After normalizing, the microstructure of SM570 steel is F+P, the grain size reaches 10, and the microstructure is S after tempering, and the content of inclusions in the steel is low, so the steel has better mechanical properties, especially the SM570 steel has better toughness at low temperature. SM570 steel hot rolled microstructure contains a small amount of bainite, after normalizing treatment, C and alloy elements are fully diffused, bainite disappeared, and because of the effect of alloy elements, the grain can be greatly refined.
The hot rolled structure of SM570 steel is F+P+B, which is because Nb and V strong carbide forming elements are added to the steel. Since their diffusion coefficients in austenite are much smaller than that of carbon, the nucleation and growth process of carbide during the perlite transition is strongly delayed, thus increasing the stability of supercooled austenite and delaying the perlite transition process.
In addition, when relatively stable carbon and nitrogen compounds are formed during the transformation process, especially trace Nb exists in the form of Nb4C3, which further hinders the diffusion of carbon and further delays the transition of pearlite, but has little influence on the transition of bainite.
BBN has developed and produced more than 3000 tons of SM570 steel, the steel is clean, the surface quality is good, all the properties meet the standard requirements, and has passed the production transfer appraisal organized by the company, has met the conditions for mass production. The hot rolling structure of SM570 steel is F+P+B(less), the normalizing structure is F+P, and the tempered structure is S cycle. SM570 steel has good low temperature toughness, and its 50%FATT is -42 ℃.
Just like you, 70% customers choose long-term cooperation with BBN steel not only for our good product and service quality, good reputation in the international market, but also for our experienced one-stop raw material supply and further steel processing!
