弹性连续介质中氢致裂纹传播理论

A THEORY OF HYDROGEN-INDUCED CRACK PROPAGATION IN AN ELASTIC CONTINUOUS MEDIUM

弹性连续介质中的氢原子,在裂纹应力场的诱导下发生聚集,形成氢气团,本文计算了气团分布区平均氢浓度,并将该区看作沿裂纹尖端分布的弹性夹杂,确定了夹杂的本征应变,研究了夹杂的应力场P_(ij)对裂纹位错密度的影响,求得了裂纹尖端总的应力强度因子,认为氢脆机理是氢气团增大了裂纹尖端应力强度因子,最后还讨论了氢致开裂的物理过程及氢致裂纹扩展速率,所得结果与实验符合很好。

Induced by the crack stress field, hydrogen atoms tend to gather together to form hydro-gen atmosphere in an elastic continuous medium. The average hydrogen concentration of this hydrogen atmosphere is calculated in this paper. By regarding this hydrogen atmosphere at the crack tip as an elastic inclusion, the eigen-strain of the inclusion is calculated and the influence of the stress field pij to crack dislocation density is studied. Thus the total stress intensity factor of the crack tip is obtained. We infer that the mechanism of the hydrogen embritt-lement is the enlargement of the crack stress intensity factor by this hydrogen atmosphere. The physical process of the hydrogeninduced crack propagation is also discussed. The calculated propagation rate of the crack agrees quite well with the experimental result.