Abstract：Based on the theory of surface diffusion, a finite element method is developed to simulate shape evolutions of intragranular microcracks in metal materials due to internal pressure, stress field, electric field and thermal gradient induced surface diffusion. The results show that there is a critical value for a given aspect ratio . When , the microcrack will evolve into a cylinder directly. When , the microcrack will be divided into two right-and-left or lower-and-upper microcracks. The cylinderization time of the microcrack increases with the internal pressure increasing, while the splitting time decreases. Besides, the internal pressure is conducive to the microcrack splitting. There is a critical value of pressure for when , and are given. If , the microcrack propagation firstly appears at its lower-and-upper side with the increasing of and . The internal pressure has little influence on critical value when MPa.
2013, Vol. 34 
