选择性激光熔化17-4PH合金的成形研究

Study on Selective Laser Melted 17-4PH Alloy

对17-4 PH合金选择性激光熔化成形(SLM)热处理前后的力学性能和微观组织进行了研究,并与锻造零件进行了对比。结果表明,SLM成形方向不同和热处理对成形试样力学性能和微观组织有显著的影响。0°成形方向力学性能明显优于30°成形方向试件,热处理后SLM试件的性能有显著的提高,同等热处理条件下的SLM试件拉伸强度优于锻造件。不同成形方向成形过程中热经历的不同是引起了成形试件微观组织和力学性能之间存在差异的主要原因。缺陷对拉伸强度和屈服强度没有显著的影响,对断裂延伸率影响较大。17-4 P H SLM成形件微观组织由马氏体和奥氏体混合二重组织组成,热处理后的组织比直接沉积成形的组织更加均匀。

This paper studies the mechanical properties and microstructural features of the selective laser melting（SLM）17-4 precipitation hardening（PH） alloy as well as their comparison to conventionally wrought materials. The study investigates the effects of different building direction and post-fabrication heat treatment（solution and aging） on the mechanical and microstructural characteristics of samples fabricated by SLM. The results showed that the building direction and heat treatment have a noticeable effect on tensile properties. The 0 ° building direction have better properties than 30°, ultimate tensile strength of SLM-produced 17-4 PH is found to be higher than those of wrought materials under the same heat treatment. The 30°built samples express a distinctively different thermal history relative to the 0° ones, which causes the difference of mechanical properties and microstructural features. Presences of defects have no significant effects on the tensile strength and yield strength, but they have a remarkable effect on the elongation to failure. Microstructural examination reveals a dual phase mixture of martensite and austensite, heat treatment made the microstructure more homogenized compared to as-deposited samples.