论文部分内容阅读
用Gleeble-1500热模拟试验机研究了RE微合金化免退火冷镦钢SWRCH35KM热变形后连续冷却过程相变规律和显微组织演变特征。结果表明,试验钢0.1~25℃/s冷速范围内均发生了铁素体和珠光体转变,冷速0.1~0.2℃/s时细小珠光体区有明显球化行为,而冷速在>2℃/s后开始出现针状铁素体和魏氏组织。为了获得均匀细小的铁素体基体加在线球化珠光体组织,需在斯太尔摩冷却线采用分段冷却控制思路,吐丝温度至750℃范围内冷速宜>2℃/s,抑制粗大先共析铁素体,而在750~680℃时冷速需1~2℃/s,以避免魏氏组织和针状铁素体;680~640℃珠光体转变温度区间冷速应≤0.1℃/s,以促进珠光体在线球化。
The phase transformation and microstructure evolution of SWRCH35KM after hot deformation of RE microalloyed annealed cold heading steel were investigated by Gleeble-1500 thermal simulator. The results show that the transformation of ferrite and pearlite takes place in the cooling rate of 0.1-25 ℃ / s in the test steel. The fine pearlite zone has obvious nodularity when the cooling rate is 0.1-0.2 ℃ / s, while the cooling rate is> Acicular ferrite and Wistarian tissue began to appear after 2 ℃ / s. In order to obtain a uniform and fine ferrite matrix plus pearlite microstructure, segmented cooling control strategy needs to be adopted in the Steiner cooling line. The cooling speed should be> 2 ℃ / s in the range of the spinning temperature up to 750 ℃ Coarse first proeutectoid ferrite, and 750 ~ 680 ℃ in the cooling rate of 1 ~ 2 ℃ / s, in order to avoid Wei organization and acicular ferrite; 680 ~ 640 ℃ pearlite transformation temperature range should be ≤ ≤ 0.1 ℃ / s, to promote the pearlite in-line ball.