增材制造GH4169组织及高温性能研究

Study on microstructure and high temperature properties of additive manufacture GH4169

采用激光选区熔化成形(SLM)制备GH4169合金,研究不同取向试样的显微组织、高温拉伸和高温持久性能,并分析试样断口特征。结果表明:经热处理后,试样呈近等轴晶,沿晶界或晶内分布有M_(23)C_(6)、MC碳化物,纵向试样沿沉积方向存在择优取向。横向和纵向试样高温拉伸和高温持久性能均达到了锻件水平,横向试样高温拉伸强度均高于纵向试样,但高温持久强度低于纵向试样,材料具有一定的各向异性现象。缺口试样性能差异规律与光滑试样相同,缺口处的应力集中效应使缺口试样比光滑试样表现出更高的强度。分布于晶界或晶内的碳化物成为裂纹萌生的起点、产生微孔的核心,微孔聚集、长大、连接直至断裂,微观断口未出现传统塑性材料断口上常见的大尺寸韧窝,仅呈现少量细小的韧窝,伴随大量的撕裂棱。

GH4169 alloy was prepared by selective laser melting forming(SLM).The microstructure,high temperature tensile and high temperature durability of the samples with different orientations were studied,and the fracture characteristics were analyzed.The results show that after heat treatment,the samples are nearly equiaxed,with M_(23)C_(6) and MC carbides distributed along the grain boundary or in the grain,and the longitudinal samples are preferentially oriented along the deposition direction.The high temperature tensile strength and high temperature durability of the transverse and longitudinal samples have reached the forging level.The high temperature tensile strength of the transverse samples is higher than that of the longitudinal samples,but the high temperature lasting strength is lower than that of the longitudinal samples.The performance difference of notched sample is the same as that of smooth specimen.The stress concentration effect at the notch makes notched sample show higher strength than smooth sample.The carbide distributed in the grain boundary or in the grain becomes the starting point of crack initiation and the core of micropores.The micropores gather,grow,connect until fracture.The microscopic fracture does not show the large-size dimples common in the fracture of traditional plastic materials,but only a few small dimples accompanied by a large number of tearing edges.