B、Si造渣剂对光束合金化层组织结构的影响

Influence of B,Si Slagging Elements on Microstructure of Light Beam Alloying Layer

采用B、Si造渣剂和Cr、Ni合金化粉末(Cr∶Ni=20∶80)对HT-200灰铸铁进行了光束合金化表面改性处理.实验发现,合金化层成形依赖于B、Si造渣剂对熔池金属的保护效果,合金化程度和组织均匀性则取决于B、Si造渣剂对合金化冶金过程的影响.B、Si造渣剂的加入量过少(<5mg)时,合金化层成形不良;B、Si加入量过高(>20mg)时,合金化层成分和组织均匀性下降,合金化区上部组织为γ(Fe,Ni)+(Fe,Cr)3C+α,底部组织则为γ(Fe,Ni)+莱氏体组成的亚共晶基底上分布着条块状的(Cr,Fe)7C3;而加入适量的B、Si造渣剂时,合金化层成形良好,合金化区为γ(Fe,Ni)+莱氏体组成的亚共晶组织,且组织均匀.

The surface of HT-200 grey cast iron was alloyed with B, Si slagging elements and Cr, Ni alloying powder (Cr:Ni=20:80) by light beam. The results show that the formation of alloying layer depends on the protecting effect of B, Si slagging elements on melting metal; on the other hand, the alloying degree and microstructure uniformity depend on the influence of B, Si slagging elements on alloying process. When the dosage of B, Si slagging elements is too little 20 mg), the uniformity of composition and microstructure decreases. The top of the alloying layer is composed of γ(Fe,Ni) and (Fe,Cr)3C and α, while the bottom consists of blocky (Cr,Fe)7C3 on hypoeutectic structure matrix composed of γ(Fe,Ni) and ledeburite. When the dosage of B, Si slagging elements is between the two points, the good formation and microstructure uniformity of alloying layer can be acquired. The alloying zone is hypoeutectic structure composed of γ(Fe,Ni) and ledeburite.