BM510L汽车大梁钢的连续冷却转变曲线

Continuous Cooling Transformation Curve of BM510L Steel for Automobile Frames

采用膨胀法在Gleeble-3500型热模拟试验机上测定了BM510L钢在不同冷速下连续冷却时的膨胀曲线及连续冷却转变曲线(CCT曲线);利用光学显微镜、显微硬度计研究了BM510L钢连续冷却过程中奥氏体转变后的组织和显微硬度。结果表明:随着冷速的提高,铁素体转变开始温度降低,珠光体转变终了温度也逐渐降低,当冷速大于1℃·s-1时,组织中开始发生贝氏体转变,当冷速为15℃·s-1时,组织已完全转变为贝氏体组织;随着冷速的提高,其显微硬度逐渐增大。

The dilatometric curves and continuous cooling transformation( CCT) curves of BM510L steel at different cooling rates were measured in Gleeble-3500 thermal simulating test machine by dilatometric measurement. The microstructure and microhardness of BM510 L steel after transformation of austenite in continuous cooling process were studied by optical microscopy( OM) and microhardness tester. The results show that as the cooling rate increases,both the initiate temperature of ferrite transformation and the terminal temperature of pearlite transformation decrease. The bainite is obtained in the microstructure at the cooling rate above 1 ℃ ·s- 1,and the microstructure is totally bainite at the cooling rate of 15 ℃ ·s- 1. The hardness increases with the increase of cooling rate.