W6钢电子束焊后表面重熔硬化

Hardening effect of electron beam surface remelting on W6 steel

高速钢是一种具有高硬度、高耐磨性的特殊工具钢.对于进行过球化退火的高速钢,其显微硬度损失较大,严重影响其应用.为恢复球化退火W6Mo5Cr4V2高速钢表面的显微硬度,同时保证其内部良好的韧性不受影响,采用电子束表面重熔对其表面进行硬化.结果表明,重熔表面整体呈现平整光滑状态,存在小尺寸熔坑,重熔层内部呈现胞状树枝晶组织,主要由马氏体、残余奥氏体、晶间网状M2C共晶碳化物以及细棒状MC碳化物组成,呈现不均匀的条带状分布,在重熔区边界存在未熔碳化物,在重熔区中心区域碳化物均匀性较高,并对晶间碳化物的形成机理进行了分析.经过电子束表面重熔,由于晶内针状马氏体以及晶界脆性碳化物生成,W6Mo5Cr4V2高速钢表面的显微硬度由283 HV提高到800 HV以上,母材的显微硬度恢复效果显著.

High-speed steel is a kind of special tool steel with high hardness and wear resistance.The microhardness loss of high-speed steel that is subjected to spheroidizing annealing is large,which significantly affects its application.In order to increase the microhardness of spheroidal annealing W6 Mo5 Cr4 V2 high-speed steel surface,and to ensure its good internal toughness,the electron beam surface remelting is used to harden the surface.The remelting surface is flat and smooth with small craters.Cellular dendrites are observed in the remelting layer,which is mainly composed of martensite,residual austenite,M2 C eutectic carbide,and fine rod-shaped MC carbide,the formation process and types of intercrystalline carbides are analyzed.After electron beam surface remelting,the microhardness of the W6 Mo5 Cr4 V2 high-speed steel surface is increased from 283 HV to more than 800 HV,indicating the prominent recovery effect of microhardness.