金属热处理 ›› 2023, Vol. 48 ›› Issue (11): 112-119.DOI: 10.13251/j.issn.0254-6051.2023.11.017

• 工艺研究 • 上一篇    下一篇

温成形高铁弹条用38Si7弹簧钢热处理后的组织性能

王天娇1, 丁小明1,2, 庄欠玉2, 蒋波3   

  1. 1.中国航发北京航空材料研究院, 北京 100095;
    2.航材国创(青岛)高铁材料研究院有限公司, 山东 青岛 266109;
    3.北京科技大学 材料科学与工程学院, 北京 100083
  • 收稿日期:2023-05-25 修回日期:2023-09-06 出版日期:2023-11-25 发布日期:2023-12-27
  • 通讯作者: 蒋 波,副教授,博士,E-mail:jiangbo@ustb.edu.cn
  • 作者简介:王天娇(1989—),女,工程师,硕士,主要研究方向为金属材料热工艺,E-mail:bdwangtianjiao@sina.com。

Microstructure and properties of warm deformed 38Si7 spring steel for high-speed rail spring bars after heat treatment

Wang Tianjiao1, Ding Xiaoming1,2, Zhuang Qianyu2, Jiang Bo3   

  1. 1. AECC Beijing lnstitute of Aeronautical Materials, Beijing 100095, China;
    2. National Innovation (Oingdao) High Speed Train Material Research Institute Co., Ltd., 0ingdao Shandong 266109, China;
    3. School of Materials Science and Engineering, University of Science and Technology Bejing, Being 100083, China
  • Received:2023-05-25 Revised:2023-09-06 Online:2023-11-25 Published:2023-12-27

摘要: 利用光学显微镜、扫描电镜、硬度计和电子万能试验机研究了温成形温度对38Si7弹簧钢变形抗力和显微组织的影响,并探讨了原始组织对淬火+回火处理后38Si7弹簧钢组织性能的影响,同时,研究了淬火+回火处理工艺参数对弹簧钢组织性能的影响。结果表明,温成形温度为720~800 ℃时,38Si7弹簧钢的变形抗力较高,为225.6~242.2 MPa。温成形温度选择800 ℃,该条件下38Si7弹簧钢的组织均匀性较好。淬火温度的控制是调控残留铁素体的含量和形貌的主要因素,淬火温度≥880 ℃,可大大减少38Si7弹簧钢中铁素体的含量。随着淬火温度的升高,38Si7弹簧钢的强度和硬度不断增大,断后伸长率呈先减小后增大的特征。淬火温度为900 ℃时,38Si7弹簧钢的综合力学性能最好,抗拉强度、硬度和断后伸长率分别为1396.8 MPa、40 HRC和12.5%,屈强比为0.9。油淬会导致网状铁素体的形成,对力学性能不利。回火温度为410~430 ℃时,回火温度的变化对试样的组织性能无明显影响,而回火温度为450 ℃时,强度和硬度明显降低,塑性提高。38Si7弹簧钢最佳的热处理工艺为900 ℃×30 min,水淬+430 ℃×60 min,空冷。

关键词: 38Si7弹簧钢, 温成形, 淬火, 回火, 组织性能

Abstract: For tested 38Si7 spring steel, the effect of warm deformation temperature on stress and microstructure, the effect of original microstructure on the microstructure and mechanical properties after quenching and tempering, and the effect of quenching and tempering parameters on the microstructure and mechanical properties were investigated, respectively, by means of optical microscope, scanning electron microscope, hardness tester and electronic universal testing machine. The results show that a higher deformation resistance is obtained when warm deformation temperature is between 720-800 ℃,which is 225.6-242.2 MPa. The temperature of warm deformation is selected as 800 ℃, at which the homogenization of microstructure of the 38Si7 spring steel is better. The main factor to control the content and morphology of retained ferrite is the quenching temperature. When the quenching temperature is higher than or equal to 880 ℃, the amount of retained ferrite in the microstructure of the 38Si7 spring steel can be greatly reduced. The strength and hardness of the steel increase with quenching temperature raising, while, its elongation decreases first and then increases. Quenched at 900 ℃, the 38Si7 spring steel has the best comprehensive mechanical properties, with tensile strength, hardness and elongation of 1396.8 MPa, 40 HRC, 12.5%, respectively, and the yield ratio is 0.9. The microstructure of network ferrite is presented when oil quenched, which is unfavorable to mechanical properties. When the tempering temperature is between 410-430 ℃, the effect of tempering temperature on microstructure and mechanical properties of the 38Si7 spring steel is slight. However, when the tempering temperature is 450 ℃, the strength and hardness are obviously reduced while the plasticity is improved. In conclusion, the optimal heat treatment process of the 38Si7 spring steel is 900 ℃×30 min, water quenching+430 ℃×60 min, air cooling.

Key words: 38Si7 spring steel, warm deformation, quenching, tempering, microstructure and properties

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