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.

中文翻译：

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小孔TIG焊Invar36合金接头的显微组织和力学性能

单道钥匙孔 TIG 焊 (K-TIG) 用于焊接 10 毫米厚的 Invar36 合金板，无需填充金属和坡口制备。研究了接头间隙、焊接电流、焊接速度和弧长对焊缝外观、显微组织和力学性能的影响。仅形成奥氏体（γ-（Fe，Ni））的焊缝未发生相变，而晶粒结构发生显着变化。K-TIG焊缝的最大抗拉强度为440.7 MPa，达到母材的99.9%，最大延伸率为31.5%。焊缝区的显微硬度略低于母材。结果表明，K-TIG 焊接是一种非常有前途的方法，用于连接中厚 Invar36 合金板。