采用热膨胀法在Gleeble-3800热模拟机上测定了E690海洋平台用钢的相变临界点。同时测定了过冷奥氏体在不同冷却速度下连续转变时的膨胀曲线,绘制了其静态CCT曲线。结合金相-显微硬度法,分析了不同冷却速度对E690海洋平台用钢组织性能的影响。结果表明:冷却速度为0.05到0.5℃/s时,冷却转变的产物为粒状贝氏体;当冷速增加,达到0.1~3℃/s后,板条状贝氏体明显增多;冷却速度超过5℃/s后,冷却产物为板条贝氏体和板条马氏体。 The critical point of transformation of steel for E690 offshore platform was determined by thermal expansion method on a Gleeble-3800 thermal simulator. At the same time, the expansion curve of supercooled austenite under continuous cooling at different cooling rates was measured and the static CCT curve was drawn. The effect of cooling rate on the microstructure and properties of E690 offshore platform steel was analyzed by metallographic-microhardness method. The results show that when the cooling rate is 0.05 to 0.5 ℃ / s, the product of cooling transformation is granular bainite. When the cooling rate increases to 0.1 ~ 3 ℃ / s, the lath bainite obviously increases. The cooling rate exceeds After 5 ℃ / s, the cooling products were lath bainite and lath martensite.