脉冲等离子弧快速成形Inconel 625组织性能研究

Microstructure and Mechanical Properties of Inconel 625 Components Deposited by Pulsed Plasma Arc Rapid Prototyping

研究了脉冲等离子弧快速成形Inconel 625镍基高温合金零件的组织特征及力学性能,重点分析了沉积态组织中相析出规律及分布特点。结果表明,沉积态的组织以胞状树枝晶为主,具有较强生长取向性的外延枝晶组织特征,层与层结合处呈现更细小胞状枝晶特征。由于较快的冷却速率,在整个成形零件包括层与层的结合处并未出现严重的显微偏析现象。通过多种分析手段证实了大量不规则形状的弥散Laves相颗粒分布在枝晶间,MC碳化物(包括NbC,TiC)分布在枝晶间及晶界,以及少量针状相δ(Ni3Nb)的析出。力学性能测试结果表明,显微硬度在整个沉积零件分布较为均匀,在260～285HV0.2范围内,在零件的底部及层层的结合处由于更细小的组织而呈现更高的硬度值。由于析出相的弥散强化作用,零件的抗拉强度最高达到750MPa,同时伸长率可达到50%。

The microstructure and mechanical properties of Inconel 625 component deposited by pulsed plasma arc rapid prototyping were investigated.The precipitation principle and distribution characteristics of phases in deposits were analyzed.The results indicated that the as-deposited samples exhibited homogenous cellular dendrite structure in nature,which grew epitaxially along the deposition direction.The microstructure of the interface regions between deposited layers exhibited refined structure.The composition distribution in the whole sample was pretty uniform and no significant segregation occurred.Some intermetallic phases such as Laves phase,some minor MC（NbC,TiC） and needle-like δ（Ni3Nb） were observed in γ-Ni matrix.Disperse MC particles precipitates in interdendritic and grain boundary.Micro-hardness measured at various location（including transverse plane and longitudinal plane） revealed hardness in the range of 260-285HV0.2.Due to highly refined structure,micro-hardness at the interface region is slightly higher than the other regions.Ultimate tensile strength of Inconel 625 sample deposited as short raster pattern was found to be 750MPa,and the percentage elongation was found to be 50%.