退火时间对低碳超细晶粒钢组织和性能的影响

Effect of Annealing Time on Microstructure and Properties of Low Carbon Ultrafine Grain Steel

对淬火后组织为板条马氏体的低碳钢板进行了4道次冷轧(累计相对压下量为50%),随后在550℃进行不同时间的退火处理,研究超细晶粒低碳钢的制备。结果表明,随着退火时间的延长,冷轧板条马氏体逐步发生回复、再结晶和晶粒长大,并且晶粒长大速度逐渐加快。在30 min内退火处理时,细小的纳米尺寸碳化物不断析出,钉扎再结晶晶粒晶界,有效抑制了再结晶晶粒的长大。550℃退火30 min得到平均晶粒尺寸为326 nm的超细晶粒组织,其抗拉强度为867 MPa,总伸长率为16.7%。随着退火时间进一步延长,再结晶晶粒发生长大,同时碳化物明显粗化。

The low carbon steel plate with lath martensite after quenching was subjected to cold rolling of 4 passes(the cumulative relative reduction of 50%). Then it was annealed at 550 ℃ for different time, and preparation of ultrafine grain low carbon steel was studied. The results show that with the extension of annealing time, the cold-rolled lath martensite produces the recovery, recrystallization and grain growth, and the grain growth rate accelerates gradually. When annealing treatment is within 30 min, tiny nano-scale carbides precipitate continuously, and the recrystallized grain boundaries are pinned, which effectively inhibits the growth of recrystallized grains. After annealing at 530℃ for 30 min, the ultrafine-grained microstructure with the average grain size of 326 nm is obtained. Under this condition, the tensile strength is 867 MPa, and total elongation is16.7%. With the further extension of annealing time, recrystallization grains grow up, at the same time, the carbides coarsen obviously.