高功率光纤激光熔化成形IN718的工艺及性能Process and Properties of IN718 Formed by High-power Fiber Laser Melting

为研究选择性激光熔化(selective laser melting,SLM)成形工艺参数对镍基高温合金IN718致密度、微观组织和显微硬度的影响,借助FORWEDO LM180型SLM成形机采用不同工艺参数制备了分析试样,通过维氏硬度测试,光学和扫描电镜观测以及X射线检测方法对试样进行了测试分析。结果表明:随激光能量密度提高(激光功率起主导作用),成形试样孔隙缺陷减少,致密度显著提高;在较大激光能量密度下,合金试样微观组织生长趋于均匀,晶粒更加细小;提高激光扫描速率,造成激光辐射和冷却时间变短,合金微观组织生长方向变化显著;SLM工艺复杂的传热特点影响试样组织形貌的复杂程度;合金试样的显微硬度随着组织细化和致密化而提高。

The influence of process parameters forming nickel-based superalloy IN718 by Selective Laser Melting(SLM) on the densification, microstructure and microhardness was studied. Four nickel-based superalloy IN718 samples were fabricated in various processing parameters using FORWEDO LM-180 SLM system. The samples were analyzed with Vickers hardness measurement, SEM and XRD. The results show that the increase of the laser energy density causes the decrease of porosity defects and the significant improvement of their relative density. Under higher laser energy density, microstructures grow more evenly and particles become finer. When the laser scanning speed increases, the laser radiation and cooling time get shorter, so the growing direction of microstructures is changed sharply. Complex heat transfer effects the complexity of the microstructure. Higher extent refinement of grain and densification improve the microhardness.

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