Special Issue "Welding of Steels"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Mechanical Engineering".

Deadline for manuscript submissions: closed (15 January 2019)

Special Issue Editors

Guest Editor
Prof. Lars-Erik Svensson

Dept of Engineering Science,University West,SE-46186 Trollhättan,Sweden
E-Mail
Interests: material and physical aspects of welding of steels
Guest Editor
Prof. Dr. Leif Karlsson

Dept of Engineering Science, University West, SE-46186 Trollhättan, Sweden
Website | E-Mail
Interests: material and physical aspects of welding of steels

Special Issue Information

Dear Colleagues,

Steels are still an undisputable material for many of constructions made today. Both stainless and ordinary C-Mn steels have developed significantly over the last few years, as a response to new demands for strength, corrosion resistance, etc., for a more sustainable future. However, to make effective use of these steels, they need to be weldable. This Special Issue will deal with welding of modern steels, both newer steels and application of new welding techniques for the lower strength levels as well as new very high strength steels. It will also cover welding of stainless steels, with its multitude of alloys.

Significant research is going on around the world about welding of these new steels, in terms of steel design, consumable design and welding techniques, which need to be highlighted. Papers on experimental investigations as well as numerical analyses are welcome to illustrate the progress made within this field.

Prof. Lars-Erik Svensson
Prof. Dr. Leif Karlsson
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1500 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Welding
  • High strength steels
  • Stainless steels
  • New alloys
  • Metallurgy
  • Welding techniques

Published Papers (9 papers)

View options order results:
result details:
Displaying articles 1-9
Export citation of selected articles as:

Research

Open AccessArticle A New Approach to the Study of Multi-Pass Welds–Microstructure and Properties of Welded 20-mm-Thick Superduplex Stainless Steel
Appl. Sci. 2019, 9(6), 1050; https://doi.org/10.3390/app9061050
Received: 12 February 2019 / Revised: 7 March 2019 / Accepted: 11 March 2019 / Published: 13 March 2019
PDF Full-text (7814 KB) | HTML Full-text | XML Full-text
Abstract
Type 2507 superduplex stainless steel 20 mm in thickness was multi-pass-welded with Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW) processes. Recommended and higher arc energies and inter-pass temperatures were used. Thermal cycles were monitored using a recently developed procedure involving [...] Read more.
Type 2507 superduplex stainless steel 20 mm in thickness was multi-pass-welded with Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW) processes. Recommended and higher arc energies and inter-pass temperatures were used. Thermal cycles were monitored using a recently developed procedure involving the successive instrumentation of the multi-pass welds, pass by pass, by addition of thermocouples in each weld pass. The repeatability of temperature measurements and survival rate of more than 90% of thermocouples confirmed the reliability of the procedure. Reheating by subsequent passes caused a progressive increase in the austenite content of the weld metal. The as-deposited GMAW passes with higher-than-recommended arc energy showed the lowest presence of nitrides. Therefore, the cooling rate—and not the time exposed at the critical temperature range—seems to be the key factor for nitride formation. The welding sequence layout also plays an important role in the distribution of secondary phases. A larger amount and concentration of secondary austenite and σ-phase was found for a larger number of subsequent passes in the immediate vicinity of a specific weld pass. The impact toughness exceeded requirements for all welds. Differences in absorbed energies were related to the amount of micro-inclusions found with the FCAW weld showing the lowest absorbed energies and highest amount of micro-inclusions. Pitting corrosion preferentially initiated in locations with secondary austenite and σ-phase. However, in the absence of these secondary phases, the HAZ containing nitrides was the weakest location where pitting initiated. The results of this work have implications on practical welding for superduplex stainless steels: the current recommendations on maximum arc energy should be revised for large thickness weldments, and the importance of the welding sequence layout on the formation of secondary phases should be considered. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle MAG Welding Tests of Modern High Strength Steels with Minimum Yield Strength of 700 MPa
Appl. Sci. 2019, 9(5), 1031; https://doi.org/10.3390/app9051031
Received: 15 January 2019 / Revised: 4 March 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
PDF Full-text (13806 KB) | HTML Full-text | XML Full-text
Abstract
The modern high strength steel plates have an excellent combination of strength and toughness based on micro-alloying and complex microstructure. Retaining this combination of properties in the weld zone is a major challenge for applications in high-demanding structural construction. This work investigates the [...] Read more.
The modern high strength steel plates have an excellent combination of strength and toughness based on micro-alloying and complex microstructure. Retaining this combination of properties in the weld zone is a major challenge for applications in high-demanding structural construction. This work investigates the weldability of three different modern high strength steel plates, with a thickness of 8 mm. Two of the test materials were produced by a thermo-mechanically controlled process (TMCP) and one by a quenching and tempering method (Q&T). Two-passes MAG (metal active gas) welding was used with four different heat inputs. The tests implemented on all the materials included tensile, hardness profiles (HV5), Charpy-V impact toughness tests, and microstructure analysis using scanning electron microscope (SEM). For one of the TMCP steels, some extended tests were conducted to define how the tensile properties change along the weld line. These tests included tensile tests with digital image correlation (DIC), and 3-point bending tests. The most notable differences in mechanical properties of the welds between the materials were observed in Charpy-V impact toughness tests, mostly at the vicinity of the fusion line, with the Q&T steel more prone to embrittlement of the heat affected zone (HAZ) than the TMCP steels. Microstructural analysis revealed carbide concentration combined with coarse bainitic structures in HAZ of Q&T steel, explaining the more severe embrittlement. During the tensile tests, the DIC measurements have shown a strain localization in the softest region of the HAZ. Increasing the heat input resulted in earlier localization of the strain and less maximum strength. The tensile properties along the weld line were investigated in all welding conditions, and the results emphasize relevant and systematic differences of the yield strength at the transient zones near the start and end of the weld compared with the intermediate stationary domain. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle Correlation of Microstructure and Mechanical Properties of Metal Big Area Additive Manufacturing
Appl. Sci. 2019, 9(4), 787; https://doi.org/10.3390/app9040787
Received: 11 January 2019 / Revised: 14 February 2019 / Accepted: 19 February 2019 / Published: 23 February 2019
PDF Full-text (6148 KB) | HTML Full-text | XML Full-text
Abstract
Metal Big Area Additive Manufacturing (MBAAM) is a novel wire-arc additive manufacturing method that uses a correction-based approach developed at the Oak Ridge National Laboratory (ORNL). This approach is an integrated software method that minimizes the dynamic nature of welding and compensates for [...] Read more.
Metal Big Area Additive Manufacturing (MBAAM) is a novel wire-arc additive manufacturing method that uses a correction-based approach developed at the Oak Ridge National Laboratory (ORNL). This approach is an integrated software method that minimizes the dynamic nature of welding and compensates for build height. The MBAAM process is used to fabricate simple geometry thin walled specimens, using a C-Mn steel weld wire, to investigate the scatter in mechanical properties and correlate them to the underlying microstructure. The uni-axial tensile tests show isotropic tensile and yield properties with respect to building directions, although some scatter in elongation is observed. Large scatter is observed in the Charpy Impact tests. The microstructure characterization reveals mostly homogenous ferrite grains with some pearlite, except for some changes in morphology and grain size at the interface between the build and the base plate. The measured properties and microstructure are compared with the toughness and strength values reported in the literature, and a hypothesis is developed to rationalize the differences. Overall, the MBAAM process creates stable, isotropic, and weld-like mechanical properties in the deposit, while achieving a precise geometry obtained through a real-time feedback sensing, closed loop control system. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle Determination of Residual Welding Stresses in a Steel Bridge Component by Finite Element Modeling of the Incremental Hole-Drilling Method
Appl. Sci. 2019, 9(3), 536; https://doi.org/10.3390/app9030536
Received: 9 January 2019 / Revised: 25 January 2019 / Accepted: 1 February 2019 / Published: 5 February 2019
PDF Full-text (3575 KB) | HTML Full-text | XML Full-text
Abstract
For welded bridge components, the knowledge of residual stresses induced by welding is essential to determine their effect on the fatigue life behavior resulting in optimal fatigue design and a better knowledge about the fatigue strength of these welded connections. The residual stresses [...] Read more.
For welded bridge components, the knowledge of residual stresses induced by welding is essential to determine their effect on the fatigue life behavior resulting in optimal fatigue design and a better knowledge about the fatigue strength of these welded connections. The residual stresses of a welded component in an orthotropic steel bridge deck are determined with the incremental hole-drilling method. This method is specified by the American Society for Testing and Materials ASTM E837-13a and it can be used only when the material behavior is linear-elastic. However in the region of the bored hole, there are relaxed plastic strains present that can lead to significant error of the measured stresses. The hole-drilling procedure is simulated with three-dimensional finite element modeling including a simplistic model of plasticity. The effect of plasticity on uniform in-depth residual stresses is determined and it is concluded that residual stresses obtained under the assumption of linear-elastic material behavior are an overestimation. Including plasticity for non-uniform in-depth residual stress fields results in larger tensile and smaller compressive residual stresses. Larger tensile residual stresses cause premature fatigue failure. Therefore, it is important to take these larger tensile residual stresses into account for the fatigue design of a welded component. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Graphical abstract

Open AccessArticle Stability and Heat Input Controllability of Two Different Modulations for Double-Pulse MIG Welding
Appl. Sci. 2019, 9(1), 127; https://doi.org/10.3390/app9010127
Received: 2 November 2018 / Revised: 20 December 2018 / Accepted: 21 December 2018 / Published: 1 January 2019
PDF Full-text (14852 KB) | HTML Full-text | XML Full-text
Abstract
Aluminum alloy welding frequently experiences difficulties such as heat input control, poor weld formation, and susceptibility to pore generation. We compared the use of two different modulations for double-pulse metal inert gas (MIG) welding to reduce the heat input required to generate oscillations [...] Read more.
Aluminum alloy welding frequently experiences difficulties such as heat input control, poor weld formation, and susceptibility to pore generation. We compared the use of two different modulations for double-pulse metal inert gas (MIG) welding to reduce the heat input required to generate oscillations in the weld pool. The stabilities of rectangular wave-modulated and trapezoidal wave-modulated double-pulse MIG welding (DP-MIG and TP-MIG) were analyzed by examining their welding processes and weld profiles. We found that the transitional pulse in TP-MIG welding results in smoother current transitions, softer welding arc sounds, and a highly uniform fish-scale pattern. Therefore, TP-MIG welding is more stable than DP-MIG welding. The effects of these double-pulse modulation schemes on welding input energy are presented. We propose methods for reducing welding input energy by varying the number of pulses or the pulse base time of low-energy pulse train while keeping the welding current and welding arc stable and unchanged. Compared to DP-MIG welding, TP-MIG welding reduces the input energy by 12% and produces finer grain sizes, which increases weld hardness. Therefore, TP-MIG welding offers a new approach for heat input control in DP-MIG welding of aluminum alloys. The results of this work are significant for aluminum alloy welding. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle Enhancement of Exit Flow Uniformity by Modifying the Shape of a Gas Torch to Obtain a Uniform Temperature Distribution on a Steel Plate during Preheating
Appl. Sci. 2018, 8(11), 2197; https://doi.org/10.3390/app8112197
Received: 14 October 2018 / Revised: 31 October 2018 / Accepted: 6 November 2018 / Published: 9 November 2018
PDF Full-text (12231 KB) | HTML Full-text | XML Full-text
Abstract
The objective of this study is to improve the exit flow uniformity of a gas torch with multiple exit holes for effective heating of a steel plate. The torch was simulated, and combustion experiments were performed for validation. Based on a basic model, [...] Read more.
The objective of this study is to improve the exit flow uniformity of a gas torch with multiple exit holes for effective heating of a steel plate. The torch was simulated, and combustion experiments were performed for validation. Based on a basic model, three different revised models were designed and analyzed with the software ANSYS FLUENT 18.2. The flow uniformity (γ) of the velocity distribution at the multiple exit holes was investigated with the pressure drop ranging from 100 to 500 Pa. The basic model had flow uniformity ranging from 0.849 to 0.852, but the three new models had γ1 = 0.901–0.912, γ2 = 0.902–0.911, and γ3 = 0.901–0.914, respectively. The maximum percentage difference of the flow uniformity index between the three new models and the basic model was 7.3%. The basic model with nonuniform flow distribution made a temperature difference of the back side of the steel plate from the center to the edge of around 229 °C, while the modified model with uniform flow distribution had a smaller temperature difference of 90 °C. The simulation results showed good agreement with our experimental results for both the basic model and the modified model. The modified gas torch made a wider and more uniform temperature distribution on a preheated steel plate than the basic one. The results revealed that a trade-off between cost and flow uniformity, as well as the new gas torch, could be applied to a steel-plate preheating process before welding. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle High-Speed Welding of Stainless Steel with Additional Compensatory Gas Jet Blow Molten Pool
Appl. Sci. 2018, 8(11), 2170; https://doi.org/10.3390/app8112170
Received: 26 September 2018 / Revised: 31 October 2018 / Accepted: 2 November 2018 / Published: 6 November 2018
PDF Full-text (7010 KB) | HTML Full-text | XML Full-text
Abstract
To avoid humping bead defects in high-speed welding, this paper proposes the method of an additional and compensatory gas jet blow molten pool. A pulsed metal inert gas high-speed welding test platform was constructed for compensatory gas jet blow molten pool. A total [...] Read more.
To avoid humping bead defects in high-speed welding, this paper proposes the method of an additional and compensatory gas jet blow molten pool. A pulsed metal inert gas high-speed welding test platform was constructed for compensatory gas jet blow molten pool. A total of 304 stainless steel sheets were used as the welding workpieces under equal heat inputs. Two high-speed butt welding processes were conducted and compared, in which the workpieces were welded with and without compensatory gas jets at 154 cm/min and 167 cm/min, respectively. After high-speed welding with compensatory gas jet blow, the weld appearance was straight, uniform, and high-quality, with no humping bead or undercut defects. The macroscopic morphologies and microstructures of cross-sections of the weld at the toe, near the surface, the middle, and the bottom portion all showed the stirring effect of the gas jet on the molten pool and improved grain refinement degrees. Hardness was enhanced in the weld center and the heat-affected zone. At welding speeds of 154 cm/min and 167 cm/min, the fracture load capacities of the welds were increased by 24.9 and 10.4%, respectively. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle Effect of Additional Shielding Gas on Welding Seam Formation during Twin Wire DP-MIG High-Speed Welding
Appl. Sci. 2018, 8(9), 1658; https://doi.org/10.3390/app8091658
Received: 4 August 2018 / Revised: 3 September 2018 / Accepted: 10 September 2018 / Published: 14 September 2018
PDF Full-text (8222 KB) | HTML Full-text | XML Full-text
Abstract
For diminishing welding defects such as incomplete penetration, which may easily occur during the twin wire Double Pulsed Metal Inert Gas (DP-MIG) high-speed welding, a novel method using additional shielding gas is introduced in this paper. A branch for the additional shielding gas [...] Read more.
For diminishing welding defects such as incomplete penetration, which may easily occur during the twin wire Double Pulsed Metal Inert Gas (DP-MIG) high-speed welding, a novel method using additional shielding gas is introduced in this paper. A branch for the additional shielding gas was specially set near the back end of the protection hood for the DP-MIG nozzle. The constructed gas branch was used for enabling manual intervention in the formation of a high-temperature solid–liquid weld seam just emerging from the nozzle and also for secondary gas protection on the surface of the weld seam. The butt welding test was carried out in the 2205 duplex stainless steel plate and the weld seam was then characterized by a tensile test, metallographic analysis, X-ray non-destructive testing (NDT), hardness analysis, and impact test. The results showed that the introduction of an appropriate amount of additional shielding gas can effectively improve and diminish the unfused weld seam and also improve the mechanical properties such as the tensile properties of the weld joint, the hardness and toughness of the weld joints. Therefore, the introduction of additional shielding gas has further research potential in theory and process practice. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Open AccessArticle Fatigue Strength Assessment of Steel Rollers: On the Reliability of the Strain Energy Density Approach on Real Components
Appl. Sci. 2018, 8(7), 1015; https://doi.org/10.3390/app8071015
Received: 7 June 2018 / Revised: 14 June 2018 / Accepted: 18 June 2018 / Published: 21 June 2018
Cited by 5 | PDF Full-text (1964 KB) | HTML Full-text | XML Full-text
Abstract
Welded joints are one of the most widely applied methods to join different steel components. However, they introduce stress concentrators that are commonly known to reduce the fatigue strength of structures. Several methods have been developed to assess the fatigue behavior of welded [...] Read more.
Welded joints are one of the most widely applied methods to join different steel components. However, they introduce stress concentrators that are commonly known to reduce the fatigue strength of structures. Several methods have been developed to assess the fatigue behavior of welded components, such as the Notch Stress Intensity Factors (NSIFs) approach. However, this approach has been reported to be geometry dependent, and does not allow for a direct comparison of failures occurring at the weld toes with those occurring at the weld roots. This drawback has been overcame by considering the value of the strain energy density (SED) range averaged in a control volume ahead of the notch tip. More than 900 fatigue data of welded joints have been summarized within a single scatter band ΔW-N (strain energy range–umber of cycles to failure) using this approach. The reliability of the just mentioned scatter band in summarizing the fatigue data of real components such as steel welded rollers produced by Rulmeca is herein evaluated. The results prove the reliability of the SED approach to assess the fatigue behavior of welded rollers, paving the way to its diffusion in assessing real components. Full article
(This article belongs to the Special Issue Welding of Steels)
Figures

Figure 1

Appl. Sci. EISSN 2076-3417 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top