Abstract: H13 tool steel powder is used as a raw material to rapidly form thin-walled structures using laser metal deposition technology. The gas/metal powder flow computational fluid dynamics (CFD) model was developed using Fluent software to analyze the forced convection heat loss parameters. The heat flow constitutive equations of the deposition process are established, the metal deposition is simulated using the life-and-death element technology, and the 3D thermo-mechanical sequential coupled finite element simulation of the laser metal deposition is performed based on the APDL language. The effects of deposition paths on the thermal distribution and residual stress field distribution of thin-walled structures were analyzed. The results show that there is a local residual tensile stress exceeding the tensile strength of the workpiece in the corners of the straight wall structure, resulting in cracks. Unlike the one-way deposition path, the zig-zag deposition path induces different symbolic residual shear stresses in the subsequent deposition layer. The temperature gradient of the one-way deposition wall is relatively low, and the residual stress is slightly lower than the zig-zag deposition wall, but the quality of the formed structures is low. The residual stress calculation results are in agreement with the experimental measurements, and can provide operation references for the deposition of specific part geometry.

Key words: H13 tool steel; laser metal deposition; heat flow constitutive equations; 3D thermo-mechanical sequential coupling finite element; residual stress field