研究了两种不同Cr含量的马氏体球墨铸铁磨球(Φ110 mm)内外层微观组织和硬度.结果显示,磨球的表层组织以马氏体和石墨球为主,不含Cr的磨球心部组织以片层状的珠光体为主,还有石墨和少量铁素体;加入0.4%Cr后,磨球心部以马氏体为主,含一定数量的碳化物.硬度测试结果表明不含Cr磨球外层硬度约HRC50,心部硬度仅HRC30,内外层硬度相差HRC20;加Cr后因引入了碳化物,外层硬度提高到HRC59,而内外层硬度差仅HRC3.与高铬铸铁磨球相比,含Cr的马氏体球墨铸铁磨球具有较好的综合性能,在较大冲击环境下具有更好的应用前景.%The microstructure and hardness for a martensitic ductile iron grinding ball (Φ110mm) with two different Cr content was investigated. The results shown that in surface layer of grinding ball there are mainly martensite and graphite. However, in spite of graphite and a small amount of ferrite there consist of mainly lamellar pearlite in core region for grinding ball without Cr content. After addition of 0.4% Cr, the core of grinding ball is mainly composed of martensite and contain a small amount of carbides. Hardness test results show that the hardness of the surface layer of non-Cr grinding ball is about HRC50 and the hardness of core is HRC30, which implies that the difference between surface and core hardness is HRC20. After addition of Cr, the surface hardness of grinding ball increases to HRC59 and the difference between surface and core hardness is only HRC3. Compared with high chromium casting iron grinding ball, the Cr-containing martensitic ductile iron grinding ball has better comprehensive performance and has better application prospect in the larger impact environment.
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