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本文研究了控制轧制工艺参数(奥氏体化温度、道次压下率及终轧温度)对低碳钢板轧后铁素体晶粒平均直径和脆性转化温度的影响及其相互关系。试验结果表明:轧制工艺参数中终轧温度起主要作用,决定着轧后铁素体晶粒平均直径、脆性转化温度及-40℃时的冲击韧性;在约800℃终轧,效果最好。轧后快冷时间及冷却速度对低碳钢板的组织和脆性转化温度影响的试验结果表明,延长快冷时间及加快冷却对轧后组织产生复杂影响:使魏氏组织级别增大;使伪共析珠光体量增加;使珠光体退化及细化。这样复杂的组织变化,对脆性转化温度带来复杂的影响。文中提出了低碳钢中珠光体退化的几种机制。
In this paper, the effects of controlled rolling process parameters (austenitizing temperature, pass reduction ratio and finishing temperature) on the average ferrite grain size and brittle transition temperature after mild steel rolling were studied. The results show that the final rolling temperature in the rolling process plays a major role in determining the average ferrite grain size after rolling, the brittle transition temperature and the impact toughness at -40 ℃. The final rolling at about 800 ℃ is the best . The experimental results of the influence of the fast cooling time after rolling and the cooling rate on the microstructure and brittle transition temperature of low carbon steel show that prolonging the cooling time and speeding up the cooling have a complex effect on the microstructure after rolling: Analysis of pearlite increased; pearlite degradation and refinement. Such complex organizational changes have a complex effect on the temperature of brittle transformation. Several mechanisms of degeneration of pearlite in mild steel are proposed in this paper.