热轧65Mn带钢等温相变行为及组织性能与扁卷的协同调控
Isothermal phase transformation behavior and cooperative regulation of microstructure and properties and flat coil of hot rolling 65Mn steel strip
田亚强 1么志强 1年保国 2张俊粉 3张晓磊 3宋进英 1张明山 1陈连生1
作者信息
- 1. 华北理工大学现代冶金技术教育部重点实验室,河北唐山 063210
- 2. 河钢材料技术研究院,河北石家庄 050023
- 3. 承德钒钛新材料有限公司,河北承德 067102
- 折叠
摘要
利用淬火相变仪得到65Mn钢的等温转变曲线(TTT曲线),基于该曲线研究了不同卷取温度下钢的显微组织与力学性能的演变规律,并对扁卷产生的可能原因和调控方法进行了探讨.结果表明:获得65Mn钢典型显微组织即先共析铁素体和珠光体的温度为600～750 ℃.TTT曲线呈典型C字形,550℃为"鼻尖"温度,孕育期较短,仅有0.25 s.其中,在65Mn钢典型组织形成温度范围内,随着温度的升高,孕育期逐渐增大,并且先共析铁素体含量增多,珠光体含量降低.根据实际生产,选取的65Mn钢卷取温度为650～750℃,显微组织均为先共析铁素体和珠光体.随着卷取温度由750 ℃降低至650℃,先共析铁素体含量由19.4％减少到4.1％,分布状态逐渐由块状分布过渡到网状分布,珠光体片层间距由277.0 nm减少到178.0 nm,使65Mn钢的屈服强度由534 MPa提高到637 MPa,抗拉强度由776 MPa提高到899 MPa,硬度由18.8 HRC提高到24.3 HRC,断裂总延伸率由28.9％降低到19.4％.在实际生产中,基于TTT曲线和不同卷取温度下组织与性能的演变规律调整卷取温度与卸卷前的停留时间,可以实现组织性能与扁卷缺陷的协同调控.
Abstract
Isothermal transformation curve(111 curve)of 65Mn steel was obtained by quenching phase change machine.Based on this curve,the evolution of microstructure and mechanical properties at different coiling temperatures was studied,and the possible causes and control methods of flat coil were discussed.The results show that the typical microstructure of the 65Mn steel,namely proeutectoid ferrite and pearlite,is obtained between 600-750 ℃.The TTT curve presents a typical"C"shape,with a"nose tip"temperature of 550 ℃.The incubation period is relatively short at this temperature,only 0.25 s.Within the typical microstructure formation temperature range of the 65Mn steel,the incubation period gradually increases with the increase of temperature,and the content of proeutectoid proeutectoid ferrite increases,while the content of pearlite decreases.According to the actual production,the selected coiling temperature of the 65Mn steel is between 650-750 ℃,and the microstructure is proeutectoid ferrite and pearlite.With the coiling temperature decreases from 750 ℃ to 650 ℃,the proeutectoid ferrite content decreases from 19.4％to 4.1％,and the distribution gradually transitions from block distribution to network distribution.The pearlite lamellar spacing decreases from 277.0 nm to 178.0 nm,resulting in an increase in the yield strength of the 65Mn steel from 534 MPa to 637 MPa,an increase in ultimate tensile strength from 776 MPa to 899 MPa,an increase in hardness from 18.8 HRC to 24.3 HRC,and a decrease in percentage total extension at fracture from 28.9％to 19.4％.In actual production,the coiling temperature and the holding time before coil discharging are adjusted based on TTT curve and the evolution of microstructure and mechanical properties under different coiling temperatures can achieve synergistic regulation of microstructure,mechanical properties and flat coil defects.
关键词
65Mn钢/TTT曲线/卷取工艺/组织性能/扁卷Key words
65Mn steel/TTT curve/coiling process/microstructure and properties/flat coil引用本文复制引用
基金项目
河北省中央引导地方科技发展资金项目(246Z1021G)
出版年
2024
NETL
NSTL
万方数据