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钨系白口抗磨铸铁是立足我国资源条件的一种新型抗磨材料。用它制造的金属杂质泵件(叶轮和护板)现场运转试验结果表明,分别接近和达到国外相应的Cr—Ni—Mo合金的抗磨铸铁的使用寿命。尤其是高钨铸铁(W:20～25％)所制的PSV叶轮在北京加气混凝土厂的对比试验中,寿命高达3732小时,达到了2000小时的攻关寿命要求。所以获得如此优异的抗磨性能是由于采取了高合金化措施,获得了以M_6C为主的高硬相并且是镶嵌在马氏体+少量索氏体+残余奥氏的基体上的组织的结果。由于组织的复杂和多样性,所查有关Fe—W—C状态图又差别颇大,为对钨系铸铁,特别是高钨铸铁的组织有所认识我们通过对液淬、半液淬、铸态、热处理及不同冷却速度条件下所获得的工艺试样进行了金相,显微硬度法,X光衍射棺结构等分析法,对钨系铸铁的碳化物形态,相结构,组织的形成,初生M_6C的生长及一些结晶现象提出部分粗浅的实验结果及认识,确定了(C3.0％W>20％)在铸造条件下高钨铸铁是按介稳定状态进行结晶的,初生相为M_6C(Fe_4W_2C或Fe_3W_3C)、二元共晶为M_6C+γ、三元共晶为M_6C+γ+M_3C。根据实验提出了初生M_6C的结晶长大过程以及M_6C的双晶、亚结构组织及带状构造。
Tungsten white cast iron is based on the resources of our country a new type of wear-resistant materials. The metal impurities pump parts (impeller and guard plate) manufactured by it have been tested in the field. The results show that the service lives of the corresponding wear-resistant cast irons of Cr-Ni-Mo alloy are close to and reach respectively. Especially the high-tungsten cast iron (W: 20 ~ 25%) made of PSV impeller in the Beijing aerated concrete plant comparative test, life expectancy as high as 3732 hours, reaching 2000 hours of research life requirements. Therefore, such an excellent anti-wear performance is obtained as a result of taking a high alloying method to obtain a high hardness phase mainly composed of M_6C and being a structure embedded in a matrix of martensite + a small amount of sorbite + residual austenite . Due to the complexity and diversity of the organization, the relevant state diagram of Fe-W-C is quite different. It is known that the microstructure of tungsten-based cast iron, especially high-tungsten cast iron, The microstructure, microstructure and microstructure of the tungsten cast iron were studied by means of metallographic examination, microhardness test and X-ray diffraction analysis. The growth of primary M_6C and some crystallization phenomena put forward some superficial experimental results and understanding. It is confirmed that (C3.0% W> 20%) high-W cast iron crystallizes in the metastable state under the condition of casting, and the primary phase is M_6C Fe_4W_2C or Fe_3W_3C), binary eutectic M_6C + γ, ternary eutectic M_6C + γ + M_3C. Based on the experiments, the growth and crystallization of primary M_6C and the twin structure, substructure and banded structure of M_6C were proposed.