Hydrogen and micropores are widely distributed and inevitable in heavy forgings. The accumulation of hydrogen in micropores results in the formation of higher hydrogen pressure inside. In this article, the influence of heating process on hydrogen behavior around micropores is studied by finite element method. The analysis model is established theoretically and the relationship among micropore hydrogen pressure, temperature, and lattice hydrogen concentration is derived based on chemical potential balance. The results show that, during the heating process, when decomposition condition is met, hydrogen molecules begin to decompose and diffuse out of micropores. Micropore hydrogen pressure is the result of volume expansion and decomposition of micropore hydrogen molecules. Microstructures with a smaller hydrogen diffusion coefficient are more likely to form higher hydrogen pressure in micropores during heating and are more likely to form hydrogen-induced cracks. The holding temperature has little effect on micropore hydrogen pressure. Among all heat treatment parameters, the heating rate has the most significant influence on hydrogen behavior around micropores. A larger heating rate can reduce hydrogen discharge time, but increase the micropore hydrogen pressure. From the perspective of reducing micropore hydrogen pressure and heat treatment time, a heating rate of 0.05 K/s is more appropriate. This study puts forward a new mechanism of hydrogen-induced cracking in heavy forgings and provides a new perspective for formulating heat treatment processes.

氢和微孔分布广泛，在重型锻件中是不可避免的。氢在微孔中的积累导致内部形成更高的氢压力。本文通过有限元方法研究了加热过程对氢在微孔周围行为的影响。理论上建立了分析模型，并基于化学势平衡推导了微孔氢压力，温度和晶格氢浓度之间的关系。结果表明，在加热过程中，当满足分解条件时，氢分子开始分解并扩散出微孔。微孔氢压力是微孔氢分子体积膨胀和分解的结果。具有较小氢扩散系数的微结构在加热期间更可能在微孔中形成较高的氢压力，并且更有可能形成氢诱导的裂纹。保持温度对微孔氢压力几乎没有影响。在所有热处理参数中，加热速率对微孔周围氢行为的影响最大。较大的加热速率可以减少氢的排放时间，但会增加微孔氢的压力。从降低微孔氢压力和热处理时间的角度来看，更合适的是0.05 K / s的加热速率。该研究提出了重型锻件中氢致裂纹的新机理，为制定热处理工艺提供了新的思路。