FRACTURE TOUGHNESS OF THE ULTRAFINE GRAINED LOW-ALLOY STEEL AT LOW TEMPERATURE

摘要

Severe plastic deformation is a well known procedure for fabrication considerable grain refinement in metal materials. Equal channel angular pressing (ECAP) is one of these severe plastic deformation techniques which allows the receiving of the bulk ultrafine grained metals. It is well known that the ECAP method leads to significant improvement of strength of investigated materials, but the fracture mechanisms of UFG metals at low temperature are not enough studied. The investigation was performed on low-alloy constructional steel 09G2S (GOST) after application of ECAP. Fracture toughness tests were performed on Charpy impact testing specimens at low temperature. The result of the investigation is fabrication of the steel samples with stable resistance to brittle fracture at low temperature, i.e. with good cold resistance and crack resistance.