Fyzikální metalurgie ocelí pro kované válce

Abstract

The fracture process of rolls is a little different from the failures of rolls abroad. After the stadium of fatigue crack initiation and growth there is observed the intergranular crack growth followed by transcrystalline quasicleavage fast fracture. This reality is occurring independently to the origin of the steel production as the materials were manufactured in advanced metallurgy countries. All these results are supported by the occurrence of brittle fractures of rolls in cold rolling plants, where the fractures had the same sequence. The stage of intergranular crack growth we may connect with the existence of plate martensite in the microstructure of lath martensite, which has the detrimental effect of the damage of grain boundaries by the martensite transformation. The plate martensite may cause the premature intergranular fracture and this way also the intergranular crack growth without the presence of aggressive environment.