45钢激光硼合金化工艺优化及性能研究

Process optimization and properties of laser boron alloying on 45 steel

为提高45钢表面硬度,采用CO2激光器在45钢表面进行激光硼合金化处理,通过正交试验方法优化激光硼合金化工艺,研究合金层的组织和性能。结果表明:45钢激光硼合金化的最佳工艺参数为激光功率4 k W,扫描速度8 mm/s,KBF4的质量分数3%;经该工艺处理后的合金化层分为合金层、过渡区;合金层厚度约为860μm,组织为Fe2B及少量α-Fe,表层组织形态呈胞状,次表层呈树枝状,平均硬度为1 350HV0.1;过渡区厚度约为100μm,硬度从1 350HV0.1到230HV0.1呈梯度分布。

Laser boron alloying treatment was performed on 45 steel surface by using CO2 laser to improve the surface hardness.The process of laser boron alloying was optimized by the method of orthogonal test,and the microstructure and properties of alloyed layers were studied. The results show that the optimal process parameters for laser boron alloying of 45 steel are as follows：laser power 4 k W,scanning speed 8 mm/s and the content of KBF43%（mass fraction）. The alloyed layer is divided into two parts,alloy layer and transition zone. The thickness of the alloyed layer is about 860 μm. The microstructure of alloyed layer consists of Fe2 B and a small amount of α- Fe phase. The surface shows a cellular microstructure,while the subsurface is a dendrite structure. The average hardness of the alloyed layer is 1 350HV0.1. The thickness of transition zone is 100 μm. The hardness is gradiently reduced from 1 350HV0.1 to 230HV0.1in the transition zone.