热处理对激光熔覆Fe314合金涂层组织和力学性能的影响

Effects of Heat Treatment on Microstructure and Mechanical Properties of Laser Cladding Fe314 Alloy Coating

采用激光熔覆在EA4T钢上制备Fe314合金粉末熔覆层,并探究热处理温度对熔覆层组织结构和力学性能的影响。结果表明:350℃保温处理前后,熔覆层晶体形貌不发生改变;550℃保温处理后熔覆层枝晶链被打断形成棒状晶体,网状结构减少。熔覆层由奥氏体、枝晶间碳化物及CrB组成,热处理只改变晶体形貌不改变相的组成;在热处理的作用下,熔覆层和基体硬度降低且熔覆层更加接近基体的显微硬度,基体的硬度分布变得更加均匀;熔覆层和基体部分的残余应力均下降且熔覆层中拉应力转变为压应力;熔覆试样的抗冲击性能提升约1.9倍,断裂方式由脆性断裂转变为韧性断裂和脆性断裂共存的混合断裂。

Laser cladding was used to prepare Fe314 alloy powders cladding layer on EA4T steel,and the effects of heat treatment temperature on the microstructure and mechanical properties of the cladding layer were explored.The results show that the crystal morphology of the cladding layer does not change before and after the heat preservation treatment at 350℃.The dendrite chains of the cladding layer are broken after the heat preservation treatment at 550℃to form rod-shaped crystals and the network structure is reduced.The cladding layer is composed of austenite,interdendritic carbides and CrB.Heat treatment only changes the crystal morphology and does not change the phase composition.Under the action of heat treatment,the hardness of the cladding layer and the substrate decreases and the cladding layer is closer to the substrate microhardness,the hardness distribution of the matrix becomes more uniform.The residual stress of the cladding layer and the matrix part reduce,and the tensile stress in the cladding layer is transformed into compressive stress.The impact resistance of the cladding sample is increased by about 1.9 times,and the fracture mode changes from brittle fracture to a mixed fracture in which ductile fracture and brittle fracture coexist.