Abstract

The effect of austempering time after the bainitic transformation on the microstructure and property in a low-carbon bainite steel was investigated by metallography and dilatometry. The results showed that by prolonging the austempering time after the bainite transformation, the amount of large-size martensite/austenite islands decreased, but no significant change of the amount and morphology of bainite were observed. In addition, more austenite with a high carbon content was retained by prolonging the holding time at the bainite transformation temperature. Moreover, with a longer holding time, the elongation was improved at the expense of a small decrease in tensile strength. Finally, the Avrami equation B_RF = 1− exp(−0.0499 × t^0.7616) for bainite reaction at 350°C was obtained for the tested steel. The work provided a reference for tailoring the properties of low-carbon steels.

中文翻译：

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等温时间对低碳贝氏体钢组织和性能的影响

摘要

贝氏体转变后的回火时间对低碳贝氏体钢组织和性能的影响通过金相和膨胀法进行了研究。结果表明，通过延长贝氏体转变后的回火时间，大尺寸马氏体/奥氏体岛的数量减少，但未观察到贝氏体数量和形貌的显着变化。另外，通过延长在贝氏体转变温度下的保持时间，可以保留更多具有高碳含量的奥氏体。此外，在保持时间较长的情况下，以拉伸强度的小幅下降为代价提高了伸长率。最后，Avrami方程B _RF = 1-exp（-0.0499× t ^0.7616对于被测钢，获得了在350℃下的贝氏体反应。这项工作为调整低碳钢的性能提供了参考。