Modeling residual thermal stresses in layer-by-layer formation of direct metal laser sintering process for different scanning patterns for 316L stainless steel

Hayri Sezer, Joseph Tang, AMM Nazmul Ahsan, Sudhir Kaul

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Purpose: The purpose of this study is to develop a novel comprehensive three-dimensional computational model to predict the transient thermal behavior and residual stresses resulting from the layer-by-layer deposition in the direct metal laser sintering process. Design/methodology/approach: In the proposed model, time integration is performed with an implicit scheme. The equations for heat transfer are discretized by a finite volume method with thermophysical properties of the metal powder and an updated convection coefficient at each time step. The model includes convective and radiative boundary conditions for the exposed surfaces of the part and constant temperatures for the bottom surface on the build plate. The laser source is modeled as a moving radiative heat flux along the scanning pattern, while the thermal gradients are used to calculate directional and von Mises residual thermal stresses by using a quasi-steady state assumption. Findings: In this study, four different scanning patterns are analyzed, and the transient temperature and residual thermal stress fields are evaluated from these patterns. It is found that the highest stresses occur where the laser last leaves off on its scanning pattern for each layer. Originality/value: The proposed model is designed to capture the layer-by-layer deposition for a three-dimensional geometry while considering the effect of the instantaneous melting of the powder, melt pool, dynamic calculation of thermophysical properties, ease of parametrization of various process parameters and the vectorization of the code for computational efficiency. This versatile model can be used for process parameter optimization of other laser powder bed fusion additive manufacturing techniques. Furthermore, the proposed approach can be used for analyzing different scanning patterns.

Original languageEnglish
Pages (from-to)1750-1763
Number of pages14
JournalRapid Prototyping Journal
Volume28
Issue number9
DOIs
StatePublished - Oct 14 2022

Keywords

  • Additive manufacturing
  • DMLS
  • Scanning pattern
  • Thermal gradient
  • Thermal residual stress

Fingerprint

Dive into the research topics of 'Modeling residual thermal stresses in layer-by-layer formation of direct metal laser sintering process for different scanning patterns for 316L stainless steel'. Together they form a unique fingerprint.

Cite this