Influence Of Titanium Alloy Microstructure On Crack Tip Mechanical Field And Hydrogen Diffusion

Hydrogen induced cracking of titanium alloy hull components in deep sea environment is a slow crack propagation method,which brings major safety hazards to the safe service of hull components.Since titanium alloys are microscopically polycrystals composed of anisotropic grains,crystal anisotropy will produce localized stress concentration at the grain boundaries,which will affect crack propagation and hydrogen diffusion behavior.Through the combination of theoretical analysis and crystal elastic finite element simulation,a finite element model of stress-driven hydrogen diffusion is established.The effects of the field and hydrogen diffusion were investigated.The specific research contents are as follows:(1)By establishing a dual-crystal hydrogen diffusion finite element model,the effects of load and material mechanical properties on the stress field and hydrogen diffusion at grain boundaries under different crystal orientations were analyzed.By introducing cracks into the twin-crystal finite element model,the mechanical distribution law and hydrogen diffusion law of the crack tip under different conditions are analyzed,as well as the mechanical field and hydrogen diffusion at the grain crack tip under two orientations different from the initial orientation.(2)Through the regular polycrystalline finite element model and the irregular polycrystalline model based on Voronoi diagrams,the study obtained the effect of load,grain orientation,grain size and material mechanical properties on the mechanical field of polycrystalline micro structure under different polycrystalline microstructures.and hydrogen diffusion.(3)A finite element model of regular and irregular polycrystalline microstructures with cracks was established,and the effects of grain orientation,grain size,crack length and material mechanical properties on the mechanical field and hydrogen diffusion at the crack tip of the microstructure were analyzed.