激光快速成形304不锈钢试件组织与拉伸断口特性分析

用激光快速成形(LRF)技术制备304不锈钢拉伸试样,并对试样进行拉伸。利用光学显微镜观察了试样表面显微组织;利用扫描电镜(SEM)观察了试样断口的形貌特征,并用能谱仪(EDS)分析了取样点处的化学成分。结果表明,所制备试样显微组织晶粒细小,具有定向凝固的特征,在成形件内部存在微细观孔洞与裂纹。在拉伸断裂试样中,断口呈现韧性断裂的特征,断口部分区间氧、硅含量较高,形成金属化合物夹杂,使材料的力学性能变差。

Analysis on Microstructure and Tensile Fracture Characteristic of 304 Stainless Steel Specimens Made by Laser Rapid Forming

With the technique of laser rapid forming(LRF),tensile samples of 304 stainless steel are prepared,on which tensile test is done.The surface is observed by optical microscope,the fracture morphology of the specimens is observed by scanning electronic microscopy(SEM),and chemical compositions of sampling points are analyzed by energy dispersive spectrometer(EDS).The results show that the sample′s microstructure contains small grains with unidirectional solidification characteristic,which form micro-holes and micro-cracks inside the formed parts.In specimens of tensile fracture,there are ductile fracture characteristics,and the contents of oxygen and silicon in some area of fracture surface are higher.These worsen the mechanical properties of the specimens.