工艺参数对激光熔覆层结构的影响

Effect of process parameters on structure of laser cladding layer

利用激光熔覆技术在45钢表面熔覆Ni60合金,通过正交试验研究了相关工艺参数对熔覆层结构的影响。结果表明:随电流、离焦量、激光移动间距、送粉量的增大,熔覆层的有效面积先增后降,至最佳工艺为220 A、32 mm、1.80 mm、3g/min达到峰值,分别为9.760、10.553、10.387、11.852 mm2;随电流、离焦量的增大,熔覆层的均匀性由好转差,至220 A、32mm达到最佳,而激光移动间距和送粉量的影响对其不大;经最佳工艺熔覆后的试样,熔覆层与基体之间属冶金结合,熔覆层组织为γ-Ni固溶体基体上均匀分布着铬、铁的碳化物和硼化物等硬质相,基体-热影响区-熔覆区的显微硬度从260.4HV到820.6HV呈梯度分布,熔覆层的有效面积为17.650mm2,波峰、波谷、波宽的标准差分别为0.018、0.015、0.012。

The effect of process parameters on the structure of Ni60 alloy layer coated on the surface of 45 steel by laser cladding technology was studied through orthogonal test. The results show that with the increase of current, defocusing amount, laser scanning spacing and powder feeding rate, the effective areas of cladded layer first increase, then decrease, and the maximum is achieved at 220 A, 32 mm 1.80 mm and 3 g/mn. With the increase of current and defocusing amount, the uniformity of cladded layer first becomes better, then worse. And the optimum condition is at 220 A and 32 mm. The laser scanning spacing and powder feeding rate have little effect on the uniformity of cladded layer. The bonding between cladded layer and matrix through the optimum process （current 220 A, defocusing amount 32 mm, laser mobile spacing 1.8 mm, powder feeding rate 3.0 g/min） is metallurgically bonding. The microstructures of cladded layer are consisted of γ- Ni solid solution matrix with chromium, iron carbide and boride hard phases homogeneously distributing on the matrix. The microhardness of matrix, heat affected zone and cladded layer is gradiently distributed, changing from 260.4HV to 820.6HV. The effective area of cladded layer is 17.650 mm^ and the standard deviation of wave peak, wave valley and wave width is 0.018, 0.015 and 0.012, respectively.