SWRCH35KM冷镦钢热模拟试验分析

Analysis on Thermal Simulation Test of SWRCH35KM Cold Heading Steel

采用Gleeble-1500热模拟试验机测试了SWRCH35KM试验钢的连续冷却相变规律。通过在线球化热模拟试验,研究终轧后珠光体球化相变规律。不同冷却速度下均发生了铁素体珠光体转变,随着冷却速度增加,铁素体显微组织特征有所变化。冷却速度在2℃/s以下时,SWRCH35KM试验钢的金相组织为铁素体和珠光体,随着冷却速度逐渐增加,金相组织中不断出现针状铁素体并伴随有魏氏体组织,同时铁素体相比之前更为细化,其体积分数占比也逐渐降低。利用SWRCH35KM试验钢热模拟试验数据,按照组织相变规律,为了得到理想的金相组织,工业生产中将严格控轧控冷,尤其是斯太尔摩冷却线的控冷方式,保证获得细小铁素体和球化珠光体组织。

The phase transition law of continuous cooling for SWRCH35KM test steel is tested with Gleeble-1500 thermal simulated test machine. The phase transition law of spheroidization of pearlite after final rolling is studied by the thermal simulation test of online spheroidization. There are transformations of ferrite and pearlite at different cooling rates as well as the characteristics of microstructure for ferrite change with the increase of cooling rates. When the cooling rate is below 2 ℃/s, the metallographic structure of SWRCH35KM test steel is ferrite and pearlite. With the cooling rate gradually increases, the acicular ferrite along with Widmanstatten structure appear continuously in the metallographic structure. Meanwhile, the ferrite is more refined than before and its volume fraction is also gradually reduced. Based on the phase transition law of microstructure and with thermal simulation test data of SWRCH35KM test steel, rolling and cooling will be strictly controlled in industrial production in order to obtain ideal metallographic structure, especially the controlled cooling mode of Stelmor cooling line to ensure to obtain fine ferrite and spheroidized pearlite.