Effect of trace rare earth Ce element on CCT curve of high strength steel for offshore platform
In order to explore the effect of trace rare earth elements on the phase transformation behavior of high strength steel for offshore platform,the phase transformation point and continuous cooling transformation(CCT)curve of undercooled aus-tenite of FH460 steel with different rare earth Ce element content were measured by Formastor-FⅡ automatic phase transfor-mation instrument.The microstructure of FH460 steels under different cooling rates was observed and the microhardness was measured.The influence mechanism of rare earth Ce element on microstructure transformation of FH460 steel was ana-lyzed by first-principles calculation.The results show that with the increase of rare earth Ce element content,the temperature Ac3 of FH460 steel increases,the temperature Ac1 decreases,and the austenite zone is expanded.Compared with FH460 steel without Ce element,the CCT curve shape of FH460 steels with Ce element is basically unchanged,but the pearlite transformation zone and bainite transformation zone are expanded,and the Ce element inhibits the transformation of martens-ite.When the cooling rate is 30-90 ℃/h,the hardness of FH460 steel with rare earth Ce element is significantly higher than that of FH460 steel without Ce element.The addition of trace rare earth Ce element did not change the microstructure evolution of FH4 60 steel at different cooling rates.However,after adding trace rare earth Ce element,the pearlite was re-fined and the content was also significantly increased.At the same time,the transformation of bainite and the decrease of martensite lath spacing were promoted.
FH460 steel for offshore platformrare earth Ce elementcontinuous cooling transformationmicrostructure
万方数据
维普
