采用Cr,Ni单质粉末及B ,Si造渣剂以聚焦光束合金化方法在 4 5 # 钢表面合成了奥氏体型表面层。借助扫描电镜 (SEM) ,能谱仪 (EDS) ,X射线等方法研究了合金化工艺对合金化层的成型、显微组织及物相组成的影响规律。试验结果表明 ,当合金化元素加入量一定时 ,合金化层的成型及其显微组织不仅取决于热输入量 ,还与造渣元素B ,Si的加入量有关。为获得成型良好的合金化层 ,热输入量增加时必须提高造渣元素B ,Si的加入量。采用低热输入合成的合金化层的显微组织由大量的γ(Fe ,Ni)及少量的晶界α(Fe Cr)构成 ,而高热输入合成的合金化层中的γ(Fe ,Ni)晶界为γ(Fe ,Ni) +Cr2 B双相共晶 An austenitic surface layer was synthesized on the surface of steel # 4 # 5 by focused beam alloying using Cr, Ni and B and Si as slagging agents. The effect of alloying process on the forming, microstructure and phase composition of alloying layer was studied by means of SEM, EDS and X-ray. The experimental results show that the formation and microstructure of the alloying layer depends not only on the heat input, but also on the addition of slagging elements B and Si when the alloying elements are added in a certain amount. In order to obtain a well-formed alloying layer, it is necessary to increase the addition amount of slagging elements B and Si when the heat input is increased. The microstructure of the alloying layer synthesized by low heat input consists of a large amount of γ (Fe, Ni) and a small amount of grain boundary α (Fe Cr), while the γ (Fe, Ni) The boundary is γ (Fe, Ni) + Cr2 B biphasic eutectic