H11Mn2SiA焊接用钢连续冷却组织转变与工艺控制

CONTINUOUS COOLING STRUCTURE TRANSFORMATION AND PROCESS CONTROL OF H11Mn2SiA WELDING STEEL

利用Gleeble-1500热模拟试验机测定了H11Mn2SiA的动态连续冷却转变(CCT)曲线,并观察了其组织和硬度。结果表明,当H11Mn2SiA从奥氏体以不同冷却速率冷却时,存在奥氏体向铁素体和珠光体的转变、贝氏体转变和马氏体转变;贝氏体转变的临界冷却速度为2.5℃/s;冷却速度达到20℃/s时会出现马氏体组织;因此H11Mn2SiA的冷却速度应控制在≤1℃/s。实践中选用终轧温度860℃～900℃、吐丝温度850±10℃和0.10～0.15 m/s的辊道速度,能够将冷却速度控制在0.3～0.6℃/s范围内,使H11Mn2SiA获得最佳的组织和性能。

Dynamic continuous cooling transformation（CCT） curves of H11Mn2SiA were measured by Gleeble-1500 thermo-mechanical simulator,then microstructure and hardness of steel were observed.The result indicated that the austenite transforming to ferrite and pearlyte,bainite and martensite were discovered when H11Mn2SiA cooled from austenite by different cooling rates;The bainite critical cooling rate was 2.5 ℃/s;Martensite would appeared when the cooling rate reached 20 ℃/s;therefore the cooling rate of H11Mn2SiA should not be more than 1 ℃/s.When the finishing temperature 860 ℃～900 ℃,the spinning temperature 850±10 ℃ and the roller speed 0.10～0.15 m/s were setted in the practice,the cooling rate of H11Mn2SiA could be controlled at 0.3～0.6 ℃/s,and it would obtain the better microstructure and properties.