Ti微合金化非调质钢中碳化物析出行为及其对再结晶的影响

通过Gleeble-3800热模拟试验机研究了变形温度850~1200 ℃,应变速率0.1 ~10 s^-1条件下Ti微合金化非调质钢的奥氏体动态再结晶行为。分析变形温度、变形速率、碳氮化物的析出行为对奥氏体动态再结晶的影响,计算动态再结晶激活能,获得动态再结晶状态图和热加工图。结果表明,随着Ti含量从0增加为0.042%和0.063%,钢中碳氮化物的析出量分别为0%、0.040%和0.038%,呈现出先增加后减少的趋势,相应的动态再结晶的激活能分别为360.218、394.015和378.247 kJ/mol,0.042%Ti含量的非调质钢激活能最高。通过功率耗散图和塑性失稳图的叠加得到了热加工图,获得了Ti微合金化非调质钢的最佳热加工工艺范围是900~1050 ℃的变形温度,0.1~0.2 s^-1的变形速率和1100~1200 ℃变形温度,0.1~4 s^-1变形速率。

Carbide precipitation behavior and its effect on recrystallization in Ti microalloyed non-quenched and tempered steel

Austenite dynamic recrystallization behaviors of Ti microalloyed non-quenched and tempered steels were studied by Gleeble-3800 thermal simulation machine with deformation temperature of 850-1200 ℃ and strain rate of 0.1-10 s^-1. The influences of deformation temperature, deformation rate, and precipitation behavior of carbonitrides on the dynamic recrystallization of austenite were analyzed, the activation energy of dynamic recrystallization was calculated, and the dynamic recrystallization state diagrams and processing maps were obtained. The results show that with the Ti content increasing from 0 to 0.042% and 0.063%, the carbonitride precipitation amount in the steels is 0, 0.040 % and 0.038 %, respectively, showing a trend of increasing at first and then decreasing. The corresponding activation energy of dynamic recrystallization of the tested steels is 360.218, 394.015 and 378.247 kJ/mol, respectively, and that with 0.042% Ti is the highest. The processing maps obtained by superposition of power dissipation diagram and plastic instability diagram show that, the optimal thermal processing ranges of the Ti microalloyed non-quenched and tempered steels are the deformation temperature of 900-1050 ℃ with the deformation rate of 0.1-0.2 s^-1, and the deformation temperature of 1100-1200 ℃ with the deformation rate of 0.1-4 s^-1.