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。

The influence factor of the creep rupture properties of the materials in dissimilar material joints was studied using a transition layer and weld built with the same welding parameters as for real structures with the same base and weld materials. Creep rupture tests were conducted on welded joints at different temperatures and stresses. Most fractures appeared at the fusion zones between the transition layers. Metallographic observations, micro hardness tests, chemical composition analyses and scanning electron microscope (SEM) observations show a softened layer at the fusion zone of the transition layer which causes strain concentrations and easier fracture. The large Cr gradient between the transition layers leads to carbon migration and hardness reductions that eventually result in a softened layer. In addition, the crystallization orientation between the fusion zone and other areas in the transition layer is found to differ, which will also reduce the creep rupture strength. Thus, the creep rupture properties of dissimilar joints can be improved by optimizing the weld composition and the welding process.