钴基合金激光熔覆覆层截形与显微硬度关系的调控研究

The Regulating Research of Relationship between the Section Shape of Cobalt-based Alloy’s Laser Cladding Layer and Micro-hardness

在采用钴基合金粉末对核阀密封面进行激光熔覆时,基于激光熔覆道截形常呈半月形、熔覆层由表及里存在硬度梯度以及环形熔覆道失圆和不平整的事实,提出应对熔覆带宽度,并给出合理的工艺尺寸,以保证机加工后在得到足够宽的密封面的情况下,有理想的表面硬度值与之匹配。在实验基础上建立了熔覆道截形曲率半径的数学模型、熔覆层显微硬度梯度分布的数学模型,构建了等厚度熔覆条件下以最少粉末用量为目标函数的覆层截形与显微硬度关系调控的优化设计模型,具有一定的理论和应用价值。

The laser cladding layer section often presents a half-moon shape, and there exists a hardness gradient from the outside to the inside of the layer. The annular cladding way is out of circularity and not fiat. Based on these facts above, when using cobalt-based alloy powder to conduct laser cladding on nuclear valve sealing surface, we propose to give a reasonable process dimension for the cladding way＇s width, in order to ensure that under the condition of obtaining a sufficient wide sealing surface after machining we can also get an ideal surface hardness. On the basis of experiments we established the mathematical model of cladding road section＇s curvature radius and tile mathematical model of the microhardness gradient distribution of the cladding layer. Under conditions of constant thickness of cladding layer, we also built an optimized design model which sets the minimal powder dosage as the objective function, for regulation of relationship between cladding layer section shape and its microhardness. All the models we built have a certain theoretical and practical value.