Single-pass keyhole TIG welding (K-TIG) was used to weld 10-mm-thick Invar36 alloy plates without filler metal and groove preparation. The effects of joint gap, welding current, welding speed and arc length on the weld appearance, microstructure and mechanical properties were investigated. No phase transformation occurred in the weld where only austenite (γ-(Fe, Ni)) was formed, while the grain structure changed significantly. The maximum tensile strength of K-TIG weld was 440.7 MPa reaching 99.9% of the base metal and the maximum elongation was 31.5%. The microhardness in the weld zone was slightly lower than that of the base metal. The results suggested that K-TIG welding was a very promising method for the joining of middle-thick Invar36 alloy plates.
ZhaoY, WuAP, YaoW, Microstructure and mechanical properties of Nd: YAG laser welded Invar 36 alloy. Materials Science Forum; 2011: Trans Tech Publ.
2.
ChenY, LiMG, ZhangYH, The development actuality and application prospect of Invar alloy. Mech Res Appl. 2009; 4:9–11.
3.
AbbergerS. L.1997. Advanced Composite Molds—A New Use forInvar, The Invar Effect: A Centennial Symposium, J. Wittenauer,Ed., 7-8 Oct 1996 (Cincinnati, OH), The Minerals, Metals &Materials Society, 1997, p 317–325.
4.
BellwareMD.How to weld Invar. Weld Eng. 1964; 11:41–43.
5.
GottliebT.Fabrication of iron-nickel alloys for cryogenic piping service. Weld J. 1965; 44(3):116–123.
6.
OgawaT.Weldability of Invar and its large-diameter pipe. Weld J. 1986; 65(8):213–226.
7.
CuiSW.Study on the keyhole behavior, microstructure and properties of the welded joints in K-TIG welding [dissertation]. Guangzhou (GD): South China University of Technology; 2019.
8.
ZhanX, LiuX, WeiY, Microstructure and property characteristics of thick Invar alloy plate joints using weave bead welding. J Mater Process Technol. 2017; 244:97–105. doi: 10.1016/j.jmatprotec.2017.01.014
9.
JasthiBK, ArbegastWJ, HowardSM, Thermal expansion coefficient and mechanical properties of friction stir welded Invar (Fe-36%Ni). J Mater Eng Perform. 2009; 18(7):925–934. doi: 10.1007/s11665-008-9320-7
10.
ZhaoY, SatoYS, KokawaH, Microstructure and properties of friction stir welded high strength Fe–36wt% Ni alloy. Mater Sci Eng A. 2011; 528(25–26):7768–7773. doi: 10.1016/j.msea.2011.06.082
LiG, GaoM, ChenC, Characterisation comparison of laser and laser–arc hybrid welding of Invar 36 alloy. Sci Technol Weld Join. 2014; 19(1):30–37. doi: 10.1179/1362171813Y.0000000159
14.
ZhanX, ZhangD, WeiY, Research on the microstructure and properties of laser-MIG hybrid weld of Invar alloy. Opt Laser Technol. 2017; 97:124–136. doi: 10.1016/j.optlastec.2017.06.014
15.
JarvisBL.Keyhole gas tungsten arc welding: a new process variant [dissertation]. Wollongong (NSW): University of Wollongong; 2001.
16.
LathabaiS, JarvisB, BartonKJ, Comparison of keyhole and conventional gas tungsten arc welds in commercially pure titanium. Mater Sci Eng A. 2001; 299(1-2):81–93. doi: 10.1016/S0921-5093(00)01408-8
17.
FengY, LuoZ, LiuZ, Keyhole gas tungsten arc welding of AISI 316L stainless steel. Mater Des. 2015; 85:24–31. doi: 10.1016/j.matdes.2015.07.011
18.
RangZ.Study on Multiphase Coupled Flow Field Behavior during Laser-MIG Hybrid Welding of Invar Alloy [dissertation]. Nanjing (JS): Nanjing University of Aeronautics And Astronautics; 2018.
19.
LiuZ, FangY, QiuJ, Stabilization of weld pool through jet flow argon gas backing in C-Mn steel keyhole TIG welding. J Mater Process Technol. 2017; 250:132–143. doi: 10.1016/j.jmatprotec.2017.07.008
20.
WangH, HuS, ShenJ, Effect of duty cycle on microstructure and mechanical properties of pulsed GTAW lap joint of Invar. J Mater Process Technol. 2017; 243:481–488. doi: 10.1016/j.jmatprotec.2017.01.008
21.
XuG, LiP, LiL, Influence of arc power on keyhole-induced porosity in laser + GMAW hybrid welding of aluminum alloy: Numerical and experimental studies. Materials. 2019; 12(8):1328. doi: 10.3390/ma12081328
22.
ZhanX, GaoQ, GuG, The porosity formation mechanism in the laser-MIG hybrid welded joint of Invar alloy. Opt Laser Technol. 2017; 95:86–93. doi: 10.1016/j.optlastec.2017.04.015
23.
ZhanX, LiuJ, ChenJ, Parameter optimization of multi-pass multi-layer MIG welded joint for invar alloy. Int J Adv Manuf Technol. 2016; 87(1-4):601–613. doi: 10.1007/s00170-016-8544-1
24.
XiaS, LiH, ZhouB, Control and application of annealing twins in metallic materials: grain boundary engineering. Chin J Nat. 2010; 2:94–100.
