热处理对100mm厚TC4钛合金电子束焊接接头性能的影响

针对100mm厚TC4钛合金板进行电子束对接,焊后对接头分别进行850℃再结晶退火和920℃+2 h和500℃+4 h固溶时效热处理,观察接头的微观形貌,测试其硬度和拉伸性能。结果表明,经过再结晶退火后,焊缝中部开始出现β相晶界,热影响区熔合线附近的针状α′相变少,β相等轴晶界开始出现。经过920℃+2 h和500℃+4 h固溶时效处理后,焊缝中部和底部都出现明显的β相晶界,热影响区熔合线附近的β相等轴晶界明显可见,为细片层β转变组织。力学性能测试表明,经过固溶时效热处理的接头焊缝区、热影响区及母材区的显微硬度明显高于焊态,其接头拉伸强度比焊态提升11.3%,屈服强度比焊态提升17.2%,但接头延伸率比焊态降低近59%。

Effect of heat treatment on mechanical properties of welded joint of electron beam welding for TC4 titanium alloy with 100 mm thickness

The welded joints of TC4 titanium alloy plates with thickness of 100 mm are obtained after electron beam welding.The welded joints are divided into three groups.The first group is treated with 850 ℃ recrystallization annealing treatment,the second one is treated with 920 ℃ +2 h and 500 ℃+4 h solid solution and ageing heat treatment and the third one maintains welded state.The microstructure,micro-hardness and tensile properties of different joints are evaluated.The results show that after recrystallization annealing treatment,the β phase boundaries begin to appear in the middle part of the welds,acicular α'phase reduces near the fusion lines in the heat affected zone,and equal axis β phase boundaries begin to appear.After solid solution and ageing heat treatment,the β phase boundaries clearly appeared in the middle and bottom parts of the welds,the equal axis β phase boundary is clearly visible near the fusion lines in the heat affected zone.The mechanics performance testing shows that the micro-hardness of weld zone,heat affected zone and base metal zone of second group joints are all significantly higher than that of the third group joints,the tensile strength of second group joints increases by 11.3％ and its yield strength increases by 17.2％,but its elongation reduces nearly 59％.