TC4钛合金厚板窄间隙TIG焊接接头的高周疲劳性能

High cycle fatigue properties of narrow gap TIG welded joint of thick TC4 titanium alloy plate

为了确定厚板TC4钛合金窄间隙TIG焊接接头的疲劳性能,对焊接接头三层位置的样品分别进行了室温高周疲劳(HCF)试验,利用扫描电镜与透射电镜对疲劳断口形貌及断口附近的微观组织进行观察与分析.结果表明:三层焊接接头的疲劳极限依次为420、390和400 MPa;第一层焊接接头的疲劳裂纹萌生于样品表面,位错组态以位错网络和位错阵列为主;第二层焊接接头的疲劳裂纹萌生于样品表面与焊接缺陷处,位错组态主要为位错缠结;第三层焊接接头的疲劳裂纹萌生于样品表面与近表面焊接气孔位置,位错组态主要为位错阵列及位错缠结.

In order to determine the fatigue properties of narrow gap TIG welded joint of thick TC4 titanium alloy plate,the high cycle fatigue(HCF)tests at room temperature were carried out with the samples at three layers of welded joint,respectively.The morphologies of fatigue fracture surfaces and the microstructures near the fracture surface were observed and analyzed with scanning electron microscope and transmission electron microscope.The results show that the fatigue limits of three-layer welded joints are 420 MPa,390 MPa and 400 MPa,respectively.For the first layer of welded joint,the fatigue crack initiation position is the sample surface,and the dislocation configuration is mainly dislocation network and dislocation array.For the second layer of welded joint,the fatigue crack initiation positions are both sample surface and welding defects,and the dislocation configuration is mainly dislocation tangles.For the third layer of welded joint,the fatigue crack initiation positions are sample surface and near-surface welding pores,and the dislocation configuration is mainly dislocation array and tangles.