The hot deformation behavior and microstructure evolution of industrial grade American Iron and Steel Institute(AISI)M35 high-speed steel produced by electroslag remelting at different parameters were investigated.The...The hot deformation behavior and microstructure evolution of industrial grade American Iron and Steel Institute(AISI)M35 high-speed steel produced by electroslag remelting at different parameters were investigated.The results indicated that grains coarsening and M2C carbides decomposing appeared in the steel at 1150℃for 5 min,and the network carbides were broken and deformed radially after the hot deformation.A constitutive equation was determined based on the corrected flow stress-strain curves considering the effects of friction and temperature,and a constitutive model with strain-compensated was established.The dynamic recrystallization(DRX)characteristic values were calculated based on the Cingara-McQueen model,and the grain distribution under different conditions was observed and analyzed.Significantly,the action mechanisms of carbides on the DRX were illuminated.It was found from a functional relation between average grain size and Z parameter that grain size increased with increasing temperature and decreasing strain rate.Optimal parameters for the hot deformation were determined as 980-1005℃~0.01-0.015 s^(−1)and 1095-1110℃~0.01-0.037 s^(−1)at the strain ranging from 0.05 to 0.8.Increasing the strain rate appropriately during deformation process was suggested to obtain fine and uniformly distributed carbides.Besides,an industrial grade forging deformation had also verified practicability of the above parameters.展开更多
为了探究渣层厚度对熔融热解炉底吹工艺过程中熔池流动性的影响,以200 kg熔融热解炉为研究对象,基于流体体积(volume of fluid,VOF)方法,构建了熔融热解炉底吹模型,通过模拟多元炉料的熔分过程,确定了不同原料配比下熔池中钢液/渣层与...为了探究渣层厚度对熔融热解炉底吹工艺过程中熔池流动性的影响,以200 kg熔融热解炉为研究对象,基于流体体积(volume of fluid,VOF)方法,构建了熔融热解炉底吹模型,通过模拟多元炉料的熔分过程,确定了不同原料配比下熔池中钢液/渣层与原料的质量比及渣层厚度.结果表明:使用70%废钢+30%直接还原铁(DRI),80%废钢+20%DRI,90%废钢+10%DRI进行熔分后,渣层厚度分别为118,74,41 mm,DRI占比越高,渣层厚度越大;在底吹流量(标准状况)为0.2 m^(3)/h的条件下,随着渣层厚度的增大,钢液上部及渣层的流场分布更均匀,流速也更高,钢液中下部的低流速区域逐渐扩大,熔池内流动死区体积也在增大,渣层上的渣眼面积逐渐减小直至消失,钢-渣界面的速度则先降低后升高;当以80%废钢+20%DRI作为冶炼原料时,熔池的流动性最优.展开更多
随着能源与环境问题的日益突出,在保证安全性的前提下,实现车身轻量化是汽车工业发展的主要方向之一。先进高强钢(AHSS)兼具高强度和良好的成形性,是最重要的汽车轻量化材料,然而,长期以来突出的镀锌质量问题使其发展面临巨大挑战,特别...随着能源与环境问题的日益突出,在保证安全性的前提下,实现车身轻量化是汽车工业发展的主要方向之一。先进高强钢(AHSS)兼具高强度和良好的成形性,是最重要的汽车轻量化材料,然而,长期以来突出的镀锌质量问题使其发展面临巨大挑战,特别是对于高等级AHSS而言,表面质量控制问题始终未能得到有效解决。在生产过程中,钢中Si、Mn、Al等亲氧性元素会发生选择性氧化,在退火过程中表现尤为显著。由于表面氧化物的形成,镀锌液与基体的接触与润湿受到阻碍,进而抑制了Fe 2Al 5-x Z x中间层的形成,导致漏镀和镀层结合力差等镀锌缺陷。退火选择性氧化问题被普遍认为是制约AHSS可镀性的最大障碍。基于近20年的相关研究,首先介绍了退火选择性氧化与可镀性的内在联系,包括表面氧化物覆盖率、形貌及尺寸和化学态对可镀性的影响,而后对AHSS退火选择性氧化的影响因素及改善措施进行了综述和分析,包括退火露点和合金元素调控的影响及调控,最后对改善退火选择性氧化以获得高可镀性、高表面质量AHSS的技术路径进行了展望。展开更多
基金support from Open Project of State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing(No.41622030)Danyang Coinch New Material Technology Co.,Ltd.
文摘The hot deformation behavior and microstructure evolution of industrial grade American Iron and Steel Institute(AISI)M35 high-speed steel produced by electroslag remelting at different parameters were investigated.The results indicated that grains coarsening and M2C carbides decomposing appeared in the steel at 1150℃for 5 min,and the network carbides were broken and deformed radially after the hot deformation.A constitutive equation was determined based on the corrected flow stress-strain curves considering the effects of friction and temperature,and a constitutive model with strain-compensated was established.The dynamic recrystallization(DRX)characteristic values were calculated based on the Cingara-McQueen model,and the grain distribution under different conditions was observed and analyzed.Significantly,the action mechanisms of carbides on the DRX were illuminated.It was found from a functional relation between average grain size and Z parameter that grain size increased with increasing temperature and decreasing strain rate.Optimal parameters for the hot deformation were determined as 980-1005℃~0.01-0.015 s^(−1)and 1095-1110℃~0.01-0.037 s^(−1)at the strain ranging from 0.05 to 0.8.Increasing the strain rate appropriately during deformation process was suggested to obtain fine and uniformly distributed carbides.Besides,an industrial grade forging deformation had also verified practicability of the above parameters.
文摘随着能源与环境问题的日益突出,在保证安全性的前提下,实现车身轻量化是汽车工业发展的主要方向之一。先进高强钢(AHSS)兼具高强度和良好的成形性,是最重要的汽车轻量化材料,然而,长期以来突出的镀锌质量问题使其发展面临巨大挑战,特别是对于高等级AHSS而言,表面质量控制问题始终未能得到有效解决。在生产过程中,钢中Si、Mn、Al等亲氧性元素会发生选择性氧化,在退火过程中表现尤为显著。由于表面氧化物的形成,镀锌液与基体的接触与润湿受到阻碍,进而抑制了Fe 2Al 5-x Z x中间层的形成,导致漏镀和镀层结合力差等镀锌缺陷。退火选择性氧化问题被普遍认为是制约AHSS可镀性的最大障碍。基于近20年的相关研究,首先介绍了退火选择性氧化与可镀性的内在联系,包括表面氧化物覆盖率、形貌及尺寸和化学态对可镀性的影响,而后对AHSS退火选择性氧化的影响因素及改善措施进行了综述和分析,包括退火露点和合金元素调控的影响及调控,最后对改善退火选择性氧化以获得高可镀性、高表面质量AHSS的技术路径进行了展望。
