激光重熔对选区激光熔化成形4Cr5MoSiV1钢组织和性能的影响

Effect of Laser Remelting on Microstructure and Properties of 4Cr5MoSiV1 Steel Fabricated by Selective Laser Melting

目的优化选区激光熔化(Selective Laser Melting,SLM)成形4Cr5MoSiV1钢的激光重熔工艺,综合提升SLM成形4Cr5MoSiV1钢的力学性能。方法通过调整SLM成形过程中的激光重熔工艺参数成形4Cr5MoSiV1钢试样,采用扫描电镜、显微硬度计、万能材料试验机和摩擦磨损试验机测试分析试样的表面形貌、显微组织、显微硬度、抗拉强度、断后伸长率和耐磨性。结果SLM成形4Cr5MoSiV1钢试样表面的飞溅颗粒、杂质颗粒和弧形波纹数量较多,其显微硬度为599HV,抗拉强度为1050.2MPa,断后伸长率为9.5%,磨损率为1.309×10-10kg/(N·m)。4Cr5MoSiV1钢试样经激光重熔后,其冶金质量明显改善,显微硬度、抗拉强度、断后伸长率和耐磨性均提高,且各项力学性能间呈正相关关系。冶金质量和细晶强化作用共同决定4Cr5MoSiV1钢试样的力学性能水平,且随激光重熔线能量密度增加,试样的力学性能均表现为先升高后降低的趋势。当激光重熔线能量密度为238 J/m时,试样的力学性能最高,其显微硬度为645HV,抗拉强度为1430.7 MPa,断后伸长率为16.9%,磨损率为0.354×10-10 kg/(N·m)。SLM成形4Cr5MoSiV1钢试样的断裂机理为脆性解理断裂,激光重熔试样的断裂机理为准解理断裂。SLM成形4Cr5MoSiV1钢试样及激光重熔试样的磨损机制均以粘着磨损和氧化磨损为主。结论SLM成形4Cr5MoSiV1钢试样的最优激光重熔线能量密度为238 J/m,经激光重熔后,试样的冶金质量和力学性能明显提高。

The work aims to optimize the laser remelting process of 4 Cr5 MoSiV1 steel fabricated by selective laser melting(SLM),and comprehensively improve the mechanical properties of 4 Cr5 MoSiV1 steel.The 4 Cr5 MoSiV1 steel sample was fabricated by adjusting the parameters of laser remelting during SLM,and the surface morphology,microstructure,microhardness,tensile strength,elongation after fracture and wear resistance of the sample were tested and analyzed by SEM,microhardness tester,universal material tester and wear tester.The 4 Cr5 MoSiV1 steel fabricated by SLM had many splashing particles,impurity particles and curved corrugations on the surface,with microhardness of 599 HV,tensile strength of 1050.2 MPa,elongation after fracture of 9.5%and wear rate of 1.309×10-10 kg/(N·m).After laser remelting,the metallurgical quality of 4 Cr5 Mo Si V1 steel sample was obviously enhanced,with microhardness,tensile strength,elongation after fracture and wear resistance improved well,and there was a positive correlation between the mechanical properties.The mechanical properties of 4 Cr5 MoSiV1 steel were determined by metallurgical quality and fine grain strengthening.With the increase of line energy density of laser remelting,the mechanical properties of 4 Cr5 MoSiV1 steel increased firstly and then decreased.When the line energy density of laser remelting was 238 J/m,the mechanical properties of the sample were the highest,with microhardness of 645 HV,tensile strength of 1430.7 MPa,elongation after fracture of 16.9%,and wear rate of 0.354×10-10 kg/(N·m).The fracture mechanism of 4 Cr5 MoSiV1 steel fabricated by SLM was brittle cleavage fracture,and that of laser remelted 4 Cr5 MoSiV1 steel was quasi cleavage fracture.The wear mechanism of 4 Cr5 MoSiV1 steel formed by SLM and laser remelting was mainly adhesive wear and oxidation wear.The optimal energy density of laser remelting line for SLM forming 4 Cr5 Mo Si V1 steel sample is 238 J/m.The metallurgical quality and mechanical properties of the sample after laser remelting are obviously improved.