Several 35CrMo4 and 38MnV7 steels with different additions of Ti and V were manufactured by electroslag remelting.The influence of the alloying and microalloying elements on phase transformation at different cooling r...Several 35CrMo4 and 38MnV7 steels with different additions of Ti and V were manufactured by electroslag remelting.The influence of the alloying and microalloying elements on phase transformation at different cooling rates was studied and the continuous cooling transformation diagrams were plotted.In order to optimize the heat treatment and improve the mechanical properties,the range of cooling rates leading to a fully bainitic microstructure(without ferrite,pearlite and especially without martensite)was determined.Bainite and martensite transformation start temperatures(B_s,M_s)were also established and compared with the values predicted by empirical equations.The important role of precipitates(especially V carbonitride particles)on final microstructure and mechanical properties was assessed.展开更多
The effect of deformation in the non-recrystallization region on the phase transformation for a low-carbon and high Nb-containing steel with coarse austenite grain size was investigated by means of dilatometric measur...The effect of deformation in the non-recrystallization region on the phase transformation for a low-carbon and high Nb-containing steel with coarse austenite grain size was investigated by means of dilatometric measurement and microstructure observation. The results show that with increasing the cooling rate, both the transformation start and finish temperatures measured by dilatometer are decreased, and the corresponding microstructure is transformed from ferrite and pearlite to full granular bainite gradually. The dynamic continuous cooling transformation diagram was plotted according to the dilatometric measurements and microstructure observations. Dilatometric measurements also show that the transformation start and finish temperatures of the test steel rise with increasing strain, strain rate and deformation temperature, and the reasons are discussed.展开更多
Continuous cooling transformation of a low carbon microalloyed steel was investigated after it was subjected to the simulation welding thermal cycle process and the interrupted cooling test.Microstructure observation ...Continuous cooling transformation of a low carbon microalloyed steel was investigated after it was subjected to the simulation welding thermal cycle process and the interrupted cooling test.Microstructure observation was performed by optical microscopy and transmission electron microscopy.On the basis of the dilatometric data and microstructure observation,the continuous cooling transformation(CCT) diagram was determined,which showed that the main microstructure changes from a mixture of lath martensite and bainitic ferrite to full granular bainite with the increase in the cooling time t_(8/5) from 10 to 600 s,accompanied with a decrease in the microhardness.The interrupted cooling test confirmed that the bainitic ferrite can form attached to grain boundaries at the beginning of transformation even if the final microstructure contains a mixture of granular bainite and bainitic ferrite.展开更多
基金the financial support of Spanish Ministry of Economy and Competitiveness through the project ref.MAT2011-29039-C02-02
文摘Several 35CrMo4 and 38MnV7 steels with different additions of Ti and V were manufactured by electroslag remelting.The influence of the alloying and microalloying elements on phase transformation at different cooling rates was studied and the continuous cooling transformation diagrams were plotted.In order to optimize the heat treatment and improve the mechanical properties,the range of cooling rates leading to a fully bainitic microstructure(without ferrite,pearlite and especially without martensite)was determined.Bainite and martensite transformation start temperatures(B_s,M_s)were also established and compared with the values predicted by empirical equations.The important role of precipitates(especially V carbonitride particles)on final microstructure and mechanical properties was assessed.
基金Item Sponsored by Applied Basic Researches Foundation of Yunnan Province of China (2009ZC004X) Educational Commission of Yunnan Province of China (09Y0051)
文摘The effect of deformation in the non-recrystallization region on the phase transformation for a low-carbon and high Nb-containing steel with coarse austenite grain size was investigated by means of dilatometric measurement and microstructure observation. The results show that with increasing the cooling rate, both the transformation start and finish temperatures measured by dilatometer are decreased, and the corresponding microstructure is transformed from ferrite and pearlite to full granular bainite gradually. The dynamic continuous cooling transformation diagram was plotted according to the dilatometric measurements and microstructure observations. Dilatometric measurements also show that the transformation start and finish temperatures of the test steel rise with increasing strain, strain rate and deformation temperature, and the reasons are discussed.
基金support of Shenyang Key Laboratory of Construction Project(Grant No. F12-256-1-00)Science Foundation for the Excellent Youth Scholars of Ministry of Education of China(Grant No. 90403006)
文摘Continuous cooling transformation of a low carbon microalloyed steel was investigated after it was subjected to the simulation welding thermal cycle process and the interrupted cooling test.Microstructure observation was performed by optical microscopy and transmission electron microscopy.On the basis of the dilatometric data and microstructure observation,the continuous cooling transformation(CCT) diagram was determined,which showed that the main microstructure changes from a mixture of lath martensite and bainitic ferrite to full granular bainite with the increase in the cooling time t_(8/5) from 10 to 600 s,accompanied with a decrease in the microhardness.The interrupted cooling test confirmed that the bainitic ferrite can form attached to grain boundaries at the beginning of transformation even if the final microstructure contains a mixture of granular bainite and bainitic ferrite.
