Study On Hydrogen Embrittlement Fracture Of AISI 4340 Steel Based On Peridynamic Theor

Due to its excellent comprehensive mechanical properties,high-strength steel has become the most widely used metal material in the field of engineering,and it has applications in aerospace,chemical production,and high-speed rail transportation.High-strength steel will be corroded by high temperature and high pressure,cyclic load and environmental media during service.Due to the complex influencing factors and the lack of a well-defined hydrogen embrittlement fracture mechanism,the hydrogen embrittlement fracture of materials requires long-term research.Accurately predicting the lifetime of engineered components that experience environmentally assisted cracking is a longstanding challenge in materials science.The peridynamics is an integral-type nonlocal model that allows fracture and damage to be treated as natural parts of the solution process.In this study,a coupled peridynamic hydrogen diffusion-fracture model for studying the failure of metallic materials due to hydrogen is proposed and applied to simulate hydrogen embrittlement fracture of AISI 4340 steel.Owing to the adsorption and diffusion of hydrogen along the grain boundaries of metallic materials can produce local embrittlement phenomena,the hydrogen diffusion step and the mechanical solution step are coupled when quantifying the fracture behavior resulting from the reduction in material strength due to local enrichment of hydrogen.In the coupled model,considering the effect of temperature on the diffusion coefficient of hydrogen atoms,a new peridynamic analysis method is proposed to numerically simulate and analyze the cracks caused by hydrogen embrittlement in materials.The numerical simulation results of the coupled model are highly similar to the experimental test results of hydrogen embrittlement cracking of AISI 4340 steel in 0.1 N H₂SO₄ solution in the literature,which verifies the feasibility of the model.Based on the numerical analysis modeling method of peridynamic theory and the calculation theory of coupled peridynamic hydrogen diffusion-fracture model,the simulation software for simulation analysis was developed in this research.The simulation software transforms the theoretical analysis of the material’s complex hydrogen embrittlement fracture into a simple human-computer interaction visualization platform.The software realizes the structural modeling and numerical solution of the hydrogen embrittlement fracture phenomenon of AISI 4340 steel,and visually demonstrates the entire hydrogen atom diffusion and crack propagation process.