Investigation of Performance and Residual Stress Generation of AlSi10Mg Processed by Selective Laser Melting

Lianfeng Wang,Zishan Ding,Xiaogang Zhu,Jing Sun,Biao Yan,Yihong Zhu,Xiaohui Jiang

doi:10.1155/2018/7814039

Abstract

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.

Highlights

Selective laser melting (SLM) is one of the most common ways of additive manufacturing and usually used to produce components with desired complex internal structures, and it yields shortened product development cycles [1]
Mechanical properties obtained from the tests made on samples fabricated in chessboard and uniformity scanning path under different preheating temperatures are shown in Table 3. e given values represent the mean values for three specimens. e theoretical density of the AlSi10Mg alloy forging parts is 2.68 g/cm3, the AlSi10Mg samples prepared by SLM have good compactness, the density can reach more than 97%, and the highest value is 98.88%
It suggests that the residual stresses in different directions and sizes can effectively change the properties of the materials under the combined influence of scanning strategy and preheating temperature

Summary

Introduction

Selective laser melting (SLM) is one of the most common ways of additive manufacturing and usually used to produce components with desired complex internal structures, and it yields shortened product development cycles [1]. Prashanth et al [13] evaluated the influence of different processing parameters on the room temperature tensile properties; they found that the room temperature tensile properties can be tuned insitu during the selective laser melting process giving an opportunity to define the mechanical properties of the SLM parts to suit their service requirements. Because of the high cooling rate and thermal inhomogeneity in the process of the SLM, there is a large temperature gradient between the sample and the substrate. It will have a very important influence on the solidification microstructure of metal forming parts and directly affects the macroproperties such as the crack and deformation. A systematic investigation of the extent to effects of preheating and scanning strategy on residual stress and microstructure of aluminum components has not yet fully analyzed. is works aims to systematically investigate the effects of thermal behavior during SLM of aluminum components, to explore the relationship between the residual stress and the microstructure of SLM by effectively controlling the thermal effect of the material, to achieve further optimization, and to improve the quality of the specimen during SLM

Methods

Results

Conclusion