锰对低碳耐候钢组织与强韧性的影响

在真空感应炉冶炼了2炉不同锰质量分数的低碳耐候钢，利用热模拟机和金相显微镜分析了其组织特征和相变规律，并通过室温拉伸、冲击实验且结合断口分析表征了实验钢的强韧性。热模拟实验表明，低碳高锰耐候钢组织在低冷速下（＜1 ℃/s)为铁素体＋少量珠光体，而在较大冷速内(1～10 ℃/s)为贝氏体＋铁素体复相特征，随冷却速度的增加则钢中贝氏体增多。分析轧态组织表明，2组实验耐候钢中主要组织均为等轴铁素体；增加钢中锰则其强度明显增大，虽塑性和冲击韧性有所降低，但仍可获得良好的强韧性组合。

Influence of Mn Content on Microstructure and Strength and Toughness of Low Carbon Weathering Steel

Two types of low carbon weathering steel with different Mn content were produced in vacuum induction furnace. The microstructure characteristic and phase transformation regularity were analyzed by thermal simulator and metallographic microscope. Strength and toughness of experimental steel was characterized by room-temperature tensile test and impact test combining fracture analysis. The microstructure characteristic of weathering steel bearing low carbon and high manganese is ferrite and a small amount of pearlite with low cooling rate(<1 ℃·s-1), but duplex microstructure of bainite and ferrite is gained at a rather large range of cooling rate(1～10 ℃·s-1), moreover, the volume fraction of bainite is improved with cooling rate increasing. The dominant microstructure of two experimental steel rolling plates is equiaxed ferrite. Strength of weathering steel is increased remarkably when Mn content increases and plasticity and toughness are decreased somewhat. Excellent combination of strength and toughness is gained.