李睿 周军 张春波 乌彦全 梁武 秦丰

摘要： 为探索TC4/Ti17异质焊接接头焊接工藝窗口，了解合适的焊接工艺参数，进行了3种不同焊接压力下TC4/Ti17钛合金线性摩擦焊接试验，进行了显微组织及力学性能的对比分析。结果表明，Ti17侧焊缝及热力影响区宽度均大于TC4侧区域，伴随焊接压力的增大下熔合线变得不再清晰;Ti17侧焊缝组织发生了回复与动态再结晶并与TC4侧形成共晶组织，热力影响区及焊缝存在亚稳定β相，TC4侧焊缝组织发生马氏体转变;热力影响区组织受摩擦力作用发生拉长变形和细化。Ti17侧存在2个弱化区且显微硬度较低，一是由于近缝区的亚稳定相β发生转化，二是在焊接热循环下热影响区的二次次生α相发生球化溶解;TC4侧焊缝显微硬度最大，是由于焊缝的β相冷却速度过快发生马氏体转变。当焊接压力为120 MPa时，由于焊接压力不足，拉伸断裂在焊缝，根据断口分析属于脆性断裂;当焊接压力为150 MPa及180 MPa时，焊接压力足够大，拉伸均断在母材，属于韧性断裂。

关键词： 异质钛合金; 线性摩擦焊; 组织分析; 力学性能

中图分类号： TG 453

Abstract： In order to explore the welding process window of TC4/Ti17 heterogeneous welded joint and understand the appropriate welding parameter， linear friction welding tests of TC4/Ti17 titanium alloy under three different welding pressures were carried out， and the microstructure and mechanical properties were compared and analyzed. The results showed that the size of the weld and heat affected zone on Ti17 side was larger than that on TC4 side， and the fusion line became no longer clear with the increase of welding pressure. Microstructure of the weld on Ti17 side underwent recovery and dynamic recrystallization and formed eutectic microstructure with TC4 side. There was metastable β phase in the thermo-mechanical affected zone and weld， and microstructure of the weld on TC4 side underwent martensitic transformation. Microstructure of the thermo-mechanical affected zone was elongated and refined by friction force. There were two weakened zones on Ti17 side with low microhardness， one was due to the transformation of the metastable phase β near weld zone， the other one was due to the spheroidized dissolution of the secondary α phase in heat-affected zone under the welding thermal cycle. The microhardness of TC4 side weld was the largest， which was due to the martensite transformation caused by the rapid cooling rate of β-phase in weld zone. When the welding pressure was insufficient at 120 MPa， the tensile fracture occurred in the weld， which belonged to the brittle fracture according to the fracture analysis. When the welding pressure was large enough at 150 MPa and 180 MPa， the tensile fracture was at the base metal， which belonged to ductile fracture.

Key words：   heterogeneous titanium alloy; linear friction welding; organization analysis; mechanical properties

0 前言

随着时代的发展，航空领域在国内具有着重要地位，航空发动机做为航空飞机关键部件之一，因其满足高推重比、高可靠性、低成本的要求已被广泛应用[1]。面对航空工业的飞速发展，航空发动机零部件的制造方法以及工艺水平也在不断地更新换代。整体叶盘作为航空发动机核心，是将发动机转子其轮盘与叶片加工成一体，与以往的机械连接对比，不仅连接部位尺寸大大减少，减重效果显著;同时也消除了连接部位因装配不当造成的磨损而产生故障[2-3]。……