The bake-hardening （BH） values and the ＂internal friction-temperature＂ spectrums were studied for the baked 0.11C-1.67Mn-1.19Si TRIP （transformation induced plasticity） specimens with 0%, 2% and 6% prestrain. Re...The bake-hardening （BH） values and the ＂internal friction-temperature＂ spectrums were studied for the baked 0.11C-1.67Mn-1.19Si TRIP （transformation induced plasticity） specimens with 0%, 2% and 6% prestrain. Results show that the experimental TRIP steel deserves good bake-hardening ability and Cottrell atmosphere is the reason for its bake hardening characteristic. It is also concluded that both the number and the saturation degree of Cottrell atmosphere might affect the BH value of TRIP steel.展开更多
The bake hardening （BH） behavior of transformation-induced plasticity （TRIP） and dual-phase （DP） steels after different prestrains was studied. The experimental results indicate that TRIP steel exhibits good BH ...The bake hardening （BH） behavior of transformation-induced plasticity （TRIP） and dual-phase （DP） steels after different prestrains was studied. The experimental results indicate that TRIP steel exhibits good BH ability while DP steel does not, and prestrain displays a strong effect on the BH values of both steels. The comparison of microstructures of the two steels showed that the hard second phase in the matrix might be harmful to the BH ability. For deformed specimens, baking resulted in a loss of uniform elongation, but there was no obvious decrease in uniform elongation for unprestrained specimens.展开更多
The influences of the heating rate, annealing temperature and soaking time during continuous annealing on the microstructure evolution and bake hardening behavior of the low carbon steel were investigated. After 2% pr...The influences of the heating rate, annealing temperature and soaking time during continuous annealing on the microstructure evolution and bake hardening behavior of the low carbon steel were investigated. After 2% pres- training, bake treatment （180 ℃ × 20 min） was carried out to measure BH （bake hardening） values. The results showed that, with the increase of the annealing temperature, the grain size increased except for annealing in the in- tercritical region. Furthermore, the BH value increased and the mean grain size reduced with increasing the heating rate from 5 to 80 ℃/s. The BH value was very low before complete recrystallization. After a significant decrease from 630 to 720 ℃ , the BH value enhanced when the steel was annealed at 750 ℃. With the increase of the soaking time from 20 to 100 s, the BH value reduced linearly due to the segregation of solute C atoms.展开更多
The controlled rolling and controlled cooling,bake hardening experiments have been carried out for the test steel,mechanical property test of the sample and microstructure analysis have been made by tensile testing ma...The controlled rolling and controlled cooling,bake hardening experiments have been carried out for the test steel,mechanical property test of the sample and microstructure analysis have been made by tensile testing machine,optical microscope,TEM and X-ray diffractometer.The results show that fine and uniform microstructures can achieve much higher BH and BHT values;With the increase of pre-strain there is a trend of increase first and then decrease in the BH and BHT values;bake hardening mechanism mainly consists of Cottrell atmosphere strengthening,second phase strengthening,dislocation strengthening.展开更多
文摘The bake-hardening （BH） values and the ＂internal friction-temperature＂ spectrums were studied for the baked 0.11C-1.67Mn-1.19Si TRIP （transformation induced plasticity） specimens with 0%, 2% and 6% prestrain. Results show that the experimental TRIP steel deserves good bake-hardening ability and Cottrell atmosphere is the reason for its bake hardening characteristic. It is also concluded that both the number and the saturation degree of Cottrell atmosphere might affect the BH value of TRIP steel.
文摘The bake hardening （BH） behavior of transformation-induced plasticity （TRIP） and dual-phase （DP） steels after different prestrains was studied. The experimental results indicate that TRIP steel exhibits good BH ability while DP steel does not, and prestrain displays a strong effect on the BH values of both steels. The comparison of microstructures of the two steels showed that the hard second phase in the matrix might be harmful to the BH ability. For deformed specimens, baking resulted in a loss of uniform elongation, but there was no obvious decrease in uniform elongation for unprestrained specimens.
基金Sponsored by National Natural Science Foundation of China(51174247)
文摘The influences of the heating rate, annealing temperature and soaking time during continuous annealing on the microstructure evolution and bake hardening behavior of the low carbon steel were investigated. After 2% pres- training, bake treatment （180 ℃ × 20 min） was carried out to measure BH （bake hardening） values. The results showed that, with the increase of the annealing temperature, the grain size increased except for annealing in the in- tercritical region. Furthermore, the BH value increased and the mean grain size reduced with increasing the heating rate from 5 to 80 ℃/s. The BH value was very low before complete recrystallization. After a significant decrease from 630 to 720 ℃ , the BH value enhanced when the steel was annealed at 750 ℃. With the increase of the soaking time from 20 to 100 s, the BH value reduced linearly due to the segregation of solute C atoms.
文摘The controlled rolling and controlled cooling,bake hardening experiments have been carried out for the test steel,mechanical property test of the sample and microstructure analysis have been made by tensile testing machine,optical microscope,TEM and X-ray diffractometer.The results show that fine and uniform microstructures can achieve much higher BH and BHT values;With the increase of pre-strain there is a trend of increase first and then decrease in the BH and BHT values;bake hardening mechanism mainly consists of Cottrell atmosphere strengthening,second phase strengthening,dislocation strengthening.
