Effect of supporting structure design on residual stresses in selective laser melting of AlSi10Mg

Jiang Xiaohui,Guo Honglan,Yu Chunbo,Gao Shan,Zhang Yong

doi:10.1007/s00170-021-08010-5

Abstract

Residual stress is a key indicator to measure the forming quality of selective laser melting (SLM) components, and its control method has received extensive attention. As an auxiliary structure for forming SLM components, the structural characteristics of the supporting structure will affect the residual stress distribution of the formed parts. Therefore, it is extremely meaningful to explore the influence of the supporting structure design on the residual stress of SLM AlSi10Mg alloy. In this study, an approach is proposed to select and design the supporting structure for forming SLM components with different structural characteristics to achieve the purpose of reducing the residual stress in the overhanging structure of the components. As the result shows, when the contact area of single supporting tooth structure and component overhanging structure is 0.25mm2 and the X/Y interval of main supporting structure is 2.5mm, the forming effect is relatively good. Furthermore, the block supporting structure is more suitable for the overhanging structure which has small areas and less height, and the contour support is more suitable for the overhanging structure with larger area.

Highlights

Selective laser melting (SLM) part after solidification and cooling. [6,7] Residual stresses in components may lead to warping, cracking and reducing mechanical strength of the part, the analysis of residual stresses in SLM is a necessary aspect to ensure reliable part quality, it is influenced by SLM process parameters and supporting structure, etc. [8,9] select suitable SLM parameters and design special supporting structures to reduce the residual stresses in metal parts to improve the surface quality and forming efficiency of the parts
The design of the supporting structure is of great importance for SLM components
A is proposed based on a combination of numerical simulations and conventional experiments for the analysis of residual stress in components with overhanging structures

Summary

Introduction

As an emerging manufacturing technology, additive manufacturing (AM) technology has great developing potential in the global manufacturing industry, which has gained wide concentration. [1,2,3] Selective laser melting (SLM) is a typical additive manufacturing technology, the technology uses a laser heat source to melt metal powder to form a cladding layer and solidify it by heat dissipation into a high-performance metal part with a complex threedimensional structure. [4] Selective laser melted component has good mechanical properties such as strength of extension, elongation, Young’s modulus, impact toughness and hardness. [5] SLM technology has many great advantages in precise parts of complex form, the unbalanced temperature distribution and the inability to exert local thermal effects result in high residual stress inside the SLM part due to the concentrated energy and high power of the laser, resulting in uneven expansion and contraction of the material on the powder bed, and high residual stresses inside the SLM part after solidification and cooling. [6,7] Residual stresses in components may lead to warping, cracking and reducing mechanical strength of the part, the analysis of residual stresses in SLM is a necessary aspect to ensure reliable part quality, it is influenced by SLM process parameters and supporting structure, etc. [8,9] select suitable SLM parameters and design special supporting structures to reduce the residual stresses in metal parts to improve the surface quality and forming efficiency of the parts.On the basis studies of the SLM process parameters on residual stress, many scholars have developed thermodynamic models from the SLM process perspective and explored the effects of process parameters such as laser heat source, powder thickness and scanning speed, with the aim of improving the performance of SLM alloys. [10,11,12] In the early days, some researchers used finite element simulations to calculate the temperature field distribution near the laser spot in the SLM process and pointed out that a large temperature gradient would have a negative effect, but did not calculate the stress field. [13] Based on the thermo-elasticity theory, a thermo-dynamic coupling model was established in the SLM process, and the thermal and residual stress in the heat-affected zone was calculated. [14] Yadroitsev I et al [15] studied the residual stresses in stainless steel 316 L and Ti6Al4V alloy parts using numerical simulations and X-ray diffraction techniques. [8,9] select suitable SLM parameters and design special supporting structures to reduce the residual stresses in metal parts to improve the surface quality and forming efficiency of the parts. On the basis studies of the SLM process parameters on residual stress, many scholars have developed thermodynamic models from the SLM process perspective and explored the effects of process parameters such as laser heat source, powder thickness and scanning speed, with the aim of improving the performance of SLM alloys. On the basis studies of the supporting structures on residual stress, many scholars have considered the forming angle of supporting structure and the direction of the component with the reduction of the supporting structures, aiming to improve the performance of SLM alloy and forming efficiency. Geometric design and optimization of the supporting structure can improve the quality and efficiency of SLM formed parts

Methods

Results

Conclusion