Effect of C Content on Microstructure and Mechanical Properties

Through intermediate frequency induction furnace smelting and argon blowing refining, Si-Mn series low alloy cast steel samples with low sulfur and phosphorus were prepared. The samples were heat treated by normalizing + quenching + low temperature tempering process, and their hardness and impact toughness were tested. The microstructure and fracture morphology of the samples were observed by OM and SEM. The research results show that when the carbon content is 0.33%, the Rockwell hardness is HRC 48, the impact value AKV is 38 J/cm2, the comprehensive mechanical properties of the alloy are the best, and its microstructure is mainly lath martensite and retained austenite. , and a small amount of bainite. With the increase of carbon content, the amount of retained austenite decreases, acicular martensite and carbides increase, the hardness of the alloy increases, but the impact toughness decreases significantly