhesion and proliferation. Our studies suggest that a microtopography-coated sample modified by femtosecond laser showed promising antibacterial properties and favourable biocompatibility. The femtosecond laser technique provides an accurate and valid way to produce microtopography coatings with outstanding biocompatibility and antimicrobial properties, and could be widely used to modify the surface of orthopaedic metal implants with great potential. Full article
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Article
Microstructure and Wear Properties of IN718/WC Composite Coating Fabricated by Ultrasonic Vibration-Assisted Laser Cladding
Coatings 2022, 12(3), 412; https://doi.org/10.3390/coatings12030412 - 20 Mar 2022
Cited by 1
Abstract
Laser cladding coating with wolfram carbide (WC) as enhanced particles can improve the performance of nickel-based materials. However, there still exists several problems, such as serious element segregation and unequal distribution of the reinforcement phase. In order to improve the mechanical properties further, [...] Read more.
Laser cladding coating with wolfram carbide (WC) as enhanced particles can improve the performance of nickel-based materials. However, there still exists several problems, such as serious element segregation and unequal distribution of the reinforcement phase. In order to improve the mechanical properties further, IN718/WC coatings were prepared by ultrasonic vibration-assisted laser cladding. The effects of ultrasonic vibration on the ceramic distribution, microstructure, and wear performance were systematically studied. The results show that ultrasonic vibration can promote the uniform distribution of WC particles without changing the phase composition of the coating. The cavitation and acoustic flow induced by ultrasonic vibration interrupt the growth of columnar dendrites and refine the grains. In addition, the microhardness of the ultrasonic vibration-assisted coating is enhanced by 15.6% to 475 HV0.2. The average coefficient of friction (COF) of the ultrasonic vibration-assisted coating is 0.452, which is 17.5% lower than that of the unassisted coating. The wear volume of the coating is decreased significantly, and the wear characteristics change from severe adhesive wear to the slight coexistence of abrasive wear and adhesive wear. Full article
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Article
On-Demand Wettability via Combining fs Laser Surface Structuring and Thermal Post-Treatment
Materials 2022, 15(6), 2141; https://doi.org/10.3390/ma15062141 - 14 Mar 2022
Cited by 1
Abstract
Laser surface texturing (LST) is one of the surface modification methods that increase or provide new abilities for the material surface. Textured surfaces could be applied in different industrial areas to reduce wear and friction, promote anti-fouling, improve osseointegration, and other similar uses. [...] Read more.
Laser surface texturing (LST) is one of the surface modification methods that increase or provide new abilities for the material surface. Textured surfaces could be applied in different industrial areas to reduce wear and friction, promote anti-fouling, improve osseointegration, and other similar uses. However, LST is still in development and for reaching industrial level further optimization is required. In this paper, different metal alloy surfaces were fabricated with several patterns using the same laser parameters on each material and the results were compared. This could lead to possible optimization on the industrial level. Furthermore, research on the wettability properties of material and texture patterns depending on heat treatment in different temperatures was performed, showing complete control for wettability (from hydrophilic to hydrophobic). Full article
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Article
Preparation and Study on Fretting Tribological Behavior of Composite Lubrication Structure on the Titanium Alloy Surface
Coatings 2022, 12(3), 332; https://doi.org/10.3390/coatings12030332 - 03 Mar 2022
Cited by 3
Abstract
As an excellent light metal material, titanium alloy has an important application in high technology equipment. In this study, the composite lubrication structure was prepared on the titanium alloy surface by combining the surface texture, thermal oxidation layer, and polytetrafluoroethylene (PTFE)-based lubricating coating. [...] Read more.
As an excellent light metal material, titanium alloy has an important application in high technology equipment. In this study, the composite lubrication structure was prepared on the titanium alloy surface by combining the surface texture, thermal oxidation layer, and polytetrafluoroethylene (PTFE)-based lubricating coating. The effect of texture parameters and thermal oxidation layer on the fretting wear behavior of the composite lubrication structure was evaluated under a load of 50 N. The results showed that the PTFE-based lubricating coating on the textured surface showed excellent friction-reduction and anti-wear effect compared with the coating on the single smooth surface and thermal oxidation surface. The introduction of a thermal oxidation layer on the textured surface further improved the fretting wear life of lubrication coating. The friction coefficient and wear rate can be as low as 0.242 and 2.3 × 10−5 mm3·N−1m−1, respectively, under dry fretting contact conditions. Compared with the untextured surface, the longevity of the composite lubrication structure is extended by more than 90%. Full article
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Article
Influences of Pulse Shaping on Single-Track Clad of AISI316L Stainless Steel by Laser Material Deposition
Coatings 2022, 12(2), 248; https://doi.org/10.3390/coatings12020248 - 14 Feb 2022
Cited by 2
Abstract
As a very common type of laser additive manufacturing technology, laser material deposition (LMD) is widely used, having exceptional application advantages including surface enhancing, repairing damaged parts with high value-add, and building functionally graded material. At present, the continuous wave laser is a [...] Read more.
As a very common type of laser additive manufacturing technology, laser material deposition (LMD) is widely used, having exceptional application advantages including surface enhancing, repairing damaged parts with high value-add, and building functionally graded material. At present, the continuous wave laser is a common laser mode used in the LMD process. The investigation of pulse shaping, which can add a degree of control over the thermal history, is limited. In this study, the effects of pulse shaping on the geometrical characteristics, microstructure, and microhardness were investigated through conducting single-track experiments with different laser shapes, including continuous, rectangular, ramp up, ramp down, and hybrid ramp. The results indicated that the clads created by continuous and ramp up laser shape presented the maximum and minimum dimensions of geometrical characteristics, respectively. The rectangular and hybrid ramp laser shape deposited the clads with similar dimensions. The continuous laser shape produced the clad with the coarsest microstructure and lowest hardness because of the lowest cooling rate. The smallest grain size and highest hardness presented in the clad were seen with the rectangular laser shape owing to the biggest cooling rate. The cooling rates in ramp up and ramp down were restrained by the gradual heating and gradual cooling, respectively. Full article
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Article
Preparation and Enhanced Isothermal Oxidation Resistance of a Low Diffusivity NiRePtAl Single-Phase Coating
Coatings 2022, 12(2), 114; https://doi.org/10.3390/coatings12020114 - 20 Jan 2022
Abstract
A low diffusivity NiRePtAl single-phase coating was formed on a Ni3Al-based SC superalloy by electroplating and aluminizing treatments, in which the electroplating consisted of depositing Ni-Re and Pt layer. The isothermal oxidation test of the sample was evaluated at 1100 and [...] Read more.
A low diffusivity NiRePtAl single-phase coating was formed on a Ni3Al-based SC superalloy by electroplating and aluminizing treatments, in which the electroplating consisted of depositing Ni-Re and Pt layer. The isothermal oxidation test of the sample was evaluated at 1100 and 1200 °C; the results indicated that the low diffusivity NiRePtAl single-phase sample promoted the oxidation resistance due to a greater β-NiAl phases-enriched outer layer. The Re-base diffusion barrier could effectively refrain the outward diffusion of Mo. Low diffusivity NiRePtAl single-phase coating has a lower inter-diffusion rate to the superalloy, where the thickness of the secondary reaction zone decreased by 35%. Mechanisms responsible for improved oxidation resistance and decreased extent for the formation of secondary reaction zones are discussed in the present study. Full article
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Article
Isothermal Oxidation TGO Growth Behaviors of Laser-Remolten LZO/YSZ Thermal Barrier Coatings
Coatings 2022, 12(2), 107; https://doi.org/10.3390/coatings12020107 - 18 Jan 2022
Cited by 1
Abstract
Laser scanning modification was applied to secondarily melt the top ceramic coating surface of lanthanum zirconate/yttria-stabilized zirconia double ceramic thermal barrier coatings (LZO/YSZ TBCs) to reduce the gas oxygen diffusion and improve the TBCs service life. Isothermal oxidations with different times were carried [...] Read more.
Laser scanning modification was applied to secondarily melt the top ceramic coating surface of lanthanum zirconate/yttria-stabilized zirconia double ceramic thermal barrier coatings (LZO/YSZ TBCs) to reduce the gas oxygen diffusion and improve the TBCs service life. Isothermal oxidations with different times were carried out on the as-sprayed (AS) TBCs and laser-remolten (LR) TBCs at 1100 °C to investigate thermally growth oxide (TGO)growth mechanisms and isothermal oxidation behaviors. The results showed that the laser-remolten top-ceramic-coating dense layer with a columnar crystal structure of LR TBCs presented a 96.3% and 59.1% lower surface roughness and porosity, respectively, than those of the top ceramic coating of AS TBCs, and the TGO growth rate of LR TBCs decreased by 46.2% compared to that of AS TBCs. The mixed-oxides appearance time of LR TBCs (50 h) was later than that of AS TBCs (25 h). After 100 h of isothermal oxidation, the total TGO thickness of LR TBCs was only 77.2% of that of AS TBCs, and the effects of the laser-remolten TBCs on gas oxygen diffusion inhibition and high-temperature oxidation resistance were promising in LZO/YSZ TBCs. Full article
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Article
Microstructure and Wear Resistance of a Cr7C3 Reinforced Ni3Al Composite Coating Prepared by Laser Cladding
Coatings 2022, 12(1), 105; https://doi.org/10.3390/coatings12010105 - 17 Jan 2022
Cited by 1
Abstract
Using Cr7C3/Ni3Al alloyed powder and Cr3C2/Ni3Al mixed powder, laser cladding was carried out to prepare a Cr7C3 reinforced Ni3Al composite cladding layer. The microstructure and tribological [...] Read more.
Using Cr7C3/Ni3Al alloyed powder and Cr3C2/Ni3Al mixed powder, laser cladding was carried out to prepare a Cr7C3 reinforced Ni3Al composite cladding layer. The microstructure and tribological properties of the cladding materials were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and wear tests. The results indicate that the microstructure of the Cr7C3/Ni3Al alloyed powder cladding layer contains mainly Ni3Al, NiAl, and in situ-formed Cr7C3, whereas Cr3C2 occurs in the Cr3C2/Ni3Al mixed powder cladding layer. The friction coefficient and wear loss of the alloyed powder cladding layer are about 0.1 and 0.75 mg, respectively, which are less than those of the mixed powder cladding layer (0.12 and 0.8 mg). Moreover, the alloyed powder cladding layer is much friendlier to its counterpart. The counterpart’s loss weight of the alloyed powder cladding layer decreases 42.2% than the mixed powder cladding layer. The reason can be attributed to the homogeneous distribution of fine in situ-formed Cr7C3 in the alloyed powder cladding materials, which can effectively separate the friction pair, improving the wear resistance of the cladding materials. Full article
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Article
Microstructure and Mechanical Properties of TiC/TiB Composite Ceramic Coatings In-Situ Synthesized by Ultrasonic Vibration-Assisted Laser Cladding
Coatings 2022, 12(1), 99; https://doi.org/10.3390/coatings12010099 - 15 Jan 2022
Cited by 1
Abstract
Laser cladding coating has many advantages in surface modification, such as a small heat-affected zone, and good metallurgical bonding. However, some serious problems such as pores, and poor forming quality still exist in the coating. To suppress these problems, a novel process of [...] Read more.
Laser cladding coating has many advantages in surface modification, such as a small heat-affected zone, and good metallurgical bonding. However, some serious problems such as pores, and poor forming quality still exist in the coating. To suppress these problems, a novel process of ultrasonic vibration-assisted laser cladding process was adopted to in-situ synthesize TiC/TiB composite ceramic coating on the surface of titanium alloy. Results showed that the introduction of ultrasonic vibration effectively improved the surface topography of the coating, reduced the number of pores in the coating, refined the crystal grains of the coating, decreased the residual tensile stress in the coating, and increased the micro-hardness of the coating. The tribological properties of the coating were significantly improved by the ultrasonic vibration, the wear resistance of the coating fabricated with ultrasonic vibration at power of 400 W increased about 1.2 times compared with the coating fabricated without ultrasonic vibration, and the friction coefficient decreased by 50%. Full article
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Article
Study on the Solidification Behavior of Inconel617 Electron Beam Cladding NiCoCrAlY: Numerical and Experimental Simulation
Coatings 2022, 12(1), 58; https://doi.org/10.3390/coatings12010058 - 05 Jan 2022
Abstract
To better control the Inconel617 electron beam cladding solidification process, a three-dimensional temperature field model was built to simulate the temperature gradient, cooling rate, and solidification rate in the solidification process and take a deep dive into the solidification behavior, as well as [...] Read more.
To better control the Inconel617 electron beam cladding solidification process, a three-dimensional temperature field model was built to simulate the temperature gradient, cooling rate, and solidification rate in the solidification process and take a deep dive into the solidification behavior, as well as the calculation of the solidification characteristic parameters at the edge of the molten pool and then predict the solidification tissue structure. The study shows that the largest temperature gradient occurred in the material thickness direction. The self-cooling effect of the material dominated the solidification of the alloy layer; the cooling rate depended on the high-temperature thermal conductivity of the material and the self-cooling effect of the matrix, and the maximum cooling rate in the bonding zone was 1380 °C/s. The steady-state solidification rate was equal to the moving speed of the heat source; the solidification characteristics of the solidification process at the edge of the molten pool increased with the distance from the surface: the cooling rate decreased from 1421.61 to 623 °C/s, the temperature gradient increased from 0.0723 × 106 to 0.417 × 106, and the solidification rate decreased from 0.01 to 0 m/s. The prediction was made that the small and thin equiaxed crystals are on the top, a thin and short dendritic transition structure in the middle, and relatively coarse dendrites at the bottom. Experiments confirmed that the solidification tissue structure is basically consistent with the simulation law. Full article
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Article
Laser Texturing for Superwetting Titanium Alloy and Investigation of Its Erosion Resistance
Coatings 2021, 11(12), 1547; https://doi.org/10.3390/coatings11121547 - 16 Dec 2021
Cited by 9
Abstract
Erosion of materials is one of the major causes that lead to the malfunction of equipment and facilities, and surface texturing can be a solution for enhancement of erosion resistance. In this work, superwetting (superhydrophilic/superhydrophobic) titanium (Ti) alloy surface with periodic microstructure was [...] Read more.
Erosion of materials is one of the major causes that lead to the malfunction of equipment and facilities, and surface texturing can be a solution for enhancement of erosion resistance. In this work, superwetting (superhydrophilic/superhydrophobic) titanium (Ti) alloy surface with periodic microstructure was prepared by a facile laser-based surface texturing approach which combines laser surface texturing and low-temperature annealing. The effect of laser-induced surface texture and wettability on the erosion resistance of the laser textured surface was studied. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to analyze the chemical surface microstructure and surface on the untreated and laser textured surfaces. The hardness and contact angle of the untreated surface, superhydrophilic surface and superhydrophobic surface were measured by microhardness tester and contact angle goniometer. Using an in-house built erosion experimental setup, the erosion resistance of the untreated surface, superhydrophilic surface and superhydrophobic surface was investigated. The experimental results demonstrate that micro-bumps are formed after laser surface texturing. In the meantime, the surface hardness for the laser textured surface with a step size of 150 μm is increased by 48% under the load of 1.961 N. Compared with the untreated surface, the erosion resistance is increased by 33.9%, 23.8% and 16.1%, respectively, for the superhydrophobic surface. The SEM results show that the untreated surface has large and deep impact pits, while the superhydrophobic surface only has small and shallow impact pits, indicating that the erosion process resulted in less damage to the substrate. The EDS results shows that superhydrophobicity plays a critical role in protecting the substrate from erosion. It is thus believed that the superhydrophobic surface has pronounced effects for improving the hardness and erosion resistance of Ti alloy. Full article
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Article
A Study on the Fiber YAG Laser Welding of 304L Stainless Steel
Metals 2021, 11(12), 2022; https://doi.org/10.3390/met11122022 - 14 Dec 2021
Abstract
This work aims to optimize the main YAG fiber laser parameters to weld 304L stainless steel plates of 3 mm thick. Different laser powers (2500, 2000, and 1500 W) and speeds (60, 40, and 20 mm/s) were used and merged in heat input, [...] Read more.
This work aims to optimize the main YAG fiber laser parameters to weld 304L stainless steel plates of 3 mm thick. Different laser powers (2500, 2000, and 1500 W) and speeds (60, 40, and 20 mm/s) were used and merged in heat input, maintaining the defocusing distance at –2 mm to get full penetration. The weld quality and the effect of the laser heat input on the microstructures of the weld and heat-affected zones were investigated. Besides, the fracture strength of the welded joints and hardness distribution through the cross-sections were evaluated. The weld width has a direct relationship with heat input. The laser power of 2800 W produced full penetration joints without any macro defects while reduction in laser power pronounced partial penetration defects. The size of the heat-affected zone in all the processing parameters was very small. The microstructure of the weld zone shows columnar dendrite austenite grains with small arm spacing in most of the welded zone. The size of the dendrites became finer at lower heat input. At a higher heat input, a reasonable amount of lathy equiaxed grains with some delta ferrite occurred. A small amount of delta ferrite was detected in the heat-affected zone, which prevented the crack formation. The hardness of the weld metal was much higher than that of the base metal in all processing parameters and it has a reverse relationship with the heat input. The fracture strength of the welded joints was very close to that of the base metal in the defect-free samples and it increased with decreasing the heat input. Full article
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Article
Effect of High-Speed Powder Feeding on Microstructure and Tribological Properties of Fe-Based Coatings by Laser Cladding
Coatings 2021, 11(12), 1456; https://doi.org/10.3390/coatings11121456 - 26 Nov 2021
Cited by 4
Abstract
In order to improve the wear resistance of 27SiMn steel substrate, Fe-based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high-speed powder feeding (HF) process was used to prepare [...] Read more.
In order to improve the wear resistance of 27SiMn steel substrate, Fe-based alloy coatings were prepared by laser cladding technology in the present study. In comparison to the conventional gravity powder feeding (GF) process, high-speed powder feeding (HF) process was used to prepare Fe-based alloy coating on 27SiMn steel substrate. The effect of diversified energy composition of powder materials on the microstructure and properties of coatings were systematically studied. X-ray diffractometer (XRD), optical microscope (OM) and scanning electron microscope (SEM) were used to analyze the phase structure and microstructure of Fe-based alloy coatings, and the hardness and tribological properties were measured by the microhardness tester and ball on disc wear tester, respectively. The results show that the microstructure of conventional gravity feeding (GF) coatings was composed of coarse columnar crystals. In comparison, owing to the diversification of energy composition, the microstructure of the high-speed powder feeding (HF) coatings consists of uniform and small grains. The total energy of the HF process was 75.5% of that of the GF process, proving that high-efficiency cladding can be achieved at lower laser energy. The refinement of the microstructure is beneficial to improve the hardness and wear resistance of the coating, and the hardness of the HF coating increased by 9.4% and the wear loss decreased to 80.5%, compared with the GF coating. The wear surface of the HF coating suffered less damage, and the wear mechanism was slightly adhesive wear. In contrast, wear was more serious in the GF coating, and the wear mechanism was transformed into severe adhesive wear. Full article
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Article
Laser Surface Alloying of Austenitic 316L Steel with Boron and Some Metallic Elements: Properties
Materials 2021, 14(11), 2987; https://doi.org/10.3390/ma14112987 - 31 May 2021
Cited by 2
Abstract
Austenitic 316L stainless steel is known for its good resistance to corrosion and oxidation. However, under conditions of appreciable mechanical wear, this steel had to demonstrate suitable wear protection. In this study, laser surface alloying with boron and some metallic elements was used [...] Read more.
Austenitic 316L stainless steel is known for its good resistance to corrosion and oxidation. However, under conditions of appreciable mechanical wear, this steel had to demonstrate suitable wear protection. In this study, laser surface alloying with boron and some metallic elements was used in order to improve the hardness and wear behavior of this material. The microstructure was described in the previous paper in detail. The microhardness was measured using Vickers method. The “block-on-ring” technique was used in order to evaluate the wear resistance of laser-alloyed layers, whereas, the potentiodynamic method was applied to evaluate their corrosion behavior. The produced laser-alloyed layers consisted of hard ceramic phases (Fe2B, Cr2B, Ni2B or Ni3B borides) in a soft austenitic matrix. The significant increase in hardness and wear resistance was observed in the case of all the laser-alloyed layers in comparison to the untreated 316L steel. The predominant abrasive wear was accompanied by adhesive and oxidative wear evidenced by shallow grooves, adhesion craters and the presence of oxides. The corrosion resistance of laser-alloyed layers was not considerably diminished. The laser-alloyed layer with boron and nickel was the best in this regard, obtaining nearly the same corrosion behavior as the untreated 316L steel. Full article
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Article
Influence of Microstructure and Chemical Composition on Microhardness and Wear Properties of Laser Borided Monel 400
Materials 2020, 13(24), 5757; https://doi.org/10.3390/ma13245757 - 16 Dec 2020
Cited by 6
Abstract
In this study, wear properties of Monel 400 after laser alloying with boron are described. Surfaces were prepared by covering them with boron paste layers of two different thicknesses (100 µm and 200 μm) and re-melting using diode laser. Laser beam power density [...] Read more.
In this study, wear properties of Monel 400 after laser alloying with boron are described. Surfaces were prepared by covering them with boron paste layers of two different thicknesses (100 µm and 200 μm) and re-melting using diode laser. Laser beam power density was equal to 178.3 kW/cm2. Two laser beam scanning velocities were chosen for the process: 5 m/min and 50 m/min. Surfaces alloyed with boron were investigated in terms of wear resistance, and the surface of untreated Monel 400 was examined for comparison. Wear tests were performed using counterspecimen made from steel 100Cr6 and water as a lubricant. Both quantitative and qualitative analysis of surfaces after wear test are described in this paper. Additionally, microstructures and properties of obtained laser alloyed surfaces are presented. It was found that the wear resistance increased from four to tens of times, depending on parameters of the laser boriding process. The wear mechanism was mainly adhesive for surfaces alloyed with initial boron layer 100 µm thick and evolves to abrasive with increasing boron content and laser beam scanning velocity. Iron particles detached from counterspecimens were detected on each borided surface after the wear test, and it was found that the harder the surface the less built-ups are present. Moreover, adhered iron particles oxidized during the wear test. Full article
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Article
Laser Surface Alloying of Austenitic 316L Steel with Boron and Some Metallic Elements: Microstructure
Materials 2020, 13(21), 4852; https://doi.org/10.3390/ma13214852 - 29 Oct 2020
Cited by 6
Abstract
Austenitic 316L steel is known for its good oxidation resistance and corrosion behavior. However, the poor wear protection is its substantial disadvantage. In this study, laser surface alloying with boron and some metallic elements was used in order to form the surface layers [...] Read more.
Austenitic 316L steel is known for its good oxidation resistance and corrosion behavior. However, the poor wear protection is its substantial disadvantage. In this study, laser surface alloying with boron and some metallic elements was used in order to form the surface layers of improved wear behavior. The microstructure was studied using OM, SEM, XRD, and EDS techniques. The laser-alloyed layers consisted of the only re-melted zone (MZ). The hard ceramic phases (Fe2B, Cr2B, Ni2B, or Ni3B borides) occurred in a soft austenitic matrix. The relatively high overlapping (86%) resulted in a uniform thickness and homogeneous microstructure of the layers. All the laser-alloyed layers were free from defects, such as microcracks or gas pores, due to the use of relatively high dilution ratios (above 0.37). The heat-affected zone (HAZ) wasn’t visible in the microstructure because of the extended stability of austenite up to room temperature and no possibility to change this structure during fast cooling. The use of the mixtures of boron and selected metallic elements as the alloying materials caused the diminished laser beam power in order to obtain the layers of acceptable quality. The thickness of laser-alloyed layers (308–432 μm) was significantly higher than that produced using diffusion boriding techniques. Full article
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