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激光熔覆过程中产生的残余应力与应变对熔覆层的裂纹开裂倾向有重要影响。利用有限元法对激光多道搭接过程熔覆层的残余应力和应变进行计算,计算过程中主要考虑瞬时温度变化引起的热应力、σ-ε曲线、有限元网格、力学边界条件4个方面。热应力主要在温度场计算结果的基础上求得;σ-ε曲线采用的是线性强化材料的弹塑性曲线;有限元网格主要采用分区划分的形式进行。通过计算,得到了搭接后的熔覆层上关键点的残余应力和应变分别为1 400 MPa和2.2×10-2。结果表明:搭接熔覆层交界处的点产生焊趾裂纹的倾向最大,第1道熔覆顶点处产生横向裂纹的倾向次之。
Residual stress and strain during laser cladding have important influence on the cracking tendency of the coating. The finite element method is used to calculate the residual stress and strain of laser cladding during the lapping process. The thermal stress, σ-ε curve, finite element mesh and mechanical boundary conditions are mainly considered in the calculation process. aspect. The thermal stress is calculated mainly on the basis of the calculation results of the temperature field. The σ-ε curve is the elastic-plastic curve of the linear strengthening material. The finite element mesh is mainly divided by the zoning. Through calculation, the residual stresses and strains at the key points of the overlaminated coating are 1 400 MPa and 2.2 × 10 -2, respectively. The results show that the weld toe crack tends to be the largest at the point where the lap coating meets the junction, and the transverse crack occurs at the top of the first cladding.