超高速激光熔覆316L涂层的组织与性能

采用超高速激光熔覆技术，在45钢轴上制备了316L涂层；利用扫描电镜(SEM)观察了涂层的显微组织，用能谱仪(EDS)和X-射线衍射(XRD)进行元素及物相分析，并测试了涂层的显微硬度和耐磨性。结果表明，超高速激光熔覆技术的光斑直径小、搭接率高，故涂层的平整度高；能量密度高(约9×10⁴W/cm²)，粉末完全熔化，故涂层的致密度高；熔体的体量小，冷热转换速度快，过冷度△T大，晶粒细化明显；涂层中下部由快速凝固产生的细小枝晶以及枝晶间共晶相组成，中上部的晶粒逐渐向等轴晶粒转变；搭接分界处和熔覆层/基材界面处，两边的晶粒尺寸差异较大；激光对基材有一定的稀释作用；涂层厚度不均匀，与基材结合良好，为冶金结合；316L涂层物相由γ-Fe、Cr_0.19Fe_0.7Ni_0.11、Fe₆₃Mo₃₇组成；由于细晶强化和第二相强化机制，316L涂层的平均硬度(634.12HV_0.5)是45钢基体的3.07倍；耐磨性提高了31.8%，其...

Microstructure and properties of extreme high speed Laser cladding 316L coating

Using extreme high speed laser cladding technology, 316L coating was prepared on 45 steel shaft. The microstructureof the coating was observed by scanning electron microscope (SEM), elemental and phase analyses werecarried out by energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the microhardness and wear resistanceof the coating were tested. The results show that the extreme high speed laser cladding technology has asmall spot diameter and a high overlap rate, so the flatness of the coating is high. The energy density is high (about 9×104 W/cm2), and the powder is completely melted, so the coating has a high density. The volume of the melt is small,the heat and cold conversion speed is fast, the degree of undercooling ΔT is large, so the grain refinement is obvious.The middle and lower parts of the coating are composed of small dendrites produced by rapid solidification and interdendriticeutectic phases, the middle and upper parts grains gradually transform to equiaxed grains. At the overlapboundary and at the cladding layer/substrate interface, there is a large difference in grain size on both sides. The laserhas a certain dilution effect on the substrate. The coating thickness is uneven, but it is well metallurgical bonded with the base material. The phase of the 316L coating is composed of γ -Fe, Cr0.19Fe0.7Ni0.11, Fe63Mo37. Due to fine grainstrengthening and second phase strengthening mechanism, the average hardness of the 316L coating (634.12HV0.5) is3.07 times that of the 45 steel substrate. The wear resistance is increased by 31.8%, and the main wear mechanism isabrasive wear.