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针对EQ70海洋平台用钢实际生产条件及存在问题,采用Gleeble-1500热模拟试验机测定了EQ70海洋平台用钢动态连续冷却转变膨胀曲线,再结合金相组织观察和显微硬度测定,获得EQ70海洋平台用钢动态连续冷却转变曲线。结果表明:冷速为0.05℃/s时,试验用钢的组织为粒状贝氏体以及少量的铁素体;冷速在0.1℃/s到1℃/s之间组织主要为粒状贝氏体和板条贝氏体;冷速为2℃/s时,组织为板条贝氏体和少量马氏体;随着冷速增加,马氏体的含量逐渐增多,冷速在8℃/s以上时,组织全部为马氏体。
In view of the actual production conditions and existing problems of steel for EQ70 offshore platform, the dynamic continuous cooling transformation and expansion curve of EQ70 offshore platform steel was measured by Gleeble-1500 thermal simulation test machine. Combined with the microstructure observation and microhardness measurement, the EQ70 ocean Dynamic continuous cooling platform steel transition curve. The results show that the microstructure of the test steel is granular bainite and a small amount of ferrite when the cooling rate is 0.05 ℃ / s. The microstructure of the test steel is mainly granular bainite at the cooling rate of 0.1 ℃ / s to 1 ℃ / s And lath bainite. When the cooling rate was 2 ℃ / s, the microstructure was lath bainite and a small amount of martensite. With the increase of cooling rate, the content of martensite gradually increased and the cooling rate was 8 ℃ / s Above, the organization for all martensite.