【摘要】 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。更多还原

【Abstract】 Hot compression deformation of non-annealed cold heading steel SWRCH35 KM with RE micro-alloyed was carried out on Gleeble-1500 thermal mechanical simulator to research continuous cooling transformation rule and microstructure evolution. The results show that Ferrite and pearlite transformation happens in cooling rate range of 0. 1-25 ℃/s,and Spheroidization behavior occurs in fine pearlite colony at cooling rate of 0. 1-0. 2 ℃/s. When the cooling rate is over 2 ℃/s,acicular ferrite and widmannstatten are observed. To obtain the microstructure of on-line spheroidized pearlite dispersed in fine and uniform ferrite matrix,step cooling strategy should be adopted in Stelmor cooling line. High cooling rate of over 2 ℃/s is benefit to restrain large proeutectoid ferrite from laying temperature to 750 ℃. Cooling rate should be 1-2 ℃/s at temperature range of 750-680 ℃ to avoid widmannstatten and acicular ferrite. Then cooling rate should be lower than0. 2 ℃/s at temperature range of 680-640 ℃ to improve on-line spheroidization of pearlite.更多还原