用钨铁粉和碳粉对45钢进行表面合金化

Surface alloying of 45 steel by ferrous-tungsten and carbon powders

针对WC颗粒价格昂贵和易溶解等问题,进行了以钨铁粉和碳粉为主组成的混合粉末,借助钢水的高温反应生成WC对45钢进行表面强化的研究。试样制备采用V-EPC真空消失模铸渗工艺。所制备的表面合金层组织致密,没有明显的气孔、缩孔、夹渣和分层等缺陷。显微组织观察表明,试样由表面合金层,中间过渡层和下部基体层3个层区组成。表面合金层由树枝晶基体和在树枝晶之间分布的网状的共晶体组成,其中无WC颗粒存在。能谱和XRD分析表明,网状共晶碳化物有两种类型,一类为富钨的WC或W2C,另一类为富铁的M7C3;表面合金层底部分布有不同尺寸的少量的金属钨颗粒。过渡层由大量的珠光体、少量的铁素体和网状碳化物组成;基体由铁素体和珠光体组成。

To solve the problem of expensive WC readily decomposing in melted iron,the surface alloying of carbon cast steel with ferrous-tungsten and carbon powder formed to WC on the surface of 45 steel under melten state was investigated.The test samples were prepared with vacuum expendable pattern cast（V-EPC） processes.The alloying layer is dense and without bubbles,shrinkage cavities,inclusions and laminations.The microstructure observation show that the sample from surface towards substrate consists of dendrite matrix and net eutectic between dendrites and no existing WC particles.EDS and X-ray diffraction analyses show that the net carbide eutectic has two kinds micro-structure： one is the W-rich WC or W2C,another is the Fe-rich carbide M7C3 and under the alloying layer exist small amount of W metal particles with different size.The transition zone consists of large amount of pearlite,small part of ferrite and net carbide and the substrate consists of ferrite and pearlite.