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为了研究异种钢焊接接头高温持久性能的薄弱环节和影响因素,采用与实际结构相同的母材和焊丝,按照实际的焊接工艺制造了含有过渡层的试板模拟件接头。对接头进行高温持久试验发现,绝大多数试样都在过渡层层间的熔合区发生断裂。通过金相观察、显微硬度测试、成分分析和扫描电镜(SEM)观察等手段,证明过渡层内的熔合区存在软化层,导致了应变集中,因此容易开裂。软化层的形成是由于过渡层层间Cr元素差异较大,使C元素向较高Cr含量一侧迁移,从而形成贫碳区,使硬度降低。过渡层熔合区存在结晶方向的差异,也会对接头持久性能造成不利影响。优化焊丝合金成分和改进焊接工艺可提高异种钢焊接接头的持久性能。
In order to study the weak links and influential factors of the high-temperature durability of dissimilar steel welded joints, the basement and the welding wire with the same physical structure were used to manufacture the joint of the test board with transitional layer according to the actual welding process. Durability testing of the joints showed that most of the specimens were fractured in the fusion zone between the transitional layers. Metallographic observation, microhardness test, composition analysis and scanning electron microscopy (SEM) observation show that the fusion zone in the transitional layer has a softening layer, which leads to the concentration of strain and therefore easy to crack. The formation of the softened layer is due to the large difference in the Cr content between the transitional layers, causing the C element to migrate to the higher Cr content side, thereby forming a carbon lean zone and reducing the hardness. The difference in crystallographic orientation at the fusion zone in the transition zone can also adversely affect the durability of the joint. Optimizing the composition of the wire alloy and improving the welding process improve the durability of dissimilar steel welded joints.