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以厚度2 mm的低碳钢为基体材料,采用脉冲激光将厚度约为25 mm的Fe-Si-B非晶带材熔覆在低碳钢基材表层。研究脉冲功率P、脉冲宽度T、脉冲频率F、光斑直径f等工艺参数对涂层表面成形、稀释率、组织结构和显微硬度的影响。研究结果表明,当P=18.4 W,T=3.2 ms,F=3.0 Hz,f=0.3 mm时,涂层成形良好、稀释率最低、结构致密,且与基材之间呈良好的冶金结合。随着脉冲功率增大,涂层越容易发生晶化,且晶化相α、涂层、Fe2B及Fe3Si的含量和种类均增加。随着脉冲功率增大,涂层厚度增大,但涂层显微硬度下降;涂层中部显微硬度值最高,可达1400 H V,远高于低碳钢基材的100 H V。
A low-carbon steel with a thickness of 2 mm was used as the base material, and a Fe-Si-B amorphous strip with a thickness of about 25 mm was cladded on the surface of a mild steel substrate by pulsed laser. The influences of pulse power P, pulse width T, pulse frequency F and spot diameter f on the surface forming, dilution rate, microstructure and microhardness of the coating were studied. The results show that the coating is well formed with the lowest dilution rate, compact structure and good metallurgical bonding with the substrate when P = 18.4 W, T = 3.2 ms, F = 3.0 Hz and f = 0.3 mm. With the increase of pulsed power, the coating becomes more easily crystallized, and the content and types of α, coating, Fe2B and Fe3Si are increased. As the pulse power increases, the coating thickness increases, but the microhardness of the coating decreases. The microhardness of the coating reaches the highest value of 1400 HV, much higher than that of the low carbon steel substrate.