摘要
目的 研究热等静压处理对选区激光熔化(SLM)成形不同沉积方向Inconel 718合金试样显微组织和力学性能的影响规律,提升Inconel718合金的综合力学性能。方法 采用SLM技术制备平行沉积方向和垂直沉积方向的Inconel 718合金试样,并对试样进行热等静压(HIP)处理和热等静压+固溶时效(HIP+HT)处理。利用金相显微镜(OM)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)和电子背散射衍射(EBSD),对合金的显微组织、断口形貌、物相组成、晶粒形貌及取向进行分析。对试样进行显微硬度和拉伸强度性能测试,对比分析不同沉积方向SLM、HIP及HIP+HT试样的显微硬度、拉伸强度、屈服强度以及断口延伸率。结果 SLM成形的Inconel718合金经热等静处理后,平行方向的晶粒形态由柱状晶转变为等轴晶,晶粒尺寸增大,并伴随有孪晶形成。晶界处的Laves相基本溶解,同时有许多MC碳化物在γ基体中析出。不同处理状态下平行方向试样的拉伸强度、屈服强度和硬度值均小于垂直方向。平行和垂直方向SLM成形件的拉伸强度σb分别为996.3MPa和1051.1MPa,热等静压处理后σb分别提高至1151.5 MPa和1167.6 MPa。对比3种处理工艺,垂直方向的HIP+HT试样具有最高的强度和硬度,且整体性能优于锻件技术标准要求。断口分析表明,3种试样的断口均呈韧性断裂。结论 热等静压处理可以消除裂纹和孔隙等缺陷,促进不同方向的显微组织均匀化,从而综合提升SLM工艺制备的Inconel 718合金的力学性能。
The purpose of this paper is to comprehensively improve the mechanical properties of SLMed Inconel 718 alloy in different building directions by studying the influence of hot isostatic pressure treatment on the microstructure and mechanical properties in the parallel and perpendicular to building direction. Inconel 718 alloy samples were prepared by selective laser melting technology, and SLMed samples were treated by hot isostatic pressure and solid solution aging heat treatment. The microstructure, fracture morphology, phase composition, grain morphology and orientation of the alloy were analyzed by means of metallographic microscope(OM), scanning electron microscope(SEM), transmission electron microscope(TEM), X-ray diffractometer(XRD) and electron backscattering diffraction(EBSD). The microstructure hardness, tensile strength, yield strength and elongation rate of different forming direction of SLM formed and hip treatment and HIP+HT treatment were analyzed. The results indicated that the grain morphology of SLM Inconel 718 alloy along the building direction had changed from columnar to equiaxial crystal, and the grain size had increased, accompanied by twin formation after the heat isostatic treatment. Meanwhile, most Laves phase around grain boundary had disappeared, and many MC carbides were precipitated in γ matrix. The strength and hardness of the parallel to the building direction were greater than those perpendicular to building direction after different treatment. The tensile strength of the SLMed Inconel 718 alloy parallel and perpendicular to the building direction was 996.3 MPa and 1051.1 MPa respectively. After HIP treatment, the tensile strength in parallel and perpendicular to the deposition direction was increased to 1151.5 MPa and 1167.6 MPa, respectively. Compared with SLM and HIP specimens, HIP+HT specimens perpendicular to the building direction exhibited the highest tensile properties, which was superior to the technical standard values of forgings. The fracture analysis shows that the fracture is ductile in three conditions.Hot isostatic treatment can change grain morphology and orientation in different directions, eliminate cracks and pores and other defects, so the mechanical properties of Inconel 718 alloy fabricated by SLM can be improved comprehensively.
作者
罗浩
李小强
潘存良
曾克里
何鹏江
潘超梅
李晖云
LUO Hao;LI Xiao-qiang;PAN Cun-liang;ZENG Ke-li;HE Peng-jiang;PAN Chao-mei;LI Hui-yun(National Engineering Research Center of Near-net-shape Forming for Metallic Materials,South China University of Technology,Guangzhou 510640,China;Institute of New Materials,Guangdong Academy of Sciences,Guangzhou 510650,China;Dongguan Hyper Tech Co.,Ltd.,Dongguan 523808,China)
出处
《表面技术》
EI
CAS
CSCD
北大核心
2022年第3期333-341,362,共10页
Surface Technology
基金
广东省重点领域研发计划(2018B090905001)
广东省科技计划项目(2018B090905002,2020B090923001)
东莞市引进创新科研团队计划(201536000200027)。