Microstructure and mechanical properties of TC4 titanium alloy K-TIG welded joints

TC4钛合金K-TIG焊接接头的显微组织及力学性能

The 12 mm-thick Ti−6Al−4V(TC4)titanium alloy plates were welded using keyhole tungsten inert gas(K-TIG)welding at various heat inputs.The microstructure,grain boundary(GB)characteristics and mechanical properties of the weld metal zone(WMZ)were analyzed.The test results show that the K-TIG welds are well formed,and no obvious defects are observed when the heat input is 2.30−2.62 kJ/mm.When the heat input gradually increases,αlaths increase in length,andα′phase and residualβphase are reduced.The electron backscatter diffraction(EBSD)test results indicate that the high-angle GB proportion in the WMZ increases with the increase of heat input.The tensile strength of the WMZ gradually decreases and the elongation of the WMZ increases when the heat input increases from 2.30 to 2.62 kJ/mm.The impact toughness of the WMZ increases as the heat input increases.

采用锁孔型钨极氩弧焊(K-TIG)在不同热量输入条件下焊接厚度为12 mm的Ti−6Al−4V(TC4)钛合金板,并研究焊缝金属区(WMZ)的显微组织、晶界特征及力学性能。实验结果表明:当输入热量为2.30~2.62 kJ/mm时,K-TIG焊缝成形良好,未出现明显的缺陷;当热输入逐渐增加时,α板条的长度增加,α'相和残余β相减少。电子背散射衍射(EBSD)测试结果表明:WMZ中的大角度晶界比例随着热量输入的增加而增加。当热量输入从2.30增加到2.62 kJ/mm时,WMZ的抗拉强度逐渐降低,伸长率增加。WMZ的冲击韧性随着热量输入的增加而增加。