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采用高速摄像机和光学显微镜构成的摄像装置对激光焊接熔池后端的凝固行为进行高速高倍摄像,详细记录了柱状晶从液态熔池后部析出过程以及残留在已析出柱状晶周围的液体金属的凝固行为.采用液体Sn急冷将焊接过程中正在凝固的焊缝金属冷冻保存到室温,并与高速高倍摄像观察到的熔池后端的凝固行为进行了对比分析.对3种奥氏体不锈钢材料焊缝凝固过程中残留液体金属的存在范围进行了观察和比较.在线观察到的残留液体金属是焊缝金属凝固过程中固/液相共存区间的初始部分,即与熔池相连的较多的液体金属.针对3种不锈钢材料在线观察到的残留液体金属的存在范围与热裂纹实验获得的热裂纹敏感性有较好的对应关系,为发展一种通过在线观察判断材料凝固热裂纹敏感性的方法提供了实验依据.
A high-speed high-power camera was used to image the solidification behavior of the laser welding pool at the back of the molten pool. The detachment of the columnar crystals from the back of the liquid pool and the solidification of the liquid metal remained around the precipitated columnar crystals were recorded in detail. Behavior of the weld metal was frozen by liquid Sn quenching to the freezing temperature of the weld metal being solidified during the welding process and compared with the solidification behavior of the rear end of the molten pool observed by high-speed high magnification photography.The weld of three austenitic stainless steel materials The scope of the residual liquid metal during solidification was observed and compared.The residual liquid metal observed online was the initial part of the solid / liquid phase coexistence zone during the solidification of the weld metal, that is, the more liquid metal The presence of residual liquid metal observed online for the three stainless steel materials has a good correspondence with the susceptibility to hot cracking obtained from the hot cracking experiment and is to be provided for the development of a method for judging the susceptibility of materials to solidification hot cracking by on- The experimental basis.