Nucleation of Cleavage Cracks in Crystalline Solids: Fracture at Screw-Dislocation Pile-Ups

AbstractThis paper presents two approaches to the problem of cleavage-crack nucleation by a pile-up of screw dislocations. The results obtained by a simple approximate procedure, similar in principle to that employed in a previous paper (Metal Sci. J., 1967, 1, 56) for the corresponding edge-dislocation problem, are compared with those determined by an exact approach made possible because of the special characteristics of screw dislocations. There is very good agreement between the two sets of results, indicating that the earlier results for nucleation at edge-dislocation pile-ups approximate very closely to the real state of affairs.