摘要
为了探究1T磁场作用下600℃时不同回火时间对25CrMo48V超高强度钢碳化物演变及力学性能的影响,本文将25CrMo48V实验用钢1000℃奥氏体化30min后置于强磁场高温箱式炉中进行回火热处理,保温温度为600℃,保温时间分别为0、10、30.60、180、240min,并利用光学显微镜、扫描电子显微镜和透射电子显微镜对磁场热处理后的试样进行显微组织观察,采用维氏硬度计和电子万能试验机测试其力学性能。研究表明,未回火试样析出M3C和两种MC型碳化物,回火后试样主要有M_(3)C、M_(2)C、M_(7)C_(3)、M_(23)C_(6)。型4种碳化物析出,其演变规律为:M_(3)C→M_(2)C→M_(7)C_(3)→M_(23)C_(6)。回火30min时基体中M_(3)C几乎消失,并有M_(2)C、M_(7)C_(3)、M_(23)C_(6)析出。长时间的回火工艺会使部分M,C型碳化物转变为更稳定的M23C型碳化物,其余M_(3)C会重新溶解于回火马氏体基体中。短棒状M,C型碳化物呈链状排列,部分连成长线状M_(2)C型碳化物。回火过程中析出具有二次硬化作用的Mo_(2)C,使得试样硬度值升高。回火时间过长,则M_(7)C_(3)和M_(23)C_(6)碳化物尺寸粗化,基体内部碳含量降低,硬度值下降。
In order to investigate the effects of different tempering time at 600 C under 1T magnetic field on carbide evolution and mechanical properties of 25CrMo48V ultra-high strength steel,this study subjected the 25CrMo48V steel to austenitization at 1000℃for30min,followedby temperinginahigh-temperaturebox furnace under a strong magnetic field at 600 C.The tempering times were set at 0,10,30,60,180 and 240 min.All test steels after magnetic field heat treatment were observed for microstructure using optical microscope,scanning electron microscope and transmission electron microscope.Mechanical properties were tested using a Vickers hardness meter and electron universal testing machine.The study indicates that the as-quenched samples exhibit the precipitation of M,C and two types of MC carbides.After tempering,four types of carbidesM_(3)C、 M_(2)C、M_(7)C_(3)、M_(23)C_(6)and M_(23)C_(6)mainly precipitated from the sample,and the evolution law of these four carbides was as follows:M_(3)C→M_(2)C→M_(7)C_(3)→M_(23)C_(6).After tempering for 30 min,M,C almost completely disappeared in the sample matrix,and M_(2)C、M_(7)C_(3)、M_(23)C_(6)and M_(23)C_(6)precipitated.Prolonged tempering processes cause some M_(2)C carbides to transform into more stable M_(23)C_(6).carbides,while the remaining M_(3)C may re-dissolve into the tempered martensite matrix.The short,rod-like M_(2)C carbides are arranged in a chain-like formation,with some connecting to form elongated M,C,carbides.Due to the precipitation of Mo_(2)C with secondary hardening during the tempering process,the hardness value of the sample increases.However,excessive tempering time leads to coarsening of M,C,and M_(23)C_(6)carbides,a reduction in carbon content in the matrix,and a subsequent decrease in hardness.
作者
杨赛玄
董治中
杨晓斌
孙伟
张慧星
潘慧
董纪
YANG Saixuan;DONG Zhizhong;YANG Xiaobin;SUN Wei;ZHANG Huixing;PAN Hui;DONG Ji(School of Materials Science Engineering,Tianjin University of Technology,Tianjin 300385,China;School of Mechanical Engineering,Tianjin Sino-German University of Applied Sciences,Tianjin 300350,China;Aerospace Precision Products Inc.,Ltd.,Tianjin 300300,China)
出处
《材料科学与工艺》
北大核心
2025年第4期51-62,共12页
Materials Science and Technology
基金
天津市教委科研计划项目(2020KJ084)。
关键词
磁场热处理
25CrMo48V
超高强度钢
碳化物演变
力学性能
magnetic field heat treatment
25CrMo48V
ultra-high strength steels
carbide evolution
mechanical property
