EH460级船板钢的动态 CCT 曲线与组织演变

采用 Gleeble-3800热模拟试验机对EH460船板钢进行1050 ℃下变形30%和850 ℃下变形30%的双道次压缩试验。绘制了在不同冷速下连续冷却过程中钢的膨胀曲线,并在光学显微镜下观察了不同冷速下试样的室温组织。结合膨胀法与金相法,利用 Origin 8.0软件绘制了船板钢的动态 CCT 曲线。结果表明,当冷速为0.1~3 ℃/s 时,所得室温组织主要是铁素体和珠光体;当冷速大于5 ℃/s 时,出现粒状贝氏体组织,随着冷速的增加贝氏体逐渐增多,铁素体与珠光体逐渐减少;当冷速为10~15 ℃/s 时,珠光体消失,组织为铁素体与粒状贝氏体;随着冷速进一步增到 20~50 ℃/s 时不再发生铁素体相变,仅为粒状贝氏体组织。

Dynamic CCT curves and microstructure evolution of EH460 ship plate steel

Gleeble 3800-thermal simulation test machine was used to conduct double-pass compression tests on EH460 plate steel under deformation of 30% at 1050 ℃ and 30% at 850 ℃.The expansion curve of steel during continuous cooling at different cooling rates was plotted and the microstructure of the specimens at room temperature under different cooling rates was observed under optical microscope. The dynamic CCT curve of ship plate steel was plotted by Origin 8.0 software combining expansion method and metallographic method. The results show that when the cooling rate was 0.1-3 ℃/s, the obtained microstructure at room temperature was mainly ferrite and pearlite. When the cooling rate is greater than 5 ℃/s, granular bainite ppears. With the increase of cooling rate, bainite gradually increases, while ferrite and pearlite gradually decrease. When the cooling rate is 0-15 ℃/s, pearlite disappears and the microstructure was ferrite and granular bainite. With the increase of the cooling rate to 20-50 ℃/s, the ferrite phase transition does not occur, and only granular bainite can be found.