| Grain refinement is the only way to enhance both strength and impact toughness. It has become a new invest hotspot for metallurgy industry to produce fine-grain or ultra-fine grain high strength steel with a low cost by Thermo Mechanical Controlled Processing(TMCP), Compact Strip Production(CSP), ultra-fast cooling process and so on; in the meantime, grain refinement increases yield ratio of steel, that deteriorates the cold forming performance, and this also arouses the attention of domestic and foreign specialist.The present study aims at finding the effect of two-stage cooling on yield ratio of fine-crystal ferrite/perlite steel under industrial condition. All the works were taken with the original chemical composition, heating and rolling process. Effect of different cooling history on yield ratio of HP295 steel for welded gas cylinder was studied and the result implied that both fine microstructure and good mechanical properties can be attained by two-stage cooling and controlling the coiling temperature. The yield ratio of HP295 steel sheet was reduced to less than 0.8 by using two-stage cooling process. The pass percent of yield ratio was enhanced from less than 90% to more than 98% . The mechanical properties satisfied the criteria of GB6653-1994.
|
PDF Full Text Request