Description

This paper investigates behavior of bolts’ defects (cracks) of varying magnitude that may occur in bolt production processes (compression, upsetting). The objective has been to determine whether surface micro-cracks in the bolt semi-products can be a source of macro-cracks that might occur during the further processing stages leading to a serious damage of the material utilised. Principal attention was paid to determining of the extreme limit deformation as a result of the upsetting and compression stages ofthe bolt semiproduct forming; at which point propagation of cracks – causing the material brittleness – may start. Note that it concerns production of high-strength bolts for automobile industries that demand extreme strength and finest surface qualities of components utilized.