FRACTURE IN FORMING

The formation of cracks in metalworking processes is considered from b oth the metallurgical and mechanics points of view. Stress and strain states are shown to be important, and hydrostatic stress figures promi nently in the coalescence of voids initiated at inclusions or hard sec ond phases. Changes of stress or strain ratio during an operation can have a profound effect on cracking, as illustrated by fracture followi ng neck formation in sheet materials. Conditions for cracking in triax ial stress states will be of interest to those requiring fracture crit eria for large-deformation finite-element calculations.