DEVELOPMENT OF NON-QUENCHED AND TEMPERED STEEL AND CHANGE IN ITS CHARACTERISTICS

The development of the non-quenched and tempered steel is fully summerized. A detailed investigation is made into its change in characteristics with development, ie., the chemical composition, manufacturing process, micro-structure, strenthening mechanism, properties, applications, grades and specifications. The complex micro-alloyed, cold strenthened, and bainitictype modified steels enjoy the widest and most applications, Based on the 49MnVS3 Steel, these steels are produced by lowering carbon, increasing manganese and silicon. To further improve toughness of the non-quenched and tempered steels, the warm forging, oxide metallurgy and forging residual heat quenching technologies are adopted.