EFFECT OF HYDRIDE PRECIPITATION ON THE ELASTOPLASTIC STRESS-FIELD NEAR A CRACK-TIP

Dissolved hydrogen in zirconium diffuses up the hydrostatic stress gradient and forms hydride platelets in the region of high stress. The hydride formation is accompanied by an expansion. The effect of hydride expansion on the elastoplastic stress, strain and displacement fields, is investigated in this paper by a finite-element discretization technique. It is shown that hydride formation causes an elastic unloading in the crack tip (reduction of the peak stress) and appearance of a peak stress at the front end of the hydride. Further unloading occurs along the hydride platelet, and depending on the hydride expansion, reversed plastic deformation may take place. Effects of the hydride length, its location with respect to the crack tip, and geometry of the front end extremity of the hydride, are also investigated.