Study on the Impact of the Shielding Gas on the Droplet Transfer Mode and Blowhole Defect of High Nitrogen Steel Welding

doi:10.3901/JME.2017.22.087

Abstract

Abstract: High-nitrogen steel plates with a thickness of 8 mm are welded with a laser-arc composite heat source for experiment to study the impact of different shielding gas compositions on the welding joint profile, droplet transfer features and blowhole defect. The results show that when the pure argon is used as the shielding gas, the droplet transfer mode is mainly shown as spray transfer, accompanied by a small amount of repulsion transfer. When the shielding gas is mixed by Ar+N₂, the droplet transfer mode is short circuiting transfer; when the shielding gas is mixed by Ar+N₂+O₂, the droplet transfer mode is spray transfer. The shielding gas composition has some impact on the blowhole defect of the welding joint. When the shielding gas is pure argon, the blowhole defect rate of the welding joint is at its maximum and its value is 2.52%. When the shielding gas is 90% Ar+10% N₂, the blowhole defect rate is the lowest, only 0.16%; when 1% of the O₂ is added to the mixture of Ar+N₂, the blowhole defect rate slightly rises, but compared with that of pure argon, the blowhole defect rate still drops significantly. When the ternary mixture of Ar+N₂+O₂ is used as the shielding gas, the number of blowholes in the welding joint can be effectively contained, and the droplet transfer mode can be improved to better the stability of the welding process.

Key words: droplet transfer, high nitrogen steels, hybrid welding, shielding gas, welding porosity

CLC Number:

TG456

CUI Bo, ZHANG Hong, LIU Jia, LIU Fengde, ZHANG Fulong. Study on the Impact of the Shielding Gas on the Droplet Transfer Mode and Blowhole Defect of High Nitrogen Steel Welding[J]. Journal of Mechanical Engineering, 2017, 53(22): 87-94.

References

[1] HANS B. Manufacture and application of high nitrogen steels[J]. The Iron and Steel Institute of Japan,1996,36(7):909-914.
[2] 李冬杰,陆善平,李殿中,等. 高氮钢焊缝的组织和冲击性能研究[J]. 金属学报,2013,49(2):129-136. LI Dongjie,LU Shanping,LI Dianzhong,et al. Investigation of the microstructure and impact properties of the high nitrogen stainless steel weld[J]. Acta Metallurgica Sinica,2013,49(2):129-136.
[3] YUJI I,RIKIO N. Effect of thermo-mechanical treatment on mechanical properties of high-nitrogen containing Cr-Mn-Ni austenitic stainless steels[J]. The Iron and Steel Institute of Japan,1996,36(7):855-861.
[4] NAT M. Nitrogen containing austenitic stainless steels[J]. Materialwissenschaft Und Werkstofftechnik,2006,37(10):875-880.
[5] LANG Yuping,QU Huapeng,CHEN Haitao,et al. Research progress and development tendency of nitrogen-alloyed austentic stainless steel[J]. Journal of Iron and Steel Research,2015,22(2):91-98.
[6] STEIN G,HUCKLENBROICH I. Manufacturing and applications of high nitrogen steels[J]. Materials and Manufacturing Processes,2004,19(1):7-17.
[7] HERTZMAN S,WESSMAN S. An experimental and theoretical study of nitrogen flux in stainless steel TIG welds[J]. Materials Science Forum,1999,318-320:579-590.
[8] RAFFI M,MADHUSUDHAN R G,SRINIVASA R K. Microstructure and pitting corrosion of shielded metal arc welded high nitrogen stainless steel[J]. Defence Technology,2015,11(3):237-243.
[9] WOO I,KIKUCHI Y. Weldability of high nitrogen stainless steel[J]. Transactions of JWRI,2002,31(2):129-139.
[10] LI H B,JIANG Z H,FENG H,et al. Microstructure,mechanical and corrosion properties of friction stir welded high nitrogen nickel-free austenitic stainless steel[J]. Materials and Design,2015,84:291-299.
[11] KAMIYA O,CHEN Z W,KIKUCHI Y. Micro-porosity formation in partially melted zone during welding of high nitrogen austenitic stainless steels[J]. Journal of Materials Science,2002,37(12):2475-2481.
[12] GALLOWAY A M,MCPHERSON N A,BAKER T N. An evaluation of weld metal nitrogen retention and properties in 316LN austenitic stainless steel[J]. Proceedings of the Institution of Mechanical Engineers,Part L:Journal of Materials Design and Applications,2011,225(2):61-69.
[13] 赵琳,田志凌,彭云,等. 1Cr22Mn16N高氮钢激光焊接I.焊接保护气体组成和热输入对焊缝氮含量及气孔性的影响[J]. 焊接学报,2007,28(8):89-91,95. ZHAO Lin,TIAN Zhiling,PENG Yun,et al. Laser welding of high nitrogen steel 1Cr22Mn16N Ⅰ. Influence of shielding gas composition and heat input on N₂ content and porosity of weld metal[J]. Transactions of the China Welding Institution,2007,28(8):89-91.
[14] HARZENMOSER M,RENNHARD C,HERETH M,et al. Recent developments on the weldability of a new high nitrogen stainless steel[J]. Materials Science Forum,1999,318(3):591-596.
[15] MIYANO Y,FUJⅡ H,SUN Yufeng,et al. Mechanical properties of friction stir butt welds of high nitrogen-containing austenitic stainless steel[J]. Materials Science and Engineering A,2011,528(6):2917-2921.
[16] 李陈宾,史吉鹏,刘黎明. 低功率脉冲激光-电弧复合热源高效焊接过程中的"匙孔"行为研究[J]. 机械工程学报,2016,52(2):41-46. LI Chenbin,SHI Jipeng,LIU Liming. Study on laser keyhole behavior in high-efficiency low power pulsed laser-TIG hybrid welding process[J]. Journal of Mechanical Engineering,2016,52(2):41-46.
[17] 刘凤德,张宏,杜劭峰,等. 激光功率对CO₂激光-MAG电弧复合焊电弧与熔滴行为的影响[J]. 机械工程学报,2013,49(4):75-82. LIU Fengde,ZHANG Hong,DU Shaofeng,et al. Influence of laser power on arc and droplet behaviors in droplets on CO₂ laser-MAG arc hybrid welding[J]. Journal of Mechanical Engineering,2013,49(4):75-82.
[18] 孙硕,刘双宇,贾冬生,等. 高氮钢激光-电弧复合焊焊缝成形多元非线性回归模型[J]. 机械工程学报,2015,51(8):67-75. SUN Shuo,LIU Shuangyu,JIA Dongsheng,et al. Multiple nonlinear regression model of weld bead shape for high nitrogen steel by laser-arc hybrid welding[J]. Journal of Mechanical Engineering,2015,51(8):67-75.
[19] 王立锋,刘凤德,刘薇娜,等. 高氮钢激光-电弧复合焊接气孔控制方法研究[J]. 机械工程学报,2016,52(20):51-59. WANG Lifeng,LIU Fengde,LIU Weina,et al. Study on control methods of welding porosity in laser-arc hybrid welding for high nitrogen steels[J]. Journal of Mechanical Engineering,2016,52(20):51-59.
[20] LU S P,FUJJI H,NOGI K,et al. Effect of oxygen content in He-O₂ shielding gas on weld shape in ultra-deep penetration TIG[J]. Science and Technology of Welding and Joining,2013,12(8):689-695.
[21] 周业基. 焊接保护气体选择[J]. 广船科技,2000(3):20-24. ZHOU Yeji. The selection of shielding gas[J]. GSI Shipbuilding Technology,2000(3):20-24.
[22] LU S P,FUJJI H,NOGI K. Sensitivity of marangoni convection and weld shape variations to welding parameters in O₂-Ar shielded GTA welding[J]. Scripta Materialia,2004,51(3):271-277.
[23] LU S P,FUJJI H,NOGI K. Marangoni convection and weld shape variations in Ar-O₂ and Ar-CO₂ shielded GTA welding[J]. Materials Science and Engineering A,2004,380(1-2):290-297.
[24] TUSEK J,SUBAN M. Experimental research of the effect of hydrogen in argon as a shielding gas in arc welding of high-alloy stainless steel[J]. Int. J. Hydrogen Energy,2000,25(4):369-376.
[25] HOWARD B C,SCOTT C H. Modern welding technology[M]. New Jersey:Pearson Education,2005.
[26] HERTZMAN S,PARRERSON R J,BLOM R,et al. Influence of shielding gas composition and welding parameters on the N-content and corrosion properties of welds in N-alloyed stainless Steel[J]. ISIJ International,1996,36(7):968-976.