FTSR低碳高强钢连续冷却相变和组织细化

Continuous Cooling Transformation and Structure Refinement of A Low Carbon High Strength Steel Produced by FTSR

用Gleeble-3500热模拟机研究了低碳钢(%:0.19C、1.15Mn、0.008Mo、0.002Ti、0.032Als)85 mmFTSR(薄板坯连铸连轧)铸坯在1 000℃以5 s^(-1)速率变形40%,然后以5℃/s冷却到900℃并以50 s^(-1)的速率变形30%,再以1～70℃/s冷却到400℃,空冷的连续相转变和组织。结果表明,冷却速度≤20℃/s时连续冷却转变的组织为铁素体和珠光体;冷却速度达30℃/s时,组织中出现少量粒状贝氏体。随冷却速度增加,晶粒尺寸减小,当冷却速度达10℃/s时,钢中的晶粒尺寸≤10μm,当冷却速度≥20℃/s时,钢中晶粒细化程度减弱。

Continuous cooling transformation （CCT） and structure of 85 mm FTSR （Flexible Thin Slab rolling） cast slab of a low carbon steel （%： 0. 19C, 1.15Mn, 0. 008Mo, 0. 002Ti, 0. 032Als） deformed 40% with stain rate 5 s-1 at 1 000 ℃ then cooling with 5 ℃/s to 900 ℃ and deformed 30% with 50 s-1 and cooling to 400 ℃ with 1 -70 ℃/s, then air cooling have been studied by Gleeble-3500 thermo-mechanical simulator. Results showed that as cooling rate ≤20 ℃/s, the CCT structure of steel was ferrite and pearlite, and as cooling rate was up to 30 ℃/s, minor globular bainite occurred in structure; with increasing cooling rate the grain size decreased, and as cooling rate was up to 10 ℃/s the grain size in steel was ≤10μm and as cooling rate was≥20 ℃/s. the grain refinement extent was minor.