钢中氢热脱附谱线影响因素的数值模拟

Numerical simulation on influencing factors of thermal desorption spectrum of hydrogen in steel

热脱附谱线分析已广泛用于研究高强钢中氢原子的吸收与扩散行为,以及氢原子与氢陷阱之间的反应动力学参数等。通过分析热脱附谱线峰值温度可获取氢陷阱的最重要参数:氢陷阱与氢原子之间的结合能。采用McNabb-Foster模型系统模拟研究钢中氢的热脱附谱线的影响因素。结果表明:除氢原子与氢陷阱之间的结合能之外,热脱附实验加热速率以及初始实验温度,样品尺寸、形状,氢原子在氢陷阱中的初始占有率,以及在样品中的分布等均能影响热脱附谱线的峰值温度以及形状,从而对氢陷阱与氢原子之间的结合能分析产生影响。同时基于局域平衡模型的模拟结果发现热脱附过程中氢原子从低结合能氢陷阱解析后可再次被高结合能陷阱捕获。

Thermal desorption spectrum （TDS）analysis has been widely utilized to study hydrogen adsorption and diffusion in high strength steels as well as the reaction kinetic parameters between hydrogen atoms and hydrogen trap sites.The binding energy between hydrogen atoms and hydrogen trap sites,the most important parameter of the hydrogen trap sites,can be obtained by analyzing the peak temperature of the TDS.McNabb-Foster model was chosen to study the influencing factors on TDS of hydrogen in steels.The results show that besides the binding en-ergy,the shape and peak temperature of TDS can be influenced by experimental ramp rate and starting tempera-ture,specimen size and shape,initial hydrogen occupancy at the trap sites and its distribution through the speci-men,which could affect the analysis on the binding energy between hydrogen atoms and hydrogen trap sites. Meanwhile,according to the local equilibrium model,during heating process,hydrogen atoms released at the low-er binding energy trap sites could be re-trapped at the higher binding energy trap sites.