控制冷却对CSP低碳锰钢组织和性能的影响

利用Gleeble 1500热模拟机测定了簿板坯连铸连轧EAF-CSP工艺生产的低碳含锰钢经奥氏体区二次变形后的CCT曲线.实验钢含有0.17%C,1.21%Mn和0.28%Si(质量分数).研究表明:提高热轧后的冷却速度使Ar_3温度降低,导致试验钢的晶粒进一步细化;冷速大于20℃/s时,出现贝氏体和铁素体的混合组织,可降低钢的屈强比;790℃终轧,550℃卷曲时出现铁素体/珠光体带状组织,提高冷速使溶质(如Mn和C)富集区在形成珠光体之前完成奥氏体—铁素体相变是避免生成铁素体/珠光体带状组织的有效方法.

Effect of Controlled Cooling on Microstructure and Mechanical Properties of CSP Low Carbon Mn-Containing Steel

By using a thermal-simulator Gleeble 1500, CCT curves of an EAF-CSP low carbon Mn-containing steel, which had been deformed in austenite region twice, were determined. The effect of accelerated cooling conditions on the microstructure and mechanical properties of the steel was studied. The steel contains 0.17% C, 1.21% Mn and 0.28% Si (mass fraction): it was found that the Ar₃ temperature is lowed by increasing the cooling rate and results in the further grain refinement. The mixture of bainite and ferrite appears while the cooling rate reaches 20 ℃/s and over. The ratio of yield to strength could be decreased by increasing the fraction of bainite. Banding structure of ferrite/pearlite exists in the steel with finishing rolling temperature 790 ℃ and coiling at 550 ℃. Accelerating the cooling rate is an effective way to avoid band structure.