Residual Stress Analysis of TC4/Inconel718 Functionally Graded Material Produced by Laser Additive Manufacturing Based on Progressive Activation Element Method

Abstract

With the continuous development of preparation technology, laser additive manufacturing (LAM) has become one of the effective ways to manufacture functionally graded materials due to its unique layer-by-layer stacking technology. However, the repeated and repeated rapid heating and cooling processes in the manufacturing process will generate large residual stress inside the structure, resulting in the destruction of the structure. In this paper, based on a new finite element method called progressive activation element method (PAE), a thermomechanical coupling model for simulating the process of LAM is established, and the influence of laser power and composition ratio of transition layers on the residual stress of the overall structure is discussed. The results show that there is a positive correlation between the laser power and the residual stress. The PAE method is compared with the traditional “Model Change” method, and it is found that the PAE method has advantages in computational efficiency, especially when calculating the residual stress of functionally graded materials, the efficiency can be improved by about 1650%. When the TC4/Inconel718 functionally graded material is prepared experimentally, the optimal composition ratio of the transition layers is 8:2. This paper provides reference for the understanding and reasonable suppression of residual stress of functionally graded materials in LAM.

Residual stress evaluation in innovative layer-level continuous functionally graded materials produced by Powder Bed Fusion-Laser Beam

“…In their investigation, Shin et al measured only surface residual stresses by X-ray diffraction in steel FGM specimens produced by DED-LB, in which the composition changed from fully ferritic to austenitic along the build direction, by exploiting 3 interlayers of 5 mm each [29]. Zhao et al have developed a numerical model for residual stress analysis of between-layer TC4-Inconel 718 FGMs [30]. However, their work did not take into account the typical process parameters of PBF-LB, which generate different residual stress elds, and in particular did not consider within-layer FGMs.…”