Search Results (141)

Machining chromium–nickel alloy steel is challenging due to its material properties, such as high strength and toughness. These properties often lead to tool damage and degradation of tool life, which overall impacts the production time, cost, and quality of the product. Therefore, it is essential to investigate early signs of tool damage to determine the effective machining conditions for chromium–nickel alloy steel, thereby increasing tool life and improving product quality. In this study, the early signs of tool wear were observed in a physical vapor deposition (PVD) carbide-coated tool (Seco Tools, Björnbacksvägen, Sweden) during the machining of X5CrNi18-10 steel under both dry and wet conditions. A finish turning operation was performed on the outer diameter (OD) of the workpiece with a 0.4 mm nose radius tool. At the early stage, the tool was examined from the functional side (f–side) and the passive side (p–side). The results indicate that dry machining leads to increased coating removal, more heat generation, and visible damage, such as pits and surface scratches. By comparison, wet machining helps reduce heat and wear, thereby improving tool life and machining quality. These findings suggest that a coolant must be used when machining chromium–nickel alloy steel with a PVD carbide-coated tool. Full article

This study investigates the mechanical, tribological, and electrochemical behaviour of a novel precipitation-hardenable martensitic alloy produced by selective laser melting (SLM). The alloy was specifically engineered with an optimised composition, free from cobalt and molybdenum, and featuring reduced nickel content (7 wt.%) and 8 wt.% chromium. It has been developed as a cost-effective and sustainable alternative to conventional maraging steels, while maintaining high mechanical strength and a refined microstructure tailored to the steep thermal gradients inherent to the SLM process. Several ageing heat treatments were assessed to evaluate their influence on microstructure, hardness, tensile strength, retained austenite content, dislocation density, as well as wear behaviour (pin-on-disc test) and corrosion resistance (polarisation curves in 3.5%NaCl). The results indicate that ageing at 540 °C for 2 h offers an optimal combination of hardness (550–560 HV), tensile strength (~1700 MPa), microstructural stability, and wear resistance, with a 90% improvement compared to the as-built condition. In contrast, ageing at 600 °C for 1 h enhances ductility and corrosion resistance (Rp = 462.2 kΩ; Ecorr = –111.8 mV), at the expense of a higher fraction of reverted austenite (~34%) and reduced hardness (450 HV). This study demonstrates that the mechanical, surface, and electrochemical performance of this novel SLM-produced alloy can be effectively tailored through controlled thermal treatments, offering promising opportunities for demanding applications requiring a customised balance of strength, durability, and corrosion behaviour. Full article

This study examines the corrosion characteristics of GRX-810, a NiCoCr-based high entropy alloy, in a simulated marine environment represented by 3.5 wt.% NaCl solution. The research employs electrochemical and surface analysis techniques to evaluate the corrosion performance and protective mechanisms of this alloy. Electrochemical characterization was performed using potentiodynamic polarization to determine critical corrosion parameters, including corrosion potential and current density, along with electrochemical impedance spectroscopy to assess the stability and protective qualities of the oxide film. Surface analytical techniques provided detailed microstructural and compositional insights, with scanning electron microscopy revealing the morphology of corrosion products, energy-dispersive X-ray spectroscopy identifying elemental distribution in the passive layer, and X-ray diffraction confirming the chemical composition and crystalline structure of surface oxide. The results demonstrated distinct corrosion resistance behavior between the different processing conditions of the alloy. The laser powder bed fused (LPBF) specimens in the as-built condition exhibited superior corrosion resistance compared to their hot isostatically pressed (HIPed) counterparts, as evidenced by higher corrosion potentials and lower current densities. Microscopic examination revealed the formation of a dense, continuous layer of corrosion products on the alloy surface, indicating effective barrier protection against chloride ion penetration. A compositional analysis of all samples identified oxide film enriched with chromium, nickel, cobalt, aluminum, titanium, and silicon. XRD characterization confirmed the presence of chromium oxide (Cr₂O₃) as the primary protective phase, with additional oxides contributing to the stability of the film. This oxide mixture demonstrated the alloy’s ability to maintain passivity and effective repassivation following film breakdown. Full article

This article discusses the development of a technology for producing nickel- and chromium-containing ferroalloy through the carbothermic reduction of low-grade ores from the Batamsha deposit. Thermodynamic modeling of phase formation was carried out using the Chemistry 10 software package, along with a series of pilot-scale smelting experiments in a submerged arc furnace. The influence of technological parameters, particularly slag basicity, on the distribution of nickel and chromium in the alloy was studied. The results of an X-ray phase analysis confirmed the modeling conclusions, revealing the presence of nickel and chromium silicide phases. The proposed technology demonstrated a high metal recovery rate and process stability, indicating its potential for industrial application in Kazakhstan. Full article

The present study aims to investigate the microstructural evolution and local mechanical properties of an AlFe18Si8Cr5Ni2 alloy processed via Powder Bed Fusion–Laser-Based Manufacturing (PBF-LB/M). Designed with a focus on sustainability, this alloy was produced by deriving the necessary elements from AlSi10Mg and 304L steel, two of the most widely used alloys and, consequently, among the easiest materials to source from machining scrap. By leveraging iron, chromium, and nickel from these widespread standard compositions, the alloy mitigates the detrimental effects of Fe contamination in Al-based alloys while simultaneously enhancing mechanical performance. A comprehensive investigation of the impact of rapid solidification and thermal cycling offered novel insights into phase stability, elemental distribution, and local mechanical behavior. In particular, microstructural analyses using scanning electron microscopy (SEM), field emission SEM, energy-dispersive X-ray spectroscopy, X-ray diffraction, and differential scanning calorimetry revealed significant phase modifications post PBF-LB/M processing, including Fe-rich acicular phase segregation at melt pool boundaries and enhanced strengthening phase formation. In addition, nanoindentation mapping was used to demonstrate the correlation between microstructural heterogeneity and local mechanical properties. The findings contribute to a deeper understanding of Al-Fe-Si-Cr-Ni alloy changes after the interaction with the laser, supporting the development of high-performance, sustainable Al-based materials for PBF-LB/M applications. Full article

This study investigates the tribocorrosion behavior of 304 stainless steel (304SS), S31254 super austenitic stainless steel (S31254 SASS), and a medium-entropy austenitic stainless steel (MEASS) in 3.5 wt.% NaCl solution under sliding conditions. The objective is to clarify the performance differences among these alloys when exposed to simultaneous mechanical wear and corrosion. Electrochemical techniques, including potentiodynamic polarization and potentiostatic sliding tests, were used to evaluate corrosion resistance and repassivation behavior. Quantitative analysis based on ASTM G119 revealed that MEASS showed a 68% lower total material loss compared to 304SS and a 55% lower loss compared to S31254. MEASS also exhibited the lowest corrosion current density (1.46 μA/cm²) under tribocorrosion conditions, representing an 83% reduction compared to 304SS. These improvements are attributed to the higher chromium and nickel contents of MEASS, which enhance passive film stability and reduce susceptibility to localized corrosion. The results demonstrate that MEASS offers superior resistance to combined mechanical and corrosive degradation in chloride-containing environments. Full article

The short-term mechanical properties of commercial corrosion-resistant nickel alloys based on Ni-Cr (Hastelloy^® G-35^® or UNS N06035), Ni-Mo (Hastelloy^® B-3^® or UNS N10675), and Ni-Cr-Mo (VDM^® Alloy C-4 or UNS N06455, VDM^® Alloy 59 or UNS N06059, and KhN62M-VI) systems were analyzed in the as-received state and after long-term (up to 5000 h) aging at 500–700 °C. All alloys exhibited moderate strength and high ductility in the as-received state. Under the influence of high temperatures, these alloys showed a tendency toward the decomposition of Ni-based FCC solid solutions and a change in mechanical properties. It was shown that the difference in chromium and molybdenum content in Ni-Cr-Mo alloys leads to the formation of secondary phases of various composition and morphology, which had varied influence on the short-term mechanical properties of the materials. Grain boundary precipitates had a negligible effect on the strength properties of the investigated alloys, while intragranular precipitates embrittled nickel-based alloys, reducing their possible application at high temperatures. Full article

Objective: This study aims to evaluate cell proliferation capacity and micronuclei incidence in the presence of nickel–chromium (Ni-Cr)-based dental alloys, with and without the addition of beryllium (Be). The use of these alloys in dental prosthetics is widespread; however, the potential risks associated with their genotoxicity and cytotoxicity require further investigation. The study seeks to provide insight into the safety of these materials and their long-term impact on the health of both patients and dental professionals. Methods: The study was conducted through a comparative analysis of genotoxicity and cytotoxicity using human lymphocyte cultures exposed to two types of Ni-Cr-based dental alloys, one containing beryllium and the other without beryllium. The evaluations were performed according to the OECD Test No. 487 guideline, employing the micronucleus assay and cell proliferation assay. Lymphocytes were exposed to three different alloy concentrations (5 mg/mL, 10 mg/mL, and 20 mg/mL), and the effects on genetic material were analyzed microscopically. Descriptive statistics (mean, standard deviation, and variance) were calculated, and one-way ANOVA was used to assess statistical significance between groups, with a significance threshold of p < 0.05. Results: A significant increase in cytotoxicity and micronuclei incidence was observed in the samples containing beryllium compared to those without beryllium. Statistical analysis revealed significant differences (p < 0.001) between the test and control groups and between different concentrations. Additionally, a direct proportional relationship was noted between alloy concentration and the intensity of genotoxic effects. Microscopic analysis confirmed genetic material damage, indicating a potentially increased risk associated with the use of this type of dental material. Conclusions: The data obtained suggest that Ni-Cr-based dental alloys containing beryllium may present a significant risk of genotoxicity and cytotoxicity. Therefore, the selection of materials used in dental prosthetics should be based on solid scientific evidence, and the use of these alloys should be approached with caution. The study highlights the need for further research to better understand the long-term impact of these materials on human health. Full article

Passive films that form on Alloy 600 and Alloy 690 during four hours in simulated Primary Water (PW) of Pressurized Water Nuclear Reactors (PWRs) at 320 °C were investigated by in situ surface-enhanced Raman spectroscopy (SERS). Similar tests conducted on unalloyed nickel, unalloyed chromium, and laboratory alloys of Ni-10Cr, Ni-20Cr, Ni-5Cr-8Fe, and Ni-10Cr-8Fe aided in assigning the peaks in the surface-enhanced Raman (SER) spectra of the passive films of Alloy 600 and Alloy 690. SERS indicates an inner layer (IL) of Cr₂O₃/CrOOH forms on both Alloy 600 and Alloy 690 and that Alloy 690’s IL was more protective against corrosion due to its greater resistance to ion transport. The outer layer (OL) of Alloy 600 consists of NiO and spinels, FeCr₂O₄—M(Cr,Fe)₂O₄. The OL of Alloy 690 contains no spinel. A comparison of SER spectra in 320 °C PWR PW to the spectra following cooling down to room temperature and after exposure to air indicates some differences between in situ films and ex situ films. Full article

This article presents the results of laboratory studies on the smelting of nickel–chromium-containing ferroalloys from low-grade nickel ores from Kazakhstan. X-ray phase analysis was performed on raw materials, which included quartz, nontronite, chromium metahydroxide, goethite, magnetite, iron chromite, and nickel (II) silicate. The reduction reactions of metal oxides with carbon and carbon monoxide were studied as the temperature increased. Experimental smelting was carried out in a Tammann furnace at 1500–1550 °C using three types of reducing agent: RK coke, as well as its mixtures with low-ash Shubarkol coal, in ratios of 75:25 and 50:50. The second option demonstrated the highest economic efficiency, achieving a 91% nickel recovery rate, reduced coke consumption, and a slag-to-metal ratio of 3.07. Chemical analysis showed that the nickel content in the obtained alloys ranged from 2.5% to 6.5%, while chromium content ranged from 2.6% to 4.5%. X-ray phase analysis confirmed the presence of Fe₂Ni_0.6Si, Fe₅Si₃, and Fe₂CrSi phases in the alloy structure. Local element concentrations varied within the following ranges: Fe—55–59%, Ni—2–10%, Cr—2–7%, and Si—29–35%. The results of this study confirmed the feasibility of producing a nickel–chromium-containing alloy with a nickel content of 2–10% and a chromium content of 2–7%. Full article

Copper–nickel alloys are widely applied in marine engineering due to their excellent mechanical properties and corrosion resistance. This study investigates the effect of chromium (Cr) on the erosion–corrosion behavior of copper–nickel alloys through erosion–corrosion experiments. The results indicate that the alloy containing Cr exhibits enhanced erosion–corrosion resistance. The addition of Cr reduces the corrosion rate of the copper–nickel alloy from 0.206 mm/a to 0.060 mm/a. This improvement in corrosion resistance is mainly attributed to the formation of (Ni/Fe)₃Cr phases, which enhance the alloy’s strength and further improve its erosion resistance. Furthermore, Cr increases the electrochemical resistance of the corrosion products. Full article

This study presents the results of laboratory experiments on the processing of lateritic nickel ores mixed with coal and CaO, followed by the use of the obtained product for the smelting of nickel-containing ferroalloy by the metallothermic method. The study analyzed the thermodynamic effects of complex reductant concentration (silicon- and aluminum-containing alloy) on the reduction degree of nickel and iron. An experimental process resulted in a product containing Ni_total (2.60%) and Fe_total (60.52%), obtained through reduction roasting of lateritic nickel ore mixed with coal and an addition of 20 g of CaO at a temperature of 1150 °C. Under laboratory conditions, a nickel-containing ferroalloy was successfully obtained using the product after reduction roasting and a complex alloy as the reducing agent. The following optimal process parameters were determined: reductant consumption of 20 g per 100 g of the reduction roasting product, smelting temperature of 1600 °C, and slag basicity (CaO/SiO₂) of 0.5. In this case, a nickel-containing ferroalloy with 72% iron, 15% nickel, and up to 5% chromium was successfully obtained through silicon and aluminum reduction using a complex alloy. A microstructural analysis of the nickel-containing alloy was conducted using an electron probe microanalyzer (JXA-8230) in combination with scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that silicon and iron were the dominant elements in all particles. Nickel was detected at concentrations of up to 15.02 wt. %, while chromium reached 3.47 wt. %. Depending on the silicon concentration, the nickel-containing ferroalloy is recommended for corrosion-resistant steel production (Si < 5%) and as a reducing agent for ferronickel production (Si > 5%). Full article

Hip joint implants are among the most prevalent types of medical implants utilized for the replacement of damaged joints. The utilization of modern implant materials, such as cobalt–chromium alloys, stainless steel, titanium, and other titanium alloys, is accompanied by challenges, including the toxicity of certain elements (e.g., aluminum, vanadium, nickel) and excessive Young’s modulus, which adversely impact biomechanical compatibility. A mismatch between the stiffness of the implant material and the bone tissue, known as stress shielding, can lead to adverse outcomes such as bone resorption and implant loosening. Recent studies have shifted the focus to β-titanium alloys due to their exceptional biocompatibility, corrosion resistance, and low Young’s modulus, which is close to the Young’s modulus of bone tissue (10–30 GPa). In this study, the microstructure, mechanical properties, and phase stability of the Ti-38Zr-11Nb alloy were investigated. Energy dispersion spectrometry was employed to confirm the homogeneous distribution of Ti, Zr, and Nb in the alloy. A subsequent microstructural analysis revealed the presence of elongated β-grains subsequent to rolling and quenching. Furthermore, grinding contributed to the process of recrystallization and the formation of subgrains. X-ray diffraction analysis confirmed the presence of a stable β-phase under any heat treatment conditions, which can be explained by the use of Nb as a β-stabilizer and Zr as a neutral element with a weak β-stabilizing effect in the presence of other β-stabilizers. Furthermore, the modulus of elasticity, as determined by tensile testing, exhibited a decline from 85 GPa to 81 GPa after annealing. Mechanical tests demonstrated a substantial enhancement in tensile strength (from 529 MPa to 628 MPa) concurrent with a 32% reduction in elongation to fracture of the samples. These alterations are attributed to microstructural transformations, including the formation of subgrains and the rearrangement of dislocations. This study’s findings suggest that the Ti-38Zr-11Nb alloy has potential as a material of choice due to its lower Young’s modulus compared to traditional materials and its stable β-phase, which enhances the implant’s durability and reduces the risk of brittle phases forming over time. This study demonstrates that the corrosion resistance of titanium grade 2 and Ti-38Zr-11Nb is comparable. The material in question exhibited no evidence of cytotoxic activity in the context of mammalian cells. Full article

The widespread adoption of metal implants in orthopaedics and dentistry has revolutionized medical treatments, but concerns remain regarding their biocompatibility, toxicity, and immunogenicity. This study conducts a comprehensive literature review of traditional biomaterials used in orthopaedic surgery and traumatology, with a particular focus on their historical development and biological interactions. Research articles were gathered from PubMed and Web of Science databases using keyword combinations such as “toxicity, irritation, allergy, biomaterials, corrosion, implants, orthopaedic surgery, biocompatible materials, steel, alloys, material properties, applications, implantology, and surface modification”. An initial pool of 400 articles was screened by independent reviewers based on predefined inclusion and exclusion criteria, resulting in 160 relevant articles covering research from 1950 to 2025. This paper explores the electrochemical processes of metals like iron, titanium, aluminium, cobalt, molybdenum, nickel, and chromium post-implantation, which cause ion release and wear debris formation. These metal ions interact with biological molecules, triggering localized irritation, inflammatory responses, and immune-mediated hypersensitivity. Unlike existing reviews, this paper highlights how metal–protein interactions can form antigenic complexes, contributing to delayed hypersensitivity and complications such as peri-implant osteolysis and implant failure. While titanium is traditionally considered bioinert, emerging evidence suggests that under certain conditions, even inert metals can induce adverse biological effects. Furthermore, this review emphasizes the role of oxidative stress, illustrating how metal ion release and systemic toxicity contribute to long-term health risks. It also uncovers the underappreciated genotoxic and cytotoxic effects of metal ions on cellular metabolism, shedding light on potential long-term repercussions. By integrating a rigorous methodological approach with an in-depth exploration of metal-induced biological responses, this paper offers a more nuanced perspective on the complex interplay between metal implants and human biology, advancing the discourse on implant safety and material innovation. Full article

High chromium cast iron (HCCI) is widely used in the manufacturing of equipment parts in the fields of mining, cement, electric power, metallurgy, the chemical industry, and paper-making because of its excellent wear and corrosion resistance. Although the microstructure and properties of HCCI can be modified by controlling the casting and heat treatment process, alloying is still the most basic and important method to improve the properties of HCCI. There are about 14 common alloying elements in HCCI, among which nickel, copper, and manganese are typical austenite stabilizing elements, which can increase austenite content and matrix electrode potential. The addition of elements such as silicon, nitrogen, boron, and rare earth (RE) is often small, but it has a significant effect on tailoring the microstructure, thereby improving wear resistance and impact toughness. It was thought that after years of development, the research on the role of the above elements in HCCI was relatively complete, but in the past 5 to 10 years, there has been a lot of new research progress. Moreover, the current development situation of HCCI is still relatively extensive, and there are still many problems regarding the alloying of HCCI to be further studied and solved. In this paper, the research results of austenitic stabilizing elements and modifying elements in HCCI are reviewed. The existing forms, distribution law of these elements in HCCI, and their effects on the microstructure, hardness, wear resistance, and corrosion resistance of HCCI are summarized. Combined with the current research situation, the future research and development direction of HCCI alloying is prospected. Full article