RUPTURE STRENGTH OF STRUCTURAL-STEELS AFTER THERMOMECHANICAL TREATMENT

1. A significant improvement in the set of in-service properties of the commercially smelted ferritic-pearlitic steels under investigation is achieved as a result of TMT in the intercritical temperature interval (regulated rolling at 800°C) and accelerated cooling; this is associated with the formation of mixed ferritic-martensitic and ferritic-bainitic-martensitic structures, which ensure a simultaneous improvement in strength, plasticity, impact strength, cold resistance, and crack resistance (fracture toughness). 2. Even a negligible change in the alloying system of monotypic ferritic-pearlitic structural steels (an increase in carbon content from 0.15 to 0.18% and alloying with 0.2% of Mo in lieu of 0.33% of Cu) leads to a significant change in the character of the fine crystalline structure during TMT in the intercritical temperature interval, and, consequently, to a different degree of hardening and resistance to brittle fracture for this class of steels. © 1991 Plenum Publishing Corporation.