Effect of the sulfide phase on the properties of steel after heat treatment

Conclusion

For steels obtained by electroslag remelting, which are characterized by low sulfur content, it was discovered that their mechanical properties can be changed by controlling the shape and distribution of inclusions of the nonmetallic phase, viz., manganese sulfides, during heat treatment. Increased purity of steel and the attendant reduction of the size of sulfides has the result that they can dissolve during relatively low heating which is often used in production for carrying out plastic deformation.

It should be noted that when the cooling regimes are varied, there occur changes of morphology and of the distribution of inclusions almost in the entire temperatrue range of the existence of stable austenite. The values of impact toughness are directly dependent on the nature of the segregation of sulfides in heat treatment, regardless of renewed heating which is accompanied by recrystallization of the steel. Consequently, with steels obtained by electroslag remelting it is important to control not only the regimes of final treatment but also the temperature of the initial heating, the cooling rate, and also a possible delay of cooling in the austenitic range at the preliminary stage of heat treatment.