冷却工艺对700MPa级低碳贝氏体钢M/A岛的影响

Efects of Cooling Process on M/A Islands of 700 MPa Grade Low Carbon Bainitic Steel

利用Gleeble-3500热模拟试验机对700 MPa级低碳贝氏体钢进行了终冷温度、冷却速度和终轧温度等三要素的多水平正交试验,研究了不同冷却工艺对M/A岛的影响。结果表明,随着终冷温度的升高,700 MPa级低碳贝氏体钢中转变形成的M/A岛逐渐从点状变为球粒状,再到不规则形状的多面体,且M/A岛颗粒也逐渐变大,在650℃时还有明显粗化现象。随着冷却速度的升高,M/A岛的方向性逐渐明晰,呈弥散分布,且颗粒逐渐变细小,数量增多。终轧温度对低碳贝氏体钢M/A岛的影响小于终冷温度和冷却速度的影响。

By using Gleeble - 3500 thermal simulation machine, multi - level orthogonal experiment of final cool- ing temperature, cooling rate and finish wiling temperature have been performed on 700 MPa grade low carbon bainitic steel （LCBS） to study the effects of different cooling processes on M/A islands. The results show that M/A islands formed in 700 MPa grade low carbon hainitie steel during transition gradually changed with the final cooling temperature increase from dot to spherical shape and further to irregular shape of polyhedron while gradually growing. At 650 ~C, M/A islands have obvious roughening tendency. With the increase of cooling rate, M/A islands show a clear orientation and dispersively distribute, while the granular structure gradually become finer , and the number increases. The finish rolling temperature has less effects than final cooling temperature and cooling rate on M/A islands of low carbon bainitic steel.