On the Simulation Scalability of Predicting Residual Stress and Distortion in Selective Laser Melting

Author(s):  
C. Li ◽  
Z. Y. Liu ◽  
X. Y. Fang ◽  
Y. B. Guo

Rapid heating and cooling thermal cycle of metals in selective laser melting (SLM) generates high tensile residual stress which leads to part distortion. However, how to fast and accurately predict residual stress and the resulted part distortion remains a critical issue. It is not practical to simulate every single laser scan to build up a functional part due to the exceedingly high computational cost. Therefore, scaling up the material deposition rate via increasing heat source dimension and layer thickness would dramatically reduce the computational cost. In this study, a multiscale scalable modeling approach has been developed to enable fast prediction of part distortion and residual stress. Case studies on residual stress and distortion of the L-shaped bar and the bridge structure were presented via the deposition scalability and validation with the experimental data. High residual stress gradient in the building direction was found from high tensile on the surface to high compressive in the core. The part distortion can be predicted with reasonable accuracy when the block thickness is scaled up by 50 times the layer thickness from 30 μm to 1500 μm. The influence of laser scanning strategy on residual stress distribution and distortion magnitude of the bridges has shown that orthogonal scanning pattern between two neighboring block layers is beneficial for reducing part distortion.

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1821 ◽  
Author(s):  
Di Wang ◽  
Shibiao Wu ◽  
Yongqiang Yang ◽  
Wenhao Dou ◽  
Shishi Deng ◽  
...  

The laser scanning strategy has an important influence on the surface quality, residual stress, and deformation of the molten metal (deformation behavior). A divisional scanning strategy is an effective means used to reduce the internal stress of the selective laser melting (SLM) metal part. In order to understand and optimize the divisional scanning strategy, three divisional scanning strategies and an S-shaped orthogonal scanning strategy are used to produce 316L steel parts in this study. The influence of scanning strategy on the produced parts is verified from the aspects of densification, residual stress distribution and deformation. Experiments show that the 316L steel alloy parts adopted spiral divisional scanning strategy can not only obtain the densification of 99.37%, but they also effectively improve the distribution of residual stress and control the deformation degree of the produced parts. Among them, the spiral divisional scanning sample has the smallest residual stress in plane direction, and its σx and σy stress are controlled within 204 MPa and 103 MPa. The above results show that the spiral divisional scanning is the most conducive strategy to obtain higher residual stress performance of SLM 316L steel parts.


2019 ◽  
Vol 224 ◽  
pp. 05006
Author(s):  
Tong Ye ◽  
Xiaohui Jiang ◽  
Miaoxian Guo ◽  
Vladimir Kuptsov ◽  
Sergey Fedorov

In this paper, the selective laser melting (SLM) simulation analysis of components is carried out. The residual stress distribution of the formed part was predicted, and the influence of process parameters such as exposure time, laser power and laser scanning speed on the residual stress of the SLM formed part was analyzed. It was found that the residual stress concentration of the formed part was in the middle of the upper surface or the bottom surface. In addition, the laser power and the laser scanning speed have a great influence on the residual stress of the formed part. The results of this study lay a theoretical and experimental basis for the optimization of residual stress and quality control of SLM components.


2014 ◽  
Vol 627 ◽  
pp. 129-132 ◽  
Author(s):  
L. Parry ◽  
I. Ashcroft ◽  
D. Bracket ◽  
R.D. Wildman

Selective Laser Melting (SLM) is an Additive Manufacturing method that enables greater design freedoms than traditional manufacturing methods in the production of high value, low volume metallic parts. Despite this now being a well-established processing method, there are a number of issues impeding industrial uptake, including the generation of residual stress and part distortion during manufacture. Prediction of residual stress is invaluable for tuning process parameters, and optimising the part geometry and support structures to limit residual stress based distortion during manufacture. This paper establishes a thermal modelling strategy to predict temperature distribution within a 3D SLM part that is a precursor towards a residual stress analysis.


2019 ◽  
Vol 9 (9) ◽  
pp. 1922 ◽  
Author(s):  
Tae Woo Hwang ◽  
Young Yun Woo ◽  
Sang Wook Han ◽  
Young Hoon Moon

The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.


2021 ◽  
Vol 410 ◽  
pp. 203-208
Author(s):  
I.S. Loginova ◽  
N.A. Popov ◽  
A.N. Solonin

In this work we studied the microstructure and microhardness of standard AA2024 alloy and AA2024 alloy with the addition of 1.5% Y after pulsed laser melting (PLM) and selective laser melting (SLM). The SLM process was carried out with a 300 W power and 0.1 m/s laser scanning speed. A dispersed microstructure without the formation of crystallization cracks and low liquation of alloying elements was obtained in Y-modified AA2024 aluminum alloy. Eutectic Al3Y and Al8Cu4Y phases were detected in Y-modified AA2024 aluminum alloy. It is led to a decrease in the formation of crystallization cracks The uniform distribution of alloying elements in the yttrium-modified alloy had a positive effect on the quality of the laser melting zone (LMZ) and microhardness.


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