The Study Of45Steel Structure Evolution In The Oxide Metallurgy Process Under Pulsed Magnetic Field

The change of the steel sample in the high temperature phase change process canbe continuously observed and recorded by means of high temperature laser confocalmicroscope and it can be accurately controlled in the process of temperature changing.By using of high temperature laser confocal microscope equipped with independentlydeveloped pulse magnetic field generator, this paper aims to investigate the influencesof pulse magnetic field on solidification behavior of45steel, on the solidified structureof steel, on the behavior of inclusions in steel and regularity of inducing intracrystallineferrite.Pulsed magnetic field has a great influence on the solidification process of45steel.By controlling the reasonable parameters of pulse magnetic field, it can refine thesolidification organization, and control the distribution of inclusions and inducednuclear intracrystalline iron element shape so as to improve the comprehensiveperformance of45steel. The details are as follows:1) It has obvious effect on the solidification process of liquid steel by applyingpulse magnetic field. The temperature difference in the solidification process can beslightly shortened. The dendrite is bulky and the size is uneven in the solidificationprocess of untreated samples. By the treatment of pulse magnetic field.2) The change of the pulse magnetic field cycle, intensity and duration has certaininfluence on refining the structure of steel. The pulse magnetic field cycle of2.0s, thebetter refining results; the greater pulse magnetic field intensity reduced by the pulsemagnetic field voltage, the better refining effect. By changing the cooling rate odsolidification process, the time of the magnetic field acting on the solidification processcan be changed. By both the influence of cooling rate and pulse magnetic field onsolidification organizations, the change of grain size is more complicated. Therefinement of grain is best when the magnetic field voltage is100v and the cooling rateis about50℃/min.3) The change of the pulse magnetic field cycle, intensity and duration has directinfluence on the behavior of the inclusions in steel during solidification process. Withthe greater pulse magnetic field intensity reduced by the pulse magnetic field voltage,The distribution of inclusions becomes smaller and more dispersive. When the cycle ofpulse magnetic field is smaller, the inclusions distributing is more uniform and the sizealso magnetic field is smaller, the inclusions distribution is more uniform and the sizealso gradually decreased. By changing the action time of the magnetic field, when themagnetic field voltage is100v and the cooling rate is about100℃/min, the distributioneffect of inclusions is the best.4) By the analysis of the size and number of inclusions-induce intragranular ferritenucleation, the influence of pulse magnetic field on the class of inclusions inducingintracrystslline ferrite is not obvious. This is mainly because the compositeTi-N-V-Mn-S. And MnS and the size of inclusions is within2microns. With the increase ofmagnetic field cycle the number of the induced ferrite decreases. When the voltage is100v, the cooling rate is100℃/min, the number of the induced ferrite is the most andthe size is the smallest.