Method of complex improvement of the mechanical properties of low-tempered structural steels

Abstract

1. To increase the resistance to brittle fracture of high-strength (low-tempered) structural steels, the principles of structural heredity in steels may be utilized. If a complex (serrated) shape of the grain boundaries of the austenite is produced in overheated coarse-grained steel, this increases the crack resistance as well as cold brittleness and the strength characteristics of low-tempered steel 45KhN2MFA; this indicates that the suggested kind of treatment can be used to attain a complex improvement of the characteristics of resistance to brittle fracture of this class of materials. 2. In low-alloy structural steel, the martensitic structure has fairly high resistance to brittle fracture. The unfavorably low impact toughness of these steels in the low-tempered state that is found everywhere is due to the realization of predominantly intergranular (along the boundaries of austenitic grains) crack growth upon rupture. Any method of heat treatment or change in metallurgical technology that eliminates intergranular rupture will substantially increase the resistance to brittle fracture of low-alloy high-strength structural steels.