scholarly journals Promoting austenite formation in laser welding of duplex stainless steel—impact of shielding gas and laser reheating

2020 ◽  
Author(s):  
Amir Baghdadchi ◽  
Vahid A. Hosseini ◽  
Kjell Hurtig ◽  
Leif Karlsson
Keyword(s):  
Laser Welding ◽  
Equilibrium Phase ◽  
Austenite Formation ◽  
Shielding Gas ◽  
Pure Nitrogen ◽  
Austenite Fraction ◽  
Weld Metals ◽  
Nitride Formation ◽  
Laser Welds ◽  
Evolution Of Microstructure

Abstract Avoiding low austenite fractions and nitride formation are major challenges in laser welding of duplex stainless steels (DSS). The present research aims at investigating efficient means of promoting austenite formation during autogenous laser welding of DSS without sacrificing productivity. In this study, effects of shielding gas and laser reheating were investigated in welding of 1.5-mm-thick FDX 27 (UNS S82031) DSS. Four conditions were investigated: Ar-shielded welding, N2-shielded welding, Ar-shielded welding followed by Ar-shielded laser reheating, and N2-shielded welding followed by N2-shielded laser reheating. Optical microscopy, thermodynamic calculations, and Gleeble heat treatment were performed to study the evolution of microstructure and chemical composition. The austenite fraction was 22% for Ar-shielded and 39% for N2-shielded as-welded conditions. Interestingly, laser reheating did not significantly affect the austenite fraction for Ar shielding, while the austenite fraction increased to 57% for N2-shielding. The amount of nitrides was lower in N2-shielded samples compared to in Ar-shielded samples. The same trends were also observed in the heat-affected zone. The nitrogen content of weld metals, evaluated from calculated equilibrium phase diagrams and austenite fractions after Gleeble equilibrating heat treatments at 1100 °C, was 0.16% for N2-shielded and 0.11% for Ar-shielded welds, confirming the importance of nitrogen for promoting the austenite formation during welding and especially reheating. Finally, it is recommended that combining welding with pure nitrogen as shielding gas and a laser reheating pass can significantly improve austenite formation and reduce nitride formation in DSS laser welds.

Effect of shielding gas on the plasma plume in pulsed laser welding

Measurement ◽  
2019 ◽  
Vol 134 ◽  
pp. 25-32 ◽  
Author(s):  
Jie Xu ◽  
Yi Luo ◽  
Liang Zhu ◽  
Jingtao Han ◽  
Chengyang Zhang ◽  
...  
Keyword(s):  
Laser Welding ◽  
Plasma Plume ◽  
Pulsed Laser ◽  
Shielding Gas ◽  
Pulsed Laser Welding

Influence of CO2-Ar Mixtures as Shielding Gas on Laser Welding of Al-Mg Alloys

2013 ◽  
Vol 44 (13) ◽  
pp. 5711-5723 ◽  
Author(s):  
Zouhair Boukha ◽  
José María Sánchez-Amaya ◽  
Leandro González-Rovira ◽  
Eloy Del Rio ◽  
Ginesa Blanco ◽  
...  
Keyword(s):  
Laser Welding ◽  
Mg Alloys ◽  
Shielding Gas ◽  
Al Mg Alloys

Effect of Shielding Gas on Joint Morphology and Mechanical Property of Fiber Laser Welding of A304 Thin Sheet

2017 ◽  
Vol 54 (1) ◽  
pp. 011404
Author(s):  
樊 宇 Fan Yu ◽  
李沛智 Li Peizhi ◽  
柳岸敏 Liu Anmin ◽  
陈 正 Chen Zheng ◽  
郭 跃 Guo Yue
Keyword(s):  
Mechanical Property ◽  
Laser Welding ◽  
Fiber Laser ◽  
Thin Sheet ◽  
Shielding Gas ◽  
Fiber Laser Welding ◽  
Joint Morphology

scholarly journals Formation of Chromium Nitride and Intragranular Austenite in a Super Duplex Stainless Steel

2019 ◽  
Vol 50 (12) ◽  
pp. 5594-5601 ◽  
Author(s):  
N. Holländer Pettersson ◽  
D. Lindell ◽  
F. Lindberg ◽  
A. Borgenstam
Keyword(s):  
Heat Treatment ◽  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Chromium Nitride ◽  
Electron Diffraction Data ◽  
Austenite Formation ◽  
Super Duplex Stainless Steel ◽  
Chromium Nitrides ◽  
Nitride Formation ◽  
Secondary Austenite

Abstract Precipitation of chromium nitrides and formation of intragranular austenite were studied in detail for the super duplex stainless steel grade 2507 (UNS S32750). The situation of multipass welding was simulated by heat treatment at 1623 K (1350 °C) and quenching followed by short heat treatments at 1173 K (900 °C). The microstructural evolution was characterized using transmission and scanning electron microscopy, electron backscatter, and transmission Kikuchi diffraction, and it was observed that the interior of the ferrite grains contained chromium nitrides after quenching. The nitrides were predominantly of CrN with a cubic halite-type structure and clusters of CrN-Cr2N where rod-shaped trigonal Cr2N particles had nucleated on plates of CrN. After heat treatment for 10 seconds at 1173 K (900 °C), the nitride morphology was transformed into predominantly rod-shaped Cr2N, and finely dispersed intragranular secondary austenite idiomorphs had formed in the nitride-containing areas within the ferrite grains. After 60 seconds of heat treatment, both the Cr2N nitrides and the secondary austenite were coarsened. Analysis of electron diffraction data revealed an inherited crystallographic relationship between the metastable CrN and the intragranular austenite. The mechanism of chromium nitride formation and its relation to secondary austenite formation in duplex stainless steels are discussed.

Laser Welding in Vortex Flow Shielding Gas with Tornado Nozzle. Numerical Analysis of Swirling Motion on Welding Results.

2001 ◽  
Vol 19 (1) ◽  
pp. 37-43 ◽  
Author(s):  
Shinichiro YOKOYA ◽  
Shigeta TAKAGI ◽  
Tomonori OGATA ◽  
Seiji KATAYAMA ◽  
Akira MATUNAWA
Keyword(s):  
Numerical Analysis ◽  
Laser Welding ◽  
Vortex Flow ◽  
Shielding Gas

Influence of thermal deformation and shielding gas on topography of weld in deep-penetration laser welding

1996 ◽  
Author(s):  
Hongliang Qiang ◽  
Zhaogu Cheng ◽  
Jiangtao Luo ◽  
Gang Chen ◽  
Runwen Wang
Keyword(s):  
Laser Welding ◽  
Thermal Deformation ◽  
Deep Penetration ◽  
Shielding Gas

scholarly journals Influence of Beam Speed on Residual Stresses in the Vicinity of Laser Welds

2014 ◽  
Vol 996 ◽  
pp. 463-468
Author(s):  
Nikolaj Ganev ◽  
Kamil Kolařík ◽  
Zdenek Pala ◽  
Stanislav Němeček ◽  
Jiří Čapek
Keyword(s):  
Residual Stresses ◽  
Laser Beam ◽  
Laser Welding ◽  
Grain Sizes ◽  
Laser Welds ◽  
Contribution Mapping ◽  
Compressive Residual Stresses

One of the drawbacks of the laser welding is distortion of the welded bodies that is closely linked with the generation and redistribution of residual stresses in the vicinity of the weld. In this contribution, mapping of surface macroscopic residual stresses and grain sizes was performed for several welds created with the laser beam with various speeds. Larger distortions are exhibited by samples manufactured with higher laser beam speed, which also exhibit substantial compressive residual stresses perpendicularly to the welds axis.

Effect of Shielding Gas Mixture on Gas Metal Arc Welding (GMAW) of Low Carbon Steel (LR Grade A)

2016 ◽  
Vol 705 ◽  
pp. 250-254 ◽  
Author(s):  
Yustiasih Purwaningrum ◽  
Triyono ◽  
M. Wirawan Pu ◽  
Fandi Alfarizi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Carbon Steel ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Low Carbon Steel ◽  
Low Carbon ◽  
Shielding Gas ◽  
Weld Metals ◽  
Metal Arc Welding

The aimed of this research is to determine the feasibility and effect of the mixture of the shielding gas in the physical and mechanical properties. Low carbon steel LR grade A in a thickness 12 mm were joined in butt joint types using GMAW (Gas Metal Arc Welding) with groove’s gap 5 mm and groove angle’s 400 with variation of shielding gas composition. The composition of shielding gas that used were 100% Ar, 100 % CO2 and 50% Ar + 50 % CO2. The measured of mechanical properties with regard to strength, hardness and toughness using, tensile test, bending test, Vickers hardness Test, and Charpy impact test respectively. The physical properties examined with optical microscope. Results show that tensile strength of welding metals are higher than raw materials. Welds metal with mixing Ar + CO shielding gas has the highest tensile strength. Hardness of weld metals with the shielding gas 100% Ar, 100 % CO2 and 50% Ar + 50 % CO2 are 244.9; 209.4; and 209.4 VHN respectively. The temperature of Charpy test was varied to find the transition temperature of the materials. The temperature that used were –60°C, -40°C, -20°C, 0°C, 20°C , and room temperature. Weld metals with various shielding gas have similar trends of toughness flux that was corellated with the microstructure of weld .

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