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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。
Aiming at the problems of high cost and easy dissolution of WC particles, a mixed powder consisting mainly of tungsten powder and carbon powder was prepared. The surface strengthening of 45 steel was studied by the high temperature reaction of molten steel. Sample preparation using V-EPC vacuum infusion molding infiltration process. The prepared surface alloy layer has compact structure with no obvious defects of pores, shrinkage cavity, slag inclusion and delamination. Microstructure observation shows that the sample consists of three layers of the surface alloy layer, the intermediate transition layer and the lower substrate layer. The surface alloy layer consists of a dendritic matrix and a network of eutectic distributed between dendrites, with no WC particles present. EDS and XRD analysis showed that there are two types of reticular eutectic carbides, one is tungsten-rich WC or W2C and the other is iron-rich M7C3. A small amount of tungsten metal of different sizes is distributed at the bottom of the surface alloy layer Granules. The transition layer consists of a large number of pearlite, a small amount of ferrite and mesh carbide composition; matrix by the ferrite and pearlite composition.