热处理对选区激光熔化304L不锈钢组织和力学性能的影响

采用光学显微镜(OM),X射线衍射仪(XRD),扫描电镜(SEM),透射电镜(TEM)等研究了热处理工艺对选区激光熔化(SLM)制备的304L不锈钢微观组织结构与力学性能的影响。结果表明:SLM制备的304L不锈钢的组织结构细小,组织中存在高密度位错、δ铁素体与σ相析出物,其强度和塑性均远高于传统304L不锈钢。对SLM制备的304L不锈钢分别进行1050℃×30 min和1000℃×2 h固溶处理后,其微观组织结构发生了变化,观察到了晶内胞状亚晶组织的长大和析出相的固溶,强度和塑性均有所降低。SLM制备过程产生的大量纳米级胞状亚晶结构,是304L不锈钢具有高强高韧性能的主要原因,析出强化和加工硬化可进一步提高其强度。

Effect of heat treatment on microstructure and mechanical property of 304L stainless steel prepared by selective laser melting

Effect of heat treatment on microstructure and mechanical properties of 304 L stainless steel prepared by selective laser melting(SLM)was studied by means of optical microscope(OM),X-ray diffractometer(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM).The results show that the microstructure of the 304 L stainless steel prepared by SLM is fine and there are high density dislocations,δferrite andσphase precipitates in the microstructure,and the strength and plasticity of the 304 L stainless steel prepared by SLM are much higher than those of traditional 304 L stainless steel.The microstructure of the 304 L stainless steel prepared by SLM is changed after solid solution treatment at 1050℃for 30 min and 1000℃for 2 h,and the growth of cellular subcrystal structure and the solid solution of precipitated phase are observed,the strength and plasticity of the steel decrease.A large number of nanoscale cellular subgrains produced by SLM preparation process are the main reasons for the high strength and high toughness of the 304 L stainless steel,precipitation strengthening and working hardening can further improve the strength of the 304 L stainless steel.