异质钛合金线性摩擦焊接头形成过程及组织特征

Investigation on joint establishment and weld microstructure during linear friction welding of dissimilar titanium alloys

关键词:  线性摩擦焊  钛合金  组织  界面温度

Key words:  linear friction welding  titanium alloy  microstructure  interface temperature

摘要:

对TC4和TC17异质钛合金线性摩擦焊接头形成及接头组织特征进行分析,并测量了动态平衡阶段的界面温度.结果表明,在摩擦初期界面容易产生大的磨损颗粒,摩擦过渡阶段两侧基体材料产生大的塑性变形,大的磨损颗粒被细化,摩擦界面开始产生高温粘塑性金属;动态平衡摩擦阶段高温粘塑性金属被均匀的挤出界面形成飞边,焊后界面两侧组织被细化.测温结果显示,摩擦过程中界面温度超过1 200℃,高于两基体材料的相变温度,TC17侧焊缝中形成再结晶β晶粒,TC4侧形成典型的魏氏组织,焊缝两侧的热力影响区产生明显的变形,组织均被拉长.

Abstract:

Linear friction welding of TC4 to TC17 titanium alloys was conducted,and the joint establishment and weld microstructure was analyzed. The interface temperature in the dynamic equilibrium phase was measured. The results show that large wear particles were easily generated in the interface in the initial phase. During the transition phase,the large wear particles were expelled from the rubbing interface and high temperature plasticized layer formed. Then the viscoplastic metal homogeneously moved out of the rubbing interface and formed a flash, and the grains on both sides of the interface were refined. It was observed that the temperature during the dynamic equilibrium phase exceeded 1 200℃,higher than the phase transition temperatures of both base materials,which led to the generation of recrystallized β grain,and then widmanstatten structure by α-β transformation. The microstructure in the thermal-mechanically affected zone (TMAZ) was apparently deformed and elongated.