金属热处理 ›› 2023, Vol. 48 ›› Issue (10): 143-150.DOI: 10.13251/j.issn.0254-6051.2023.10.021

• 工艺研究 • 上一篇    下一篇

回火温度对1100 MPa高强海工钢组织及析出的影响

赵宋1, 亚斌1, 罗小兵2, 张兴国1   

  1. 1.大连理工大学 材料科学与工程学院, 辽宁 大连 116023;
    2.钢铁研究总院有限公司 工程用钢院, 北京 100081
  • 收稿日期:2023-03-07 修回日期:2023-07-29 出版日期:2023-10-25 发布日期:2023-12-07
  • 通讯作者: 罗小兵,高级工程师,E-mail:luosir2007@sina.com
  • 作者简介:赵 宋(1992—),男,硕士研究生,主要研究方向为超高强海工钢,E-mail:767437631@qq.com。

Effect of tempering temperature on microstructure and precipitation of a 1100 MPa high strength marine engineering steel

Zhao Song1, Ya Bin1, Luo Xiaobing2, Zhang Xingguo1   

  1. 1. School of Materials Science and Engineering, Dalian University of Technology, Dalian Liaoning 116023, China;
    2. Research Institute of Structural Steels, Central Iron and Steel Research Institute Co., Ltd., Beijing 100081, China
  • Received:2023-03-07 Revised:2023-07-29 Online:2023-10-25 Published:2023-12-07

摘要: 采用OM、EBSD和TEM等分析方法对超高强含Cu海工钢经850 ℃淬火+不同温度回火处理后组织和力学性能进行了研究。结果表明,试验钢在425 ℃回火时出现硬度峰值435 HV5,这是基体中细小弥散分布的Cu(5 nm)粒子和少量的碳化物粒子的协同强化作用。在525 ℃过回火状态下,试验钢基体中Cu粒子发生粗化(6.5 nm),试验钢的强度下降,并且此时试验钢中脆化相M3C渗碳体完全溶解转化为了更稳定的M2C析出相、大角度晶界密度的增加和薄膜状逆转变奥氏体的含量增加等因素,使得-40 ℃时的冲击吸收能量KV2从475 ℃回火的6 J提升至525 ℃回火的180 J,低温韧性得到了显著改善。随着回火温度的再次升高,马氏体基体软化更为明显,且 Cu粒子和M2C碳化物进一步粗化,试验钢的强度明显降低。试验钢在525 ℃回火能获得良好的强韧性匹配,抗拉强度和屈服强度分别为 1188 MPa 和 1119 MPa,-40 ℃时的冲击吸收能量KV2为 180 J。

关键词: 海工钢, 回火温度, 回火脆性, Cu析出强化

Abstract: Microstructure and mechanical properties of an ultra-high strength Cu-bearing marine engineering steel quenched at 850 ℃ and tempered at different temperatures were studied by means of OM, EBSD and TEM. The results show that when the tested steel is tempered at 425 ℃, a hardness peak of 435 HV5 appears, which is the synergistic strengthening effect of finely dispersed 5 nm Cu particles and a small amount of carbide particles in the matrix. In the overtempering state of 525 ℃, the Cu particles in the tested steel matrix are coarsened (6.5 nm), the strength of the tested steel decreases, and factors such as that the brittle phase M3C cementite in the tested steel is completely dissolved and transforms into more stable M2C precipitates, and the increase of the density of high-angle grain boundaries, as well as the content of film-like reverse-transformed austenite make the KV2 at -40 ℃ increase from 6 J tempered at 475 ℃ to 180 J tempered at 525 ℃, thus the low temperature toughness is significantly improved. As the tempering temperature increases again, the softening of the martensite matrix is more obvious, and the Cu particles and M2C carbides are further coarsened, and the strength of the tested steel is significantly reduced. It is concluded that the properties of the tested steel tempered at 525 ℃ achieves a good match of strength and toughness, the tensile strength and yield strength are 1188 MPa and 1119 MPa, respectively, and the impact absorbed energy KV2 at -40 ℃ is 180 J.

Key words: marine engineering steel, tempering temperature, temper brittleness, Cu precipitation strengthening

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