异质钛合金线性摩擦焊接头微观组织与显微硬度分析

选用优化的工艺参数对TC4/TC17异质钛合金进行线性摩擦焊及测温试验.焊后利用光学显微镜、扫描电镜及显微硬度仪等对接头微观组织及显微硬度进行分析.结果表明,线性摩擦焊接过程中界面温度超过1 200℃、超过β相变温度,在焊后冷却过程中发生再结晶,产生细小针状组织.界面混合区再结晶组织有等轴化甚至球化现象.TC4侧热力影响区由被拉长的α相及破碎的β相组成,TC17侧热力影响区的α相和β相被拉长细化.TC4侧热力影响区组织发生应变强化,TC17侧热力影响区靠近焊缝侧发生一定的软化现象,靠近母材侧强化现象明显.

Investigation on microstructure and microhardness of linear friction welded joints of dissimilar titanium alloys

On the basis of previous welding experiments,the dissimilar titanium alloys TC4/TC17 were welded by linear friction welding and the interface temperature was measured.The joint microstructure and microhardness was analyzed and tested by optical microscope,scanning electronic microscope and microhardness tester,respectively.The results showed that the interface temperature during welding exceeds 1 200 ℃,above β-transformation temperature.Recrystallization happens in the weld zone in the cooling process after welding,which forms a refined needle-like structure.The recrystallized structure of the mixture zone is equiaxed and even spheroidized.In the TMAZ of TC4,the microstructure consists of the elongated α phase and the broken β phase.In the TC17 TMAZ,the α and β phases was elongated and fined.The microhardness results showed that strain-hardening occured in TC4 TMAZ,while TC17 TMAZ was softened near the weld zone and strain-hardening was obvious near the base metal.