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本文通过对激光表面合金成分在微观上的不均匀性的实验研究,着重从理论上探讨了产生表面合金成分在微观上不均匀的内在原因。理论分析表明:在激光辐射作用下,合金熔池内的物质迁移对流过程受到许多因素的影响和制约。这些因素包括合金元素对熔体的表面张力和粘度的影响,合金元素之间的交互作用,合金熔体的熔点变化,即温度梯度变化以及激光合金化工艺。正是上述因素改变了合金熔体的对流特征,从而成为导致表面合金成分不均匀的潜在根源。另外,在合金熔池内,对流驱动力分布的非一致性造成了合金熔体在其横截面内的对流程度和强度的非一致性,最终大大影响了表面合金的成分均匀性。最后,本文指出:通过适当的工艺控制,可以获得在微观上浓度分布均匀的表面合金。
In this paper, we study the microscopic inhomogeneity of laser surface alloy composition and focus on the theoretical analysis of the microscopic non-uniformity of the surface alloy composition. Theoretical analysis shows that under the action of laser radiation, the convection process of material migration in the molten pool is affected and restricted by many factors. These factors include the influence of alloying elements on the surface tension and viscosity of the melt, the interaction between the alloying elements, the melting point of the alloy melt, ie, the temperature gradient and the laser alloying process. It is the above factors that change the convection characteristics of the alloy melt and thus become a potential source of non-uniform surface alloy composition. In addition, the non-uniformity of the convective driving force distribution in the alloy melt pool resulted in the non-uniformity of the convection degree and the strength of the alloy melt in its cross-section, which greatly affected the compositional uniformity of the surface alloy. Finally, this paper points out: Through the appropriate process control, can be obtained in the microscopic uniform distribution of surface alloy.