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利用Thermecmastor-Z型热模拟试验机,结合金相显微镜(OM)、扫描电镜(SEM)、维氏硬度计等,系统研究了奥氏体区变形对50CrV4钢连续冷却相变和等温相变规律的影响。建立了试验钢动态CCT曲线。研究结果表明,奥氏体变形能促进连续冷却转变过程中铁素体-珠光体、贝氏体转变,但亦可提高奥氏体的机械稳定性,进而抑制马氏体转变,Ms点由331.6℃(奥氏体未变形)降低至291℃(950℃下变形50%+890℃下变形50%,变形速率均为5s-1,变形后冷速为20℃/s)。当轧后冷速小于0.5℃/s时,试验钢中可获得铁素体+珠光体组织。此外,在研究不同变形量对试验钢等温相变规律影响时发现,650℃等温时,试验钢中发生铁素体-珠光体相变。随着变形量的增加(由30%增加至50%),其等温相变动力学加快(相变完成时间由197.6s减小至136.5s),铁素体体晶粒尺寸、珠光体片层间距减小,硬度增加。
The phase transformation and the isothermal transformation of 50CrV4 steel were systematically investigated by means of a Thermecmastor-Z thermal simulator, OM, SEM and Vickers hardness tester. Impact. The dynamic CCT curve of test steel was established. The results show that the austenite deformation can promote the transformation of ferrite - pearlite and bainite during the continuous cooling transformation, but it can also improve the mechanical stability of austenite and thus inhibit the martensitic transformation. The Ms point increases from 331.6 ℃ (Austenite without deformation) to 291 ° C (deformation at 950 ° C: 50% + deformation at 890 ° C: 50%, deformation rate: 5 s-1 and cooling rate after deformation: 20 ° C / s). When the cooling rate after rolling is less than 0.5 ℃ / s, the ferrite + pearlite structure can be obtained in the test steel. In addition, when studying the effect of different deformations on the isothermal transformation law of the test steel, it was found that the ferrite-pearlite transformation occurred in the test steel at an isothermal temperature of 650 ℃. With the increase of deformation (from 30% to 50%), the isothermal transformation kinetics accelerated (the transformation completion time decreased from 197.6s to 136.5s), the ferrite grain size, the pearlite layer spacing Reduce, increase in hardness.