Saxena Ashok, Findley Kip O
WireTough Cylinders, Bristol, VA 24201, USA.
Department of Mechanical Engineering, University of Arkansas, Fayetteville, AR 72701, USA.
Materials (Basel). 2024 Aug 30;17(17):4308. doi: 10.3390/ma17174308.
A phenomenological model for estimating the effects of load ratio and hydrogen pressure PH2 on the hydrogen-assisted fatigue crack growth rate (HA-FCGR) behavior in the transient and steady-state regimes of pressure vessel steels is described. The "transient regime" is identified with crack growth within a severely embrittled zone of intense plasticity at the crack tip. The "steady-state" behavior is associated with the crack growing into a region of comparatively lower hydrogen concentration located further away from the crack tip. The model treats the effects of and PH2 as being functionally separable. In the transient regime, the effects of the hydrogen pressure on the HA-FCGR behavior were negligible but were significant in the steady-state regime. The hydrogen concentration in the steady-state region is modeled as being dependent on the kinetics of lattice diffusion, which is sensitive to pressure. Experimental HA-FCGR data from the literature were used to validate the model. The new model was shown to be valid over a wide range of conditions that ranged between -1≤R≤0.8 and 0.02≤PH2≤103 MPa for pressure vessel steels.
本文描述了一种现象学模型，用于估计加载比和氢气压力PH2对压力容器钢在瞬态和稳态区域内氢辅助疲劳裂纹扩展速率（HA-FCGR）行为的影响。“瞬态区域”被定义为裂纹在裂纹尖端强烈塑性变形的严重脆化区内扩展。“稳态”行为与裂纹扩展到远离裂纹尖端的相对较低氢浓度区域有关。该模型将加载比和PH2的影响视为功能上可分离的。在瞬态区域，氢气压力对HA-FCGR行为的影响可忽略不计，但在稳态区域则很显著。稳态区域中的氢浓度被建模为依赖于对压力敏感的晶格扩散动力学。利用文献中的实验HA-FCGR数据对该模型进行了验证。结果表明，对于压力容器钢，新模型在-1≤R≤0.8和0.02≤PH2≤103 MPa的广泛条件范围内有效。
