摘要
为提高车用304不锈钢的耐磨性,采用激光熔凝技术对车用304不锈钢表面进行强化.通过金相显微镜、显微硬度计、摩擦磨损试验机、扫描电镜及能谱仪分别对熔凝层宏观形貌、微观组织、显微硬度、磨痕形貌及磨损机理进行分析.结果表明,激光熔凝后,熔凝层无气孔、裂纹等缺陷,组织均匀致密.激光熔凝急热急冷的特性,显著细化了熔凝层的显微组织,熔凝层主要由树枝晶和等轴晶组成.细晶强化是熔凝层硬度提升的主要原因,熔凝层的显微硬度约为281 HV,相较于304不锈钢基体提升了约50％.由于硬度的提升,熔凝层的摩擦因数和磨损率均有下降,分别为0.544和2.46×10-5(N·m).熔凝层磨损机理为磨粒磨损.激光熔凝可有效提升304不锈钢的硬度和耐磨性.
Abstract
Laser melting technology was employed to enhance the surface of 304 stainless steel,aiming to improve its wear re-sistance.The morphology,microstructure,microhardness,wear morphologies,and wear mechanism of the resulting melting layer were comprehensively analyzed using optical microscopy,microhardness testing,friction and wear testing,scanning elec-tron microscopy,and energy dispersive spectroscopy.The results showed that the melting layer had no defects such as pores and cracks after laser melting,and the microstructure was uniform and dense.Due to the rapid heating and cooling process of laser melting,the microstructure of the melting layer was significantly refined,and the melting layer was mainly composed of dendrites and equiaxed crystals.Fine grain strengthening was the main factor for the hardness improvement of melting layer,and the microhardness of melting layer was about 281 HV,which was about 50％higher than that of 304 stainless steel sub-strate.With the increase of hardness,the friction coefficient and wear rate of the melted layer decreased to 0.544 and 2.46X 10-5(N·m),respectively.The wear mechanism of melting layer was abrasive wear.Laser melting effectively improved the microhardness and wear resistance of 304 stainless steel.
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