微量铜和砷对Ti-IF钢铁素体相变行为和组织的影响

利用Gleeble 3800热模拟试验机,结合膨胀仪研究了微量铜和砷对连续加热过程和冷却过程中Ti-IF钢相变动力学的影响;结合光学显微镜和扫描电子显微镜,模拟研究了微量铜和砷对不同热轧终轧温度条件下TiIF钢的铁素体晶粒尺寸的影响。结果表明:与几乎不含铜和砷的Ti-IF钢相比,铜、砷的质量分数为0.08%、0.04%的Ti-IF钢中的铜和砷显著提高连续加热过程中Ti-IF钢奥氏体相变的开始温度和连续冷却过程中铁素体相变的结束温度。这主要是由于砷是封闭铁基奥氏体区的元素。由于微量砷提高铁素体相变的结束温度,导致铁素体晶粒尺寸反常粗大。因此,对于残余砷含量较高的Ti-IF钢,应适当控制较高的热轧终轧温度,以避免形成粗大的铁素体组织。

Influences of Trace Cu and As on Phase Transformation Behaviors of Ferrite and Microstructure in Ti-IF Steel

The effects of trace Cu and As on the phase transformation behaviors of Ti stabilized interstitial free (Ti-IF) steels during continuous heating and cooling were studied by means of Gleeble 3800 thermal simulator and dilatometer. The influences of trace Cu and As on the ferrite grain size under different final hot rolling temperatures were also investigated by the simulator, optical microscopy and scanning electron microscopy. The results show that compared to Ti-IF steel almost without Cu and As, the start temperature of austenite transformation during continuous heating and the finish temperature of ferrite transformation during continuous cooling are significantly increased by the addition of 0. 08% Cu and 0. 04% As (mass fraction) into Ti-IF steel. This is mainly due to that As is an element which closes the phase region of Fe-base austenite. Trace As could increase the finish temperature of ferrite transformation, resulting in abnormal coarse ferrite grains. Therefore, for Ti-IF steel with a high level of residual As, a high finish temperature of hot rolling should be properly used, in order to avoid the formation of coarse ferrite microstructure.