摘要
采用热模拟试验方法,测定了U75V钢轨连续冷却转变曲线和等温转变曲线,研究不同冷却速度及相变温度对组织转变及硬度的影响。通过研究冷却起始温度对钢轨性能的影响,确定了在线热处理生产开冷温度范围。结果表明：在连续冷却转变试验中,随冷却速度增大,硬度值逐渐增加,组织由珠光体逐渐向马氏体过渡,最佳冷却速度范围为1.5~4.0℃/s。在等温转变试验中,随相变温度降低,硬度逐渐升高,组织由珠光体逐渐向贝氏体过渡。不同开冷温度下显微组织均为珠光体加少量铁素体,开冷温度高于690℃时,试样硬度基本一致。建议在实际生产中,该钢种开冷温度控制在690℃以上,冷却速度控制在1.5~4.0℃/s,以保证组织及硬度满足标准要求。
Continuous cooling transformation（ CCT） and time-temperature transformation（ TTT） curves of U75 V steel rail were measured by thermal simulation,the effects of cooling rate and transition temperature on the microstructure and hardness were researched,and the start cooling temperature range of online heat treatment was determined. The results indicate that with the increase of cooling rate during continuous cooling transformation,the hardness increases,the microstructures transform gradually from pearlite to martensite,and the optimum range of cooling rate is 1. 5-4. 0 ℃/s. During isothermal transformation with the decrease of the phase-transition temperature,the hardness increases and the microstructures transform gradually from pearlite to bainite. The microstructure is pearlite and little ferrite under different start cooling temperatures. When the start cooling temperature is above 690 ℃,the hardness is basically the same. To ensure the hardness and microstructure meet the standard requirements,the start cooling temperature for this steel in practical production should be above 690 ℃,and the optimum range of cooling rate should be 1. 5-4. 0 ℃/s.
出处
《金属热处理》
CAS
CSCD
北大核心
2018年第1期152-156,共5页
Heat Treatment of Metals
基金
中国铁道科学研究院科研项目(2015YJ144)
中国铁路总公司科技研究开发计划(2015G004-A)
关键词
U75V钢轨
在线热处理
连续冷却转变
等温转变
开冷温度
U75V steel rails
online heat treatment
continuous cooling transformation
isothermal transformation
start cooling temperature
