ENHANCING THE MECHANICAL-PROPERTIES OF STRUCTURAL-STEELS BY RAPID HIGH-TEMPERATURE QUENCHING

Studied was the affect of austenization time in rapid high-temperature quenching on the structure and properties of 20Kh13, 30Kh13, 17Kh13G7 S and 20G7ST steels heated in a salt bath and on the kinetics of strai n-induced martensitic transformation gamma(ret) --> alpha. Optimum hea t treatment conditions from the heterophase state are proposed which e nsure the formation of a mixture of fine and cryptocrystalline martens ite and uniformly distributed retained austenite dispersed with carbid es. These structure along with the optimum kinetics of transformation of retained austenite into martensite ensure a set of enhanced mechani cal properties of steels. For example, for 30Hhl3 steel: UTS = 1620-16 80 MPa; YS0.2 = 1210-1310 MPa; elongation delta = 13-15%; reduction of area psi = 37-53%; KCU = 0.35-0.57 MJ/m(2).