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通过用配置的铁基合金粉末针对不同的基体材料的多次激光熔覆实验,得出熔覆层硬度因熔池的快速冷却得到极大提高。分析显示熔覆层组织主要为富C、B、Si的树枝晶和Fe-Cr马氏体组织。相变体积的膨胀可抵消部分热收缩应变,可得到大面积高硬度无裂纹涂层。随试件体积和热容的增大,熔池冷却速度加快,一次性枝晶减少,马氏体的过饱和度增大,涂层硬度进一步提高。耐磨对比试验证明,铁基合金熔覆层和Cr12淬火基体相比,耐磨性有较大提高。
By using several laser cladding experiments of different base materials with the iron-based alloy powders, it is found that the hardness of the cladding layer is greatly increased due to the rapid cooling of the weld pool. The results show that the microstructure of the coating is mainly dendrite and Fe-Cr martensite with C, B and Si rich. Phase expansion volume expansion can offset part of the thermal shrinkage strain, can be large-area high-hardness crack-free coating. With the increase of specimen volume and heat capacity, the cooling speed of molten pool accelerated, one-time dendrite decreased, the supersaturation of martensite increased, and the coating hardness further increased. Abrasion comparison test shows that compared with Cr12 quenched base, the wear resistance of the iron-based alloy cladding layer is greatly improved.