脉冲宽度对激光熔覆FeSiB涂层组织与硬度的影响

摘要

High-density coating with FeSiB amorphous ribbons as cladding materials on the surface of mild steel was fabricated by laser cladding.The effect of different pulse widths on formability,microstructure and microhardness of the coatings was analyzed by optical microscope(OM),X-ray diffractometer (XRD),scanning electron microscope (SEM) and microhardness tester.The results show that with the increase of the pulse width,the coating dilute rate rises;the tendency of crack increases and the crack originates from surface to the interface;the degree of crystallization increases and crystallization phases are α-Fe,Fe2B and Fe3Si,fusion zone width increases and the trend of columnar crystals along the epitaxial growth becomes bigger and bigger;the microhardness firstly increases and then decreases.When pulse width is 3.2ms,the structure of the coating is compact,no hole defects,the interface exhibits a good metallurgical combination and the dilute rate is low about 23.2％.Average microhardness of the coating reaches 1192HV,which is about 10 times as much as the substrate.%以FeSiB非晶带材为熔覆材料,采用激光熔覆在低碳钢表面制备高致密度涂层,利用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)、显微硬度仪等研究不同脉冲宽度对激光熔覆涂层成形、组织特征及硬度的影响.结果表明:随脉冲宽度增大,涂层稀释率升高;裂纹倾向增加,裂纹源萌生由表面到界面处;晶化程度升高,结晶相为α-Fe,Fe2B和Fe3Si;熔合区宽度增大,柱状晶沿外延生长趋势更大;显微硬度先增加后减小.当脉冲宽度为3.2ms时,涂层结构致密,无孔洞缺陷,界面呈良好的冶金结合,稀释率低,为23.2％,涂层平均显微硬度达1192HV,约为基材的10倍.