题目：Predictions of Microstructurally Induced Failure Nucleation and Propagation in High Strength Martensitic Steel Alloys

报告人：Qifeng Wu, Ph.D.

时间：2018年1月5日上午10：00

地点：武汉大学动力与机械学院报告厅

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Abstract:

Martensitic steels, due to their high strength and toughness, are ideal material choices for critical engineering components, such as turbine blades. The high strength and toughness of martensitic steels strongly depend on their microstructures, such as the lath morphology of martensite grains, retained austenite, and carbide precipitates. The objective of this research is to investigate large inelastic deformation, microstructurally induced failure modes, and hydrogen diffusion assisted fracture in high strength martensitic steels. A dislocation-density based crystal plasticity constitutive formulation, which accounts for the martensitic microstructures and dislocation-density evolution, has been developed and coupled to a nonlinear finite element framework. Microstructure-based failure criteria and a fracture method based on overlap element method have been used to generate failure surfaces. The validated predictions indicate that the interrelated effects of the orientation and size of martensitic blocks and packets, the distribution of retained austenite and carbide precipitates can be fundamentally optimized at the microstructural scale for quasi-static, dynamic, and hydrogen diffusion assisted crack nucleation and propagation.

About the lecturer:

Dr. Qifeng Wu is a senior R&D engineer at Intel Corporation in USA, his work mainly involves in developing computational models to predict mechanical reliability of semiconductor packages. He obtained his Ph.D. in mechanical engineering from North Carolina State University in Raleigh, USA in December 2014. His research areas focus on solid mechanics, finite element analysis, crystal plasticity, constitutive modeling of crystalline metals and alloys, multiscale modeling, and electronic packaging. He obtained his bachelor degree in Naval Architecture and Ocean Engineering from Huazhong University of Science and Technology in 2009. His research work has been published at the prestigious journals, including Journal of the Mechanics and Physics of Solids, International Journal of Solids and Structures.