Ductile Fracture Micromechanisms in A508 CL3 Structural Steel

Studies of the critical void volumes ahead of cracks at the initiation of fracture at 100° C in the ductile regime show that the void volume has a maximum at a distance of about one to two crack tip opening displacements ahead of the original crack tip. The critical void volume maximum is approximately the same for prefatigue cracked notched bend bars and cusp-shaped cracks (formed by spark machining) at initiation in A508 CL3 steel. The maximum in void volume tends to have a lower value and to be closer to the crack tip for lower values of constraint stresses (that is for lower triaxiality).