激光熔化沉积15-5PH沉淀硬化不锈钢组织及拉伸性能

Microstructures and Tensile Properties of 15-5PH Precipitation Hardening Stainless Steel Fabricated by Laser Melting Deposition

利用激光熔化沉积技术制备15-5PH沉淀硬化不锈钢板,利用金相显微镜(OM)、扫描电镜(SEM)、透射电镜(TEM)、电子探针(EPMA)技术,对沉积态组织进行分析,测试沉积态组织的室温拉伸性能。结果表明:激光熔化沉积15-5PH不锈钢沉积态组织由沿沉积增高方向贯穿多层外延生长的柱状晶组成,柱状晶内包含多个细长整齐排列的胞状树枝晶,枝晶内为马氏体组织,枝晶间为铁素体;沉积态组织中弥散分布大量细小的NbC析出相,尺寸12〜20nm;15-5PH不锈钢沉积态组织具有良好的力学性能,纵向抗拉强度和延伸率分别为1128.5MPa和14.0%,横向抗拉强度和延伸率分别为1101 MPa和12.25%。

The 15-5PH precipitation hardening stainless steel is fabricated by laser melting deposition additive manufacturing technique.Microstructures of the as-deposited of the steel are characterized by optical microscopy(OM),scanning electron microscopy(SEM),transmission electron(TEM)and X-ray diffraction(XRD).The tensile properties of the test steel at room temperature are evaluated.The results show that the laser additive manufactured 15-5PH steel mainly consists of rapid directionally solidified columnar grains with interior well aligned cellular-dendrite structure across several deposited layers.The dendrite arm is mainly composed of martensite while the inter-dendritic region consists of ferrite.Extra fine NbC carbides,with size of around 12-20 nm,are randomly distributed in the martensite matrix.The 15-5PH as-deposited steel has good tensile properties,the longitudinal tensile strength and elongation are 1128.5 MPa and 14%respectively,and the transverse tensile strength and elongation are 1101 MPa and 12.25%respectively.