摘要
为了提升高强汽车钢的安全储备能力(强塑积指标),利用扫描电子显微镜、透射电子显微镜和拉伸试验机等仪器,考察了热变形温度对汽车用低碳中锰钢微观结构、物相组成和室温拉伸性能的影响。结果表明:未再结晶区(825℃,925℃)的变形有助于在汽车钢基体中形成高位错密度并增加形核点,从而使基体组织更加细小。随着变形温度从725℃升高至1025℃,马氏体板条逐渐变宽、变短,这些弥散分布的第二相颗粒能够钉扎晶界、抑制再结晶。变形温度为725℃,825℃,925℃,1025℃时,奥氏体含量(体积分数)分别为11.43%,15.26%,15.99%,15.45%,析出相平均尺寸分别为29 nm,25 nm,19 nm,35 nm。当变形温度从725℃上升至1025℃时,汽车钢的抗拉强度呈现逐渐下降的趋势,从1254 MPa降至1198 MPa,当变形温度达到925℃及以上时,汽车钢的强塑积满足第三代汽车钢的要求(不低于30 GPa·%),适宜的热变形温度为925℃,此时强塑积最大。
In order to enhance the safety reserve capacity of high-strength plastic deposition automotive steel,the influence of hot deformation temperature on the microstructure,phase composition,and room temperature tensile properties of low-carbon medium manganese steel for automobiles was investigated.The results indicate that deformation in the unrecrystallized zone(825℃,925℃)contributes to the formation of high dislocation density and an increase in nucleation points in the automotive steel matrix,resulting in a finer matrix structure.With the increase of deformation temperature from 725℃to 1025℃,the martensitic laths gradually become wider and shorter.These dispersed second-phase particles can pin the grain boundary and inhibit recrystallization.At deformation temperatures of 725℃,825℃,925℃,1025℃,the austenite content(volume fraction)is 11.43%,15.26%,15.99%,15.45%,respectively,and the average size of precipitated phases is 29 nm,25 nm,19 nm,35 nm,respectively.When the deformation temperature rises from 725℃to 1025℃,the tensile strength of automotive steel shows a gradually decreasing trend,from 1254 MPa to 1198 MPa.When the deformation temperature reaches 925℃or above,the strength plastic product of automotive steel meets the requirements of third-generation automotive steel(not less than 30 GPa·%),and the suitable hot deformation temperature is 925℃,at which point the strength-ductility product is at its maximum.
作者
郑成
李岳强
ZHENG Cheng;LI Yueqiang(Department of Automotive Engineering,Anhui Automotive Vocational and Technical College,Hefei 230000,China;School of Materials Science and Engineering,Anhui University,Hefei 230039,China)
出处
《太原学院学报(自然科学版)》
2026年第1期75-80,共6页
Journal of TaiYuan University:Natural Science Edition
基金
安徽省自然科学重点项目(2023AH053344)。
关键词
汽车钢
热变形
变形温度
微观组织
强塑积
automotive steel
thermal deformation
deformation temperature
microstructure
strength-ductility product
