Abstract：Based on the hydrogen pressure theory and the state equation of gas, a calculation model of microvoid hydrogen pressure in steel under the re-heating condition was proposed, and the micro-void stress field analysis model was established. With numerical simulation, the effects of re-heating temperature, original hydrogen pressure and metal expansion on micro-void hydrogen pressure and stress field were studied. The results showed that micro-void morphology had largely affect on its surrounding stress field and decided the way of crack formation. At the hydrogen gas activation temperature ( 400 ℃) , the disappearance of the hydrogen pressure led to the mutation of the stress field. Around the micro-void, a large shear stress was generated, which was very easy to lead to secondary cracks' formation and propagation.

Keyword：hydrogen pressure model;stress field;re-heating condition;void morphology;secondary crack formation;