The effects of final rolling temperature, cooling rate and deformation on phase transition point, the duration of the phase transition and the pearlite laminar layer of non-quenched and tempered steel 45MnSiV were studied by simulating the process of rolling and post-rolling cooling on Gleeble-3500 thermal simulator and thermal expansion tester. The results show that: the ferrite and pearlite transformation temperature ranges from 510 °C to 700 °C, and the bainite transformation temperature ranges from 400 °C to 500 °C when the steel is continuously cooled at a final rolling temperature of 950 °C, and the martensite transforming temperature is 300 °C under high cooling rate (> 10 °C/s); The pearlite laminar spacing decreases with the decrease of final rolling temperature. It can be seen that the rolling deformation increases the temperature at which the test steel undergoes a phase change at each cooling rate by comparing the results of deformation and no-deformation test at 950 °C. The effect of time advance on the phase transition zone of ferrite and pearlite is particularly obvious, but the effect on the phase transition temperature and time of the bainite and martensite phase transition is not obvious. When the final rolling temperature remains constant, the Rockwell hardness value of the test steel gradually increases, and the pearlite layer spacing decreases with the decrease of ferrite transformation temperature gradually and the increase of the cooling rate.

Doping at A/B-sites can effectively improve the physical properties of perovskite ferrites. In this study, the performance of Bi0.8Ca0.2-xSrxFeO3 was investigated using the sol-gel autocombustion method. The results show that with an increase in x value, the grain size first increases and then decreases. With an increase in the doping concentration, the reunion phenomenon reduces, but the smoothness and flatness of the samples are also destroyed. Moreover, with increasing Sr 2+ concentration, particle growth is inhibited, resulting in smaller particle sizes. When the Sr 2+ concentration increases to a certain value, the environment becomes advantageous for particle growth and therefore the particle size increases. For x = 0.13, small particles are obtained. With increasing Sr 2+ concentration, the spatial modulation of the spin structure is destroyed, the lattice distorts, and the magnetic force is freed. Mössbauer spectrum measurements shows that when the Ca 2+ concentration is greater than the Sr 2+ concentration, Sr 2+ ions replace Ca 2+ ions; as a result, A-A magnetic superexchange diminishes, leading to a decrease in the hyperfine field. Appropriate doping of BiFeO3 can improve its coercivity and refine its grains and result in a larger magnetic force.