张永林, 安同邦, 郑庆, 等. 屈服强度1400 MPa级低合金超高强钢的SH-CCT曲线及其粗晶热影响区组织[J]. 焊接, 2023(2):24 − 28, 37. DOI: 10.12073/j.hj.20220402001
引用本文: 张永林, 安同邦, 郑庆, 等. 屈服强度1400 MPa级低合金超高强钢的SH-CCT曲线及其粗晶热影响区组织[J]. 焊接, 2023(2):24 − 28, 37. DOI: 10.12073/j.hj.20220402001
Zhang Yonglin, An Tongbang, Zheng Qing, et al. The SH-CCT diagram and CGHAZ microstructure of 1 400 MPa grade HSLA steel[J]. Welding & Joining, 2023(2):24 − 28, 37. DOI: 10.12073/j.hj.20220402001
Citation: Zhang Yonglin, An Tongbang, Zheng Qing, et al. The SH-CCT diagram and CGHAZ microstructure of 1 400 MPa grade HSLA steel[J]. Welding & Joining, 2023(2):24 − 28, 37. DOI: 10.12073/j.hj.20220402001

屈服强度1400 MPa级低合金超高强钢的SH-CCT曲线及其粗晶热影响区组织

The SH-CCT diagram and CGHAZ microstructure of 1 400 MPa grade HSLA steel

  • 摘要: 采用热模拟和显微金相、显微硬度检测等技术研究了1 400 MPa级低合金超高强钢的奥氏体化相变温度、冷却时间t8/5对其焊接热影响区粗晶区组织和性能的影响。结果表明,试验钢奥氏体化开始温度Ac1为710 ℃,奥氏体化结束温度Ac3为820 ℃;随着t8/5的增大,热影响区粗晶区的组织由全部为板条马氏体转变为粒状贝氏体+板条马氏体的混合组织,再转变为全部粒状贝氏体组织,最终转变为贝氏体 + 珠光体 + 铁素体组织;随着t8/5的增大,显微硬度从500 HV5逐渐降至250 HV5,而试验钢母材硬度值范围为502~523 HV5,因此在t8/5较大时,即在较大的焊接热输入条件下,1 400 MPa级低合金超高强钢软化现象严重,焊接过程应严格控制焊接热输入。

     

    Abstract: Austenitization temperature of the 1 400 MPa grade HSLA steel was measured by the Formastor-F Ⅱ thermal expansion measurement, and the effects of cooling time from 800 to 500 ℃ (t8/5) on the microstructure and properties of the coarse grained heat affected zone (CGHAZ) of 1 400 MPa low alloy ultra-high strength steel was investigated by using Formastor-FⅡ, optical microscope (OM), Vickers hardness tester. The experimental results indicated that the critical point Ac1 is 710 ℃ and Ac3 is 820 ℃. With the increasing of t8/5, the microstructure of CGHAZ changes from M to B + M, then to B, and finally to B + P + F. With the increasing of t8/5, the hardness gradually decreases from 500 HV5 to 250 HV5, while the hardness value of the base metal ranges from 502 HV5 to 523 HV5. Therefore, under the condition of large welding heat input, the softening phenomenon of the 1 400 MPa grade HSLA steel is serious, and the welding heat input should be strictly controlled in the welding process.

     

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