金属热处理 ›› 2020, Vol. 45 ›› Issue (12): 19-23.DOI: 10.13251/j.issn.0254-6051.2020.12.004

• 工艺研究 • 上一篇    下一篇

热处理工艺对过共析轨钢组织及力学性能的影响

崔健伟1, 陈林1, 赵磊城1, 邹运2   

  1. 1.内蒙古科技大学 材料与冶金学院, 内蒙古 包头 014010;
    2.内蒙古一机集团富成锻造有限责任公司 技术部, 内蒙古 包头 014032
  • 收稿日期:2020-06-15 出版日期:2020-12-25 发布日期:2021-01-14
  • 通讯作者: 陈 林,教授,E-mail:chenlin39805@163.com
  • 作者简介:崔健伟(1994—),男,硕士研究生,主要研究方向为重载轨钢组织性能控制及其疲劳行为,E-mail:1078793877@qq.com。
  • 基金资助:
    内蒙古自治区科技重大专项(zdzx2018024)

Effect of heat treatment process on microstructure and mechanical properties of a hypereutectoid steel for rail

Cui Jianwei1, Chen Lin1, Zhao Leicheng1, Zou Yun2   

  1. 1. School of Material and Metallurgy, Inner Mongolia University of Science & Technology, Baotou Inner Mongolia 014010, China;
    2. Technical Department, Inner Mongolia Firmaco Flourish Forging Co., Ltd., Baotou Inner Mongolia 014032, China
  • Received:2020-06-15 Online:2020-12-25 Published:2021-01-14

摘要: 通过显微硬度仪、冲击试验机、万能试验机和扫描电镜等研究了不同热处理工艺下某过共析轨钢组织和性能的变化规律。结果表明:热处理工艺对该轨钢的组织和力学性能较轧制态和厂方热处理态均有所优化和提高,影响因素主要为冷却速率和等温时间。随着冷却速率的提升和等温时间的减少,基体中渗碳体析出增多,珠光体尺寸减小,大片层珠光体逐渐消失;此外,试验钢的硬度、冲击吸收能量和抗拉强度均随冷速的增大呈现先增加后降低的“折线形”变化趋势,拉伸断口粗糙度增加,断裂类型从解理断裂过渡为准解理断裂。而冲击吸收能量则随着等温时间增加而增加。最佳热处理工艺为:等温温度630 ℃,等温时间30 s,冷却速率8 ℃/s,对应的最优力学性能表现为硬度402 HBW、冲击吸收能量(KV2)2.9 J、抗拉强度1312 MPa、伸长率12.24%和断面收缩率23.96%。

关键词: 热处理, 过共析轨钢, 显微组织, 力学性能, 断口形貌

Abstract: Changing laws of microstructure and properties of a hypereutectoid steel for rail under different heat treatment processes were studied by means of microhardness tester, impact testing machine, universal testing machine and scanning electron microscope. The results shows that, compared with that of the states as rolled and as factory heat treated, the microstructure and mechanical properties of the tested steel are improved by heat treatment, and the main influencing factors are cooling rate and the decrease of isothermal time. With the increase of cooling rate and the decrease of isothermal time, the precipitation of cementite in the matrix increases, the size of pearlite decreases, and the large lamellar pearlite disappears gradually. In addition, the hardness, impact absorbed energy and tensile strength increase first and then decrease with the increase of cooling rate, showing a polyline trend, the roughness of tensile fracture increases, and the fracture mode changes from cleavage to quasi cleavage, while the impact absorbed energy increases with the increase of isothermal time. Finally, the optimum heat treatment process is the isothermal temperature of 630 ℃, isothermal time of 30 s, and cooling rate of 8 ℃/s. The corresponding mechanical properties are the best, with the hardness, the impact absorbed energy, the tensile strength, the elongation and the percentage reduction of area being 402 HBW, 2.9 J, 1312 MPa, 12.24% and 23.96%, respectively.

Key words: heat treatment, hypereutectoid steel for rail, microstructure, mechanical properties, fracture morphologies

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