A105钢振动焊接接头的断裂韧度分析

采用阀门用钢A105为试验材料,机械振动焊接与常规埋弧自动焊相结合的对比试验方法,通过残余应力的测试结果可见,振动焊接消除了熔合线附近的应力峰,应力幅值低、分布平缓.从断裂力学的角度分析机械振动对焊接接头韧度的影响,结果表明:焊缝的断裂韧度明显大于热影响区(HAZ);振动焊接工艺下焊缝和HAZ的CTOD(Crack tip opening displacement)值明显高于常规焊接下焊缝和HAZ的CTOD值;且振动焊接使得焊接接头的各部分之间断裂韧度的差别明显缩小,断裂韧度更趋均匀化.经断口的扫描电镜观察可知:振动焊接下焊缝的韧窝密度明显大于常规焊接下焊缝的韧窝密度,且HAZ为整个焊接接头的薄弱环节.

The Analysis of Fracture Toughness of A105 Steel Welded Joint in Vibratory Welding Conditioning

By contrast tests of vibratory submerged-arc welding(V-SAW) and normal SAW(N-SAW) on the valve steel A105,the residual stress was measured.The stress distribution curve shows that the stress peak beside the fusion-line is removed.The amplitude of the stress is decreased and the stress distribution is flat.The effect of mechanical vibration on the toughness of the welded joint was analyzed from the point of view of fracture mechanics.The results indicate that the fracture toughness of the weld is obviously higher than that of HAZ(Heat-affected zone).And the CTOD(Crack tip opening displacement)value of the weld and HAZ under V-SAW condition is greater than that under N-SAW condition.And the difference in different regions of the welded joint is evidently reduced by applying V-SAW.Thereby,the fracture toughness is uniform.From fractography,it can be seen that the dimple density of the weld under V-SAW condition is greater than that under N-SAW condition.And HAZ is a weak region in welded joint.