激光选区熔化4J36因瓦合金成形工艺及性能

Forming Process and Property of Selective Laser Melted 4J36 Invar Alloy

通过单因素试验分析了不同激光功率、扫描速度下激光选区熔化(SLM)成形4J36因瓦合金试样的致密度、显微组织和力学性能,确定了最优成形工艺,并研究了成形态和热处理态试样的热膨胀系数。结果表明:4J36合金SLM最优工艺为激光功率250 W、扫描速度1000 mm/s、扫描间距0.1 mm、层厚0.04 mm,此工艺下,试样致密度最高,达到99.53%,成形态横向试样抗拉强度为479 MPa,断后伸长率为35%,纵向抗拉强度为455 MPa,断后伸长率为38.5%;固溶+回火+时效热处理后试样横、纵向抗拉强度有所降低,塑性提高,横、纵向断后伸长率分别可达44%、48.5%,整体优于锻件热处理态;SLM成形态和热处理态试样保留了4J36因瓦合金低热膨胀系数特性,成形态在100℃以下热膨胀系数均为负值,热处理态在70℃以下均为负值,较传统加工的热处理态制件的热膨胀系数更低。

The density,microstructure and mechanical properties of 4J36 invar alloy formed by selective laser melting with different laser power and scanning speed were analyzed by single factor test.The optimal forming process was determined.The thermal expansion coefficient of the formed and heat treated samples was studied.The results show that the optimum SLM process of 4J36 alloy is laser power of 250 W,scanning speed of 1000 mm/s,scanning distance of 0.1mm and layer thickness of 0.04mm.Under this process,the density of the sample is maximum of 99.53%,the tensile strength of the horizontal sample in formed state can reach 479 MPa,the elongation is 35%,the tensile strength of the vertical sample is 455MPa,and the elongation is 38.5%.The strength of the sample in horizontal and vertical directions after solution+tempering+aging heat treatment is slightly lower,the elongation is improved and it reaches 44%for the horizontal sample and 48.5%for the vertical sample,which is better than that of the heat-treated forging.The low coefficient of thermal expansion(CTE)of4J36 invar alloy is retained in samples in SLM formed and heat treated states,and the CTE of the sample in formed state is negative below 100℃,and the CTE of the sample after heat treatment is negative below 70℃,which is lower than that of the traditional machining+heat treated parts.