Integrating process gases effects for parts integrity investigation and surface residual stress prediction in LPBF additive manufacturing

• Grant number: 22/00616-0
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2022
• End date: November 30, 2023
• Field of knowledge: Engineering - Mechanical Engineering - Manufacturing Processes
• Mobility Program: SPRINT - Projetos de pesquisa - Mobilidade
• Principal Investigator: Erik Gustavo Del Conte
• Grantee: Erik Gustavo Del Conte
• Principal researcher abroad: Sylvain LAVERNHE
• Institution abroad: Université Paris-Saclay, France
• Host Institution: Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
• Associated research grant: 21/00553-6 - Advanced manufacturing: an investigation of the effect of process gases on the magnetic and mechanical properties of maraging 300 steel samples produced by powder bed fusion, AP.R

Abstract

Laser Powder Bed Fusion (LPBF) is a manufacturing technique layerwise performed with the action of a laser beam as the thermal source to give shape to the desired product. It is important to monitor the gas protection during this process to avoid undesirable elements and fumes that may affect the material integrity and performance. In this sense, strategies that allow real-time monitoring of the manufacturing can stimulate the industrial application of the LPBF technique due to higher predictability about the process results. Thus, the present study aims to link the production of fumes and the thermal simulation during LPBF under different gas protections and sample positioning on the build platform with the attributes of the manufactured samples, especially in terms of surface quality. Additionally, the study will investigate a thermal-based model for surface residual stress prediction, considering its criticality for typical metallic parts applications. Two materials will be considered for the study, the Inconel 718 and the maraging steel 300, regarding their relevance in the additive manufacturing area. The LPBF monitoring will be carried out with sensors that allow the obtention of images and measurement of the mechanical actions during the layerwise process. Also, a thermal simulation tool for the local temperature will assist this monitoring. From an experimental perspective, microscopy, roughness measurement, and X-Ray diffraction techniques will allow the determination of key properties of investigation: porosity, roughness, and surface residual stress, respectively. The experimental results will be correlated to signals resulting from the LBPF manufacturing to explain the main effects of positioning and different protection gases on the stability of the molten pool, parts integrity, changes in the laminar flow rate control, and surface residual stress of the products. Therefore, the study will be a promissory strategy for further understanding how the monitored parameters related to the thermal history and process atmosphere can affect the LBPF products, resulting in a model for the surface residual stress prediction. These findings can assist the efficacy boosting of the metallic additive manufacturing LPBF technique, contributing to its use in industry. (AU)