25 - A thermal-metallurgical-mechanical analysis and hot cracking characterization of grain structure generation via laser powder bed fusion
Abstract
During the laser powder bed fusion additive manufacturing (L-PBF) process of metal materials, the columnar dendrites-based microstructure is found along the construction direction due to the high-temperature gradient. This anisotropic microstructure leads to different mechanical properties in the construction and scan directions which induce unpredictable distortion or damage for thin-walled structures during the process. The objective is to characterize the grain structure and the anisotropic mechanical behavior simultaneously during the L-PBF process. Based on the thermal-metallurgical-mechanical simulation, the hot cracking formation will be investigated. Based on the thermal-metallurgical-mechanical simulation, the hot cracking formation will be investigated. The grain morphology will be obtained by employing an existing model that combines the simulation of grain growth and the resolution of thermal and fluid mechanical modeling during the process. The Cellular Automaton (CA) method is adopted to simulate the grain growth and nucleation in the mushy zone. The thermal and hydrodynamic models have been established in a unified framework of 3D finite element / level-set (FE/LS) formulations to track the morphology of the melting pool. As for the anisotropic elasto-viscoplastic behavior, the Crystal Plasticity (CP) model, considering the slip systems of each individual grain, is adopted to obtain the simultaneous stress distribution in the grain structure based on the crystallographic results. Based on the thermal-metallurgical-mechanical simulation, the mechanisms for generating microscopic residual stresses and the defects will be studied, including the effect of the structure. Consequently, deformations at grain boundaries, intra-granular textures, inherent intergranular residual stress generated within the solidification interval, and their potential impacts on the material's mechanical response will be accessible. The implications for the development of a new hot cracking criterion will be revealed.
Speaker
Zixuan Li
Discover speaker profileMine Paris, Sophia Antipolis, France
Conference
25 - A thermal-metallurgical-mechanical analysis and hot cracking characterization of grain structure generation via laser powder bed fusion
Date/Time
20/03/2024
6:00 pm -6:20 pm
Location
Room 8