超级贝氏体钢中残留奥氏体的行为

Behavior of retained austenite in super bainite steel

针对超级贝氏体钢中残留奥氏体组织对钢的强韧性贡献,设计了试验用钢60Mn2SiCr。通过对样品完全奥氏体化后不同温度和时间的等温处理,并通过SEM、TEM和MAUD软件分析了在超级贝氏体组织中残留奥氏体的存在、分布及数量。结果表明,残留奥氏体以薄膜状分布在贝氏体铁素体条束之间或针片内部;随等温温度的变化,其数量存在极值现象,在钢的Ms点稍上温度等温处理,可以获得残留奥氏体体积分数极大值为17.64%。此时,钢的强度为1930 MPa,伸长率7.44%,断面收缩率15.66%,具有良好的强韧性配合。

The experimental steel 60Mn2SiCr was designed to investigate the contribution of retained austenite to the strength and toughness in super bainite steel .The existence , distribution and amount of the retained austenite in super bainite steel were analyzed by scanning electron microscope , transmission electron microscope and materials analysis using diffraction ( MAUD ) software after the samples were completely austenitized and austempered at different temperature for different time .The results show that the retained austenite in the shape of films is distributed among the ferrite lath or acicular plates .The maximum volume fraction of retained austenite of 17.64% in the super bainite steel is obtained when austempered slightly above the Ms point .Accordingly, the tensile strength, elongation and area reduction of the steel reach to 1930 MPa, 7.44%and 15.66%, respectively, and it has a good match of strength and toughness .