Residual stress is a key indicator for measuring complex additive components, and its control method has received extensive attention. In this study, the finite element simulation of selective laser melting of AlSi10Mg was performed. It is found that the opposite laser scanning strategy can reduce the final residual stress of the sample. The effect of preheating the substrate to control the residual stress within a certain temperature range is obvious, and the laser scanning speed has the greatest influence on the Z-direction residual stress of the sample. The results show that the sag phenomenon is easy to occur at the laser scanning starting position, and the formed layer is the maximum residual stress region at the junction with the substrate.

During the selective laser melting (SLM) process, the scanned layers are subjected to rapid thermal cycles. By working on the mechanical properties, residual stress, and microstructure, the high‐temperature gradients can have significant effect on the proper functioning and the structural integrity of built parts. This work presents a comprehensive study on the scanning path type and preheating temperature for AlSi10Mg alloy during SLM. According to the results, SLM AlSi10Mg parts fabricated in chessboard scanning strategy have higher mechanical properties or at least comparable to the parts fabricated in uniformity scanning strategy. In the SLM processing, the residual stress in different parts of the specimen varies with temperature gradient, and the residual stress at the edge of the specimen is obviously larger than that at the center. Under the chessboard scanning and preheating temperature 160°C, the residual stress in each direction of the specimens reaches the minimum. Under different forming processes, the morphology of the microstructure is obviously different. With the increase of preheating temperature, the molten pool in the side surface is obviously elongated and highly unevenly distributed. From the coupling relationship between the residual stress and microstructure, it can be found that the microstructure of top surface is affected by residual stresses σx and σy. But the side surface is mainly governed by residual stress σy; moreover, the greater the residual stress, the more obvious the grain tilt. In the XY and XZ surfaces, the scanning strategy has little influence on the tilt angle of the grain. But, the tilt angle and morphology of the microstructure are obviously affected by the preheating temperature. The results show that the residual stresses can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature.

AlSi10Mg alloy formed by selective laser melting (SLM) has been gradually applied in aerospace and other fields, and heat treatment can further improve the properties of AlSi10Mg alloy. Therefore, it is very particularly meaningful to explore the effects of heat treatment on microstructure and residual stress of SLM AlSi10Mg alloy. An approach is proposed to evaluate the stress, strain and microstructure changes during heat treatment. As a result, the heating temperature of 350°C and tempering temperature of 200°C are the optimal heat-treatment processes. Furthermore, by tensile fracture analysis, the tensile strength of the sample after heat treatment decreases by 40%, and the total elongation after fracture increases by 280%.