The effect of hot rolling process on microstructure evolution,mechanical properties and stress corrosion cracking(SCC)resistance of high-strength low-alloy(HSLA)steels was investigated by varying the finish rolling te...The effect of hot rolling process on microstructure evolution,mechanical properties and stress corrosion cracking(SCC)resistance of high-strength low-alloy(HSLA)steels was investigated by varying the finish rolling temperature(FRT)and total rolling reduction.The results revealed granular bainite with large equiaxed grains was obtained by a total rolling reduction of60%with the FRT of 950℃(within recrystallization temperature T_(r)).The larger grain size and much less grain boundaries should account for the relatively lower strength and SCC resistance.A larger rolling reduction of 80% under the same FRT resulted in the formation of massive martensite-austenite(M/A)constituents and resultant low ductility and SCC resistance.In contrast,a good combination of strength,ductility and SCC resistance was obtained via 80% rolling reduction with the FRT of 860℃(within non-recrystallization temperature T_(nr)),probably because of the fine grain size and M/A constituents,as well as a high density of grain boundary network.展开更多
Because of the influence of Nb-educts in cold rolled Nb-microalloy high strength steel manufactured by a continuous annealing unit, different quantities of non-recrystallized ferrite exist in the material, which leads...Because of the influence of Nb-educts in cold rolled Nb-microalloy high strength steel manufactured by a continuous annealing unit, different quantities of non-recrystallized ferrite exist in the material, which leads to great fluctuation of mechanical behavior of the material. In this study, the relationship between non-recrystallized ferrite and mechanical properties is analyzed, and some factors influencing the formation of non-recrystallized ferrite are also studied.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
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0300604)the National Nature Science Foundation of China(51801011)+1 种基金the National Materials Corrosion and Protection Data Center,the State Key Laboratory of Metal Material for Marine Equipment and Application(SKLMEA-K201908)the Fundamental Research Funds for the Central Universities(FRF-TP-18-026A1)。
文摘The effect of hot rolling process on microstructure evolution,mechanical properties and stress corrosion cracking(SCC)resistance of high-strength low-alloy(HSLA)steels was investigated by varying the finish rolling temperature(FRT)and total rolling reduction.The results revealed granular bainite with large equiaxed grains was obtained by a total rolling reduction of60%with the FRT of 950℃(within recrystallization temperature T_(r)).The larger grain size and much less grain boundaries should account for the relatively lower strength and SCC resistance.A larger rolling reduction of 80% under the same FRT resulted in the formation of massive martensite-austenite(M/A)constituents and resultant low ductility and SCC resistance.In contrast,a good combination of strength,ductility and SCC resistance was obtained via 80% rolling reduction with the FRT of 860℃(within non-recrystallization temperature T_(nr)),probably because of the fine grain size and M/A constituents,as well as a high density of grain boundary network.
文摘Because of the influence of Nb-educts in cold rolled Nb-microalloy high strength steel manufactured by a continuous annealing unit, different quantities of non-recrystallized ferrite exist in the material, which leads to great fluctuation of mechanical behavior of the material. In this study, the relationship between non-recrystallized ferrite and mechanical properties is analyzed, and some factors influencing the formation of non-recrystallized ferrite are also studied.
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.
