低碳高强舰船用钢的CCT曲线及其组织性能

CCT curves and microstructure and properties of low-carbon high strength marine steel

采用Gleeble-3500热模拟试验机、光学显微镜和扫描电镜等研究了低碳高强舰船用钢的连续冷却转变曲线(CCT曲线)及热轧后终冷温度对组织性能的影响。结果表明,试验钢连续冷却转变只发生了铁素体、贝氏体相变。试验钢轧后快速冷却至不同终冷温度立即空冷工艺下,室温组织主要为贝氏体和多边形铁素体,且随着终冷温度降低,贝氏体的含量增多。与直接空冷至室温相比,随着终冷温度提高,试样的强度呈先降低后增加趋势,然而,终冷温度提高到650℃时,试样强度却降低。终冷温度为600℃时,屈服强度和抗拉强度最高,分别为644.28 MPa和为679.71 MPa,-20℃的冲击吸收能量最优,为112 J。

Continuous cooling transformation curve(CCT curve)and effect of final cooling temperature after hot rolling on microstructure and properties of low-carbon high strength marine steel were studied by Gleeble-3500 thermal simulation test machine,optical microscope and scanning electron microscope.The results show that only ferrite and bainite transformations take place during the continuous cooling transformation of the tested steel.In the process of air cooling immediately after hot rolling and rapid cooling to different final cooling temperature,the room temperature microstructure is bainitic and polygonal ferrite,and the content of bainitic increases with the decrease of final cooling temperature.Compared with direct air cooling to room temperature,with the increase of final cooling temperature,the strength of the tested steel decreases at first and then increases,However,when the final cooling temperature increases to 650℃,the strength of the tested steel decreases.When the final cooling temperature is 600℃,the yield strength and tensile strength is the highest,as 644.28 MPa and 679.71 MPa respectively,and the best impact absorbed energy is 112 J at-20℃.