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| Mn含量对热轧螺纹钢连续冷却相变行为影响研究 |
| Effect of Mn content on phase transformation of hot-rolled bar steels during continuous cooling |
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| DOI： |
| 中文关键词: Mn含量 螺纹钢 动态 CCT曲线 冷却速率 显微组织 显微硬度 |
| 英文关键词: Mncontent ribbedbar dynamicCCTcurve coolingrate microstructure microhardness |
| 基金项目:产学研用企业委托项目( 90270614-KJ-002-0). |
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| 中文摘要: |
| 为明确热轧螺纹钢中 Mn含量波动对连续冷却相变行为的影响，进而优化其控轧控冷工艺，本文针对 Mn含量分别为 0.99%和 1.49%的两种钢，在 900℃的变形温度下以及 0.5~30 ℃/s冷却速率范围内，进行动态连续冷却热模拟实验。结果表明，冷却速率提升和 Mn含量增加均会抑制高温铁素体 +珠光体相变，同时促进了中温贝氏体和低温马氏体相变。相较于 Mn含量为 0.99%的钢， Mn含量为 1.49%的钢中固溶 Mn元素增多，使碳活性降低并提高了奥氏体相的稳定性，即随着钢中 Mn含量增加，高温相区明显下移，贝氏体和马氏体的临界冷却速率降低。在低冷速下， Mn含量增加提高了珠光体转变速率和体积分数；在高冷速下，随着 Mn含量增加，贝氏体和马氏体体积分数增多且马氏体相区扩大。另外，该螺纹钢硬度随冷却速率升高和 Mn含量增加而提高，对应的硬度峰值依次为 272HV0.1和 425HV0.1。 |
| 英文摘要: |
| To elucidate the effect of Mn content on the continuous cooling transformation in hot-rolled ribbed bar and to optimize the controlled rolling and cooling process，the dynamic continuous cooling thermal simulation tests were conducted on two steels with Mn contents at 0.99% and 1.49%，respectively，at a deformation temperature of 900 ℃ and within a cooling rate range of 0.5 to 30 ℃/s. The results indicate that increasing both the cooling rate and Mn content suppresses high-temperature ferrite+pearlite transformation while promoting medium-temperature bainite and low-temperature martensite transformations.Compared with the steel with 0.99% Mn content，the steel with 1.49% Mn content exhibits increased dissolved Mn，which reduces carbon activity and enhances austenite stability. Consequently，as Mn content increases，the high-temperature phase region shifts downward significantly，and the critical cooling rates for bainite and martensite are reduced. At low cooling rates，increased Mn content enhances the pearlite transformation rate and volume fraction. At higher cooling rates，increased Mn content leads to an increase in the volume fraction of bainite and martensite，along with an expansion of the martensite region.Additionally，the microhardness of the ribbed bar increases with higher cooling rate and Mn content，with peak hardness of 272HV0.1 and 425HV0.1，respectively. |
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