航天高强不锈钢LMD成形缺陷分析及控制

为明晰航天高强不锈钢激光熔化沉积成形过程基础科学问题,推动其在航天液体火箭发动机领域的应用进程,针对航天高强不锈钢LMD成形过程中常见表面焊瘤、气孔、熔合不良等缺陷的形貌特征及产生机理进行深入分析,并提出对应的控制措施:通过优化边框扫描速度促进熔覆道的流动变形,极大减少了成形件侧表面及倾斜面的焊瘤缺陷; 使用PREP方...

Defect analysis and control in aerospace high strength stainless steel by laser melting deposition

In order to clarify the basic scientific problems of laser melting deposition forming process of aerospace high strength stainless steel,to promote its application in the field of aerospace liquid rocket engine,the defect types and mechanism of aerospace high strength stainless steel by laser melting deposition were analyzed.Besides,the corresponding control measures were put forward.First,the flow deformation of cladding channel was promoted by optimizing the scanning speed of border,the defects of weld nodules on the side surface and inclined surface of the formed part are greatly reduced.Second,the PREP method of powder preparation was used instead of the current GA method,the porosity of the formed specimen was reduced to less than 0.1%,and the stomatal defects were basically eliminated.Finally,the method of increasing the"layer remelting capacity"and decreasing the"gully"height between adjacent cladding channels was adopted,the defects of bad internal fusion were eliminated.