再加热对Fe_3A1/18-8扩散焊界面附近组织结构的影响

Effect of re-heating on microstructures near Fe_3A1/18-8 diffusion bonding interface

Fe3A1/18-8扩散焊界面不均匀地分布着第二相析出物,特别是交界面处连续分布的析出相族可能直接诱发裂纹,是引起接头失效的重要因素。对Fe3A1/18-8扩散焊接头进行再加热,采用扫描电镜、能谱分析、X射线衍射等对析出相及界面相结构进行分析。结果表明,再加热后界面析出相细化且形状规则,均匀分布于Fe3A1/18-8界面,析出相族消失。界面附近的显微硬度降低,不存在高硬度脆性相。

There unevenly distributed second-phase precipitations at the Fe3A1/18-8 (stainless steel) diffusion bonding interface directly. Especially, the continuous precipitation groups at the boundary could induce welding cracks, which was the main factor caused the failure of the Fe3A1/18-8 diffusion-bonded joint. The Fe3A1/18-8 diffusion-bonded joint was re-heated and the precipitation and phase constituent of the interface were analysed by means of scanning electron microscope, energy dispersive spectrum and X-ray diffraction. The results indicated that the precipitation distributs evenly at the Fe3A1/18-8 diffusion bonding interface due to the effect of re-heating and the precipitation becomes tiny and regular. The continuous precipitation groups are liquated. The microhardness near the Fe3A1/18-8 diffusion bonding interface decreases and there are no higher-microhardness brittle phases after re-heating.