采用选区激光熔化技术成形Inconel625高温合金(IN625)试样,探讨激光能量密度对试样孔隙和裂纹等缺陷的影响,并分析最佳相对密度试样的组织和力学性能。结果表明:当能量密度为50~78 J·mm -3时,试样的相对密度达到99.5%以上;当激光能量密度为75 J·mm -3时,成形件接近完全致密状态;当能量密度较低时,试样内出现未熔粉末和裂纹;当能量密度较高时,试样中出现不规则孔洞和细小孔隙。最佳相对密度的成形件显微组织中存在胞状晶和柱状晶,晶粒的平均粒径为10~30 μm,亚晶的数目较少,晶粒生长方向出现少量<001>择优取向;拉伸断裂模式为混合断裂,拉伸断口上出现了大量、细小的韧窝;成形件的显微硬度、抗拉强度、屈服强度和延伸率分别为(327±3) HV、(930±5) MPa、(700±5) MPa和29.5%。

In this study, Inconel 625 superalloy (IN625) samples were formed using the selective laser melting (SLM) technology. The effects of the process parameters on defects, such as pores and cracks, were investigated. Then, the microstructure and mechanical properties of the samples under the optimal relative density were analyzed. Results show that the samples has a relative density of over 99.5% when the energy density is 50-78 J·mm ^-3. An energy input of approximately 75 J·mm ^-3 is required to approach the completely dense state. The sample displays cracks and un-melting powder owing to the low energy density. When the energy density is high, irregular and fine pores appear. The IN625 sample morphology shows cellular and columnar grains. Meanwhile, the average size of grains is 10-30 μm and the number of subgrains is small. The <001> crystallographic orientation is the preferred direction for the IN625 samples. A large number of small dimples appear on the mixed fracture. The microhardness, tensile strength, yield strength, and elongation are (327±3) HV, (930±5) MPa, (700±5) MPa, and 29.5%, respectively.