金属热处理 ›› 2022, Vol. 47 ›› Issue (9): 153-157.DOI: 10.13251/j.issn.0254-6051.2022.09.027

• 组织与性能 • 上一篇    下一篇

R350HT钢轨钢的连续冷却转变曲线

王瑞敏1,2,3, 刘曼1,2, 周剑华3, 张琪1,2, 苏雪1,2, 徐光1,2   

  1. 1.武汉科技大学 省部共建耐火材料与冶金国家重点实验室, 湖北 武汉 430081;
    2.武汉科技大学 钢铁冶金与资源利用省部共建教育部重点实验室, 湖北 武汉 430081;
    3.宝钢股份中央研究院 武汉分院, 湖北 武汉 430080
  • 收稿日期:2022-04-09 修回日期:2022-07-08 发布日期:2022-10-18
  • 通讯作者: 徐 光,教授,博士,E-mail: xuguang@wust.edu.cn
  • 作者简介:王瑞敏(1987—),男,博士研究生,主要研究方向为金属轧制等,E-mail: wangrm@baosteel.com。
  • 基金资助:
    湖北省技术创新专项重大项目(2017AAA116)

Continuous cooling transformation curve of R350HT rail steel

Wang Ruimin1,2,3, Liu Man1,2, Zhou Jianhua3, Zhang Qi1,2, Su Xue1,2, Xu Guang1,2   

  1. 1. The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan Hubei 430081, China;
    2. Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan Hubei 430081, China;
    3. Wuhan Branch, Baosteel Central Research Institute, Wuhan Hubei 430080, China
  • Received:2022-04-09 Revised:2022-07-08 Published:2022-10-18

摘要: 在Gleeble-3500热模拟试验机上对欧标R350HT钢轨钢进行不同冷却速度的热模拟试验,观察显微组织并测量硬度,绘制试验钢的连续冷却转变(CCT)曲线。结果表明,在冷却速率为0.5~2.5 ℃/s时,组织以珠光体为主,有少量先共析铁素体。当冷却速度为3 ℃/s时,组织中出现马氏体。由于珠光体轨钢中不允许有马氏体组织,因此冷却速度应小于3 ℃/s。同时,随着冷却速率的增大,直至10 ℃/s,珠光体开始转变温度降低,这是因为随着冷却速率的增大,在高温区停留时间缩短,珠光体转变来不及发生,并且发生珠光体相变需要较大的过冷度。随着冷却速率增加至20 ℃/s,组织基本上为马氏体。当冷速大于20 ℃/s后,组织为单一马氏体。因此,马氏体临界转变冷速为20 ℃/s。

关键词: R350HT钢轨钢, 连续冷却转变曲线, 热模拟, 组织

Abstract: Thermal simulation test of European standard R350HT rail steel with different cooling rates was carried out on the Gleeble-3500 thermal simulation testing machine. The microstructure was observed, the hardness was measured, and the continuous cooling transformation (CCT) curves of the tested steel was drawn. The results show that when the cooling rate is between 0.5-2.5 ℃/s, the microstructure consists of pearlite and a small amount of proeutectoid ferrite. When the cooling rate is 3 ℃/s, martensite appears in the structure. Since the pearlite rail steel should not contain martensite, the cooling rate of the tested steel should be less than 3 ℃/s. At the same time, with the increase of cooling rate until 10 ℃/s, the pearlite transformation start temperature decreases, which is because the residence time in the high temperature region is shortened with the increase of the cooling rate, and the pearlite transformation is too late to occur, and the pearlite transformation requires a large degree of undercooling. In addition, with the cooling rate increasing to 20 ℃/s, the microstructure is basically composed of martensite. When the cooling rate is greater than 20 ℃/s, the microstructure only contains martensite. Hence, the critical cooling rate of martensite transformation is 20 ℃/s.

Key words: R350HT rail steel, continuous cooling transformation curves, thermal simulation, microstructure

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