摘要
采用热力学计算、X射线衍射、扫描电镜和显微硬度测试等分析了临界退火工艺对0.3C-5Mn-3Al热轧钢显微组织的影响。结果表明:两相区保温过程中,细小渗碳体颗粒先析出后溶解,奥氏体晶粒生长和元素配分持续进行,大尺寸或低C/Mn含量的奥氏体在水淬过程中转变为马氏体,残留奥氏体(RA)平均晶粒宽度在0.4-1μm之间。随退火温度增加,残留奥氏体含量(VRA)峰值从39.8vol%(720℃)增至47vol%(800℃);随保温时间延长,720℃处理实验钢残留奥氏体含量逐渐增加并趋于稳定值,800℃处理实验钢残留奥氏体含量在5min处达到峰值,而后连续降低至8.1vol%(90 min);对760℃处理实验钢而言,残留奥氏体含量在36.0-44.8vol%之间波动,可能与各阶段非同步进行的C和Mn元素配分过程有关。合理调整临界退火温度和时间,可获得残留奥氏体含量高于40vol%的0.3C-5Mn-3Al超细晶钢。
The effect of intercritical annealing process on microstructure of 0. 3C-5Mn-3Al hot rolled steel was analyzed by means of thermodynamic calculation , X-ray diffraction, scanning electron microscopy and microhardness test. The results show that in the process of annealing in two-phase region, the fine cementite particles are precipitated and dissolved, the austenite grain growth and element partitioning proceed continually, the austenite with large size or low C/Mn content is transformed into martensite in the process of water quenching, and the average grain width of retained austenite ( RA) is between 0. 4μm and 1 ptm. With the increase of annealing temperature, the peak value of retained austenite content ( VRA ) increases from 39. 8 vol%( 720℃) to 47 vol%( 800 ℃). With the increase of the holding time, the retained austenite content of the experimental steel treated at 720 ℃ gradually increases and tends to stabilize , and the retained austenite content of the experimental steel treated at 800℃ reaches the peak value at 5 min and then decreases to 8. 1 vol% at 90 min. For the experimental steel treated at 760℃, the retained austenite content fluctuates between 36. 0 vol% and 44. 8 vol%, which may be related to the non-synchronous partitioning process of C and Mn elements at different stages. The ultra-fine 0. 3C-5Mn-3Al steel with the retained austenite content higher than 40 vol% can be obtained by adjusting the intercritical annealing temperature and time reasonably.
作者
朱延山
张继明
曲锦波
罗咪
ZHU Yan-shan;ZHANG Ji-ming;QU Jin-bo;LUO Mi(Institute of Research of Iron and Steel ( IRIS ) ,Sha-sleel,Zhangjiagang 215625 ,China)
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2019年第7期101-108,共8页
Transactions of Materials and Heat Treatment
关键词
临界退火
残留奥氏体
元素配分
超细晶
intercritical annealing
retained austenite
element partitioning
ultra-fine grain
