金属热处理 ›› 2025, Vol. 50 ›› Issue (7): 198-203.DOI: 10.13251/j.issn.0254-6051.2025.07.028

• 材料研究 • 上一篇    下一篇

空气硬化钢的连续冷却转变曲线及力学性能

宋帅, 王立辉, 薛仁杰, 彭飞, 白丽娟, 刘丽君   

  1. 河北河钢材料技术研究院有限公司, 河北 石家庄 050000
  • 收稿日期:2025-02-10 修回日期:2025-05-23 出版日期:2025-07-25 发布日期:2025-07-28
  • 作者简介:宋帅(1994—),男,工程师,主要研究方向为汽车用钢新产品开发,E-mail:songshuai@hbisco.com
  • 基金资助:
    河北省创新能力提升计划(23561006D)

Continuous cooling transformation curve and mechanical properties of air-hardening steel

Song Shuai, Wang Lihui, Xue Renjie, Peng Fei, Bai Lijuan, Liu Lijun   

  1. Hebei HBIS Materials Technology Research Institute Co., Ltd., Shijiazhuang Hebei 050000, China
  • Received:2025-02-10 Revised:2025-05-23 Online:2025-07-25 Published:2025-07-28

摘要: 采用DIL805L相变淬火膨胀仪测试了汽车用空气硬化钢在不同冷却速度下的最终组织以及相变规律,结合硬度测量绘制了空气硬化钢的CCT曲线,并通过拉伸试验研究了退火和淬火后的力学性能。结果表明:空气硬化钢的临界温度Ac1为721 ℃,Ac3为882 ℃。当冷却速度小于0.1 ℃/s时,试验钢冷却后的最终组织为粒状贝氏体和少量的铁素体;随着冷却速率逐渐增大,铁素体含量逐渐减少,并开始产生板条贝氏体;当冷却速率达到1 ℃/s时,出现板条马氏体,并且随着冷速的增大,组织中的马氏体含量逐渐增多。拉伸测试结果表明,空气硬化钢具有良好的成形性和淬透性,奥氏体化后空冷即可硬化,得到贝氏体组织。

关键词: 空气硬化钢, CCT曲线, 显微组织, 力学性能

Abstract: Microstructure and phase transformation law of air-hardening steel under different cooling rates were tested by using a DIL805L phase transformation quenching dilatometer. Combined with hardness measurement, the CCT curve of the air-hardening steel was drawn, and the mechanical properties after annealing and quenching were studied by means of tensile test. The results show that the critical temperature Ac1 and Ac3 of the air-hardening steel is 721 ℃ and 882 ℃, respectively. When the cooling rate is less than 0.1 ℃/s, the microstructure of the steel is granular bainite and a small amount of ferrite. With the increase of cooling rate, the content of ferrite decreases gradually and lamellar bainite is produced. When the cooling rate reaches 1 ℃/s, lath martensite appeares, and with the further increase of cooling rate, the martensite content gradually increases. The tensile test results show that the air-hardening steel has good formability and hardenability, which can be hardened by air cooling after austenitizing to obtain bainite.

Key words: air-hardening steel, CCT curve, microstructure, mechanical properties

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