摘要
利用高能等离子束对球墨铸铁表面进行表面合金化高钒高速钢涂层,获得了从表至内依次为类高钒高速钢-白口铁-球铁的梯度材料。采用OM,SEM,XRD和显微硬度计对球墨铸铁改性层的组织形貌、显微硬度进行了分析。研究结果表明:等离子改性层主要分为合金层,熔凝层,热影响区和基体,其中合金区组织主要为团球、块状的MC、M7C3、Cr23C6碳化物以及马氏体和残留奥氏体;熔凝区为亚共晶白口铸铁层而热影响区出现了包围石墨球的马氏体壳组织。合金层最高硬度为HV0.2956.5,是基体的4.78倍。合金层硬度的增加主要归于硬质碳化物相的析出强化,以及合金元素的固溶强化和等离子束快速加热快速凝固导致的细晶强化。
A high vanadium high-speed steel （HVHSS） coating was alloyed evenly on a ferrite-matrix ductile iron by plasma transferred arc （PTA）. A structure with a similar high vanadium high-speed steel - white cast iron - ductile iron from outside to inside of the surface of ductile iron was fabricated. The microstructure and hardness distribution of the PTA-alloyed layers were investigated by using optical microscope （OM）, scanning electron microscope （SEM） with energy dispersive spectroscopy （EDS）, X-ray diffraction （XRD） and microhardness tester, respectively. The results show that the cross-section consists of four regions： alloyed zone （AZ）, remelted zone （RZ）, heat affected zone （HAZ） and unaffected substrate （SUB）. The AZ consists of MC-type carbides, M7C3 ,Cr23C6, martensite and residual austenite and the RZ has a typical microstructure of hypoeutectic white iron. The martensite shells are also found in the HAZ. The maximum microhardness of PTA-alloyed layer is HV0.2 956.5, which is 4.78 times as the substrate. The improvement is attributed to the formation of mixed hard-carbides and the solution strengthening by the alloying elements and grain refining through the rapid cooling.
出处
《铸造》
CAS
CSCD
北大核心
2014年第7期637-641,共5页
Foundry
关键词
等离子束
表面合金化
球墨铸铁
高速钢
显微硬度
plasma beam
surface alloying
ductile iron
high-speed steel
microhardness
