激光熔覆搭接过程残余应力应变的有限元计算

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。

Finite Element Calculation of the Residual Stress and Strain of Coating during Laser Cladding Process

During laser cladding process,the residual stress and strain caused by the fast heating and cooling process make an important influence on cracks of coating.The residual stress and strain of coating during the laser cladding process are calculated by the finite element method.In the calculating process,the mainly considerations are given to the thermal stress,σ-ε curves of material,the finite element mesh of the model and the dynamics boundary conditions.The thermal stress is achieved through calculating results of the temperature field;the σ-ε curves are assumed to be that of linearity strengthened materials;and the finite element mesh adopted are divisional according to the subject investigated.With the help of finite element method,the residual stress and strain in the key points on the coating are gained respectively as 1 400 MPa and 2.2×10^-2.The results show that the cracking tendency on the crossing point of the substrate and lapped coating is largest while that on the apex of the first ring coating is the second.