高钢级管线钢中M/A组元的控制工艺

Controlling process of M / A constituents in high grade pipeline steel

通过热模拟试验,借助于SEM、TEM和其它显微组织分析手段,研究了高钢级管线钢生产过程中主要控轧控冷参数对显微组织中M/A组元体积分数、颗粒尺寸和形态分布的影响。结果表明：提高终轧温度,试验钢显微组织粗化,M/A组元体积分数增加,颗粒尺寸增大,不规则形状的M/A数量增多;随着冷却速度增加,M/A组元体积分数降低,颗粒尺寸减小;在300-450℃内终冷时,M/A组元的体积分数和颗粒尺寸均在360℃附近出现了最小值,升高或降低终冷温度都将使M/A组元的数量和尺寸增多和增大。因此,在高钢级管线钢生产中,适当降低终轧温度、增加冷却速度、选取合理的终冷温度,是有效控制显微组织中M/A组元的形态分布、确保优异韧性的关键。

Effects of controlled cooling and controlled rolling parameters on volume fraction,particle size and pattern distribution of M / A constituents were studied by means of analysis methods of SEM and TEM based on thermal simulation experiments. The results show that microstructure of the tested steel is coarsened,volume fraction and particle size of M / A constituents and amount of irregular M / A are increased with the increasing of finish rolling temperature. Volume fraction and particle size of M / A constituents are decreased with the increasing of cooling rate. When the final cooling temperature is 300-450 ℃,minima of volume fraction and particle size of M / A constituents appear at about 360 ℃. Therefore,in the production of high grade pipeline steel,finish rolling temperature,cooling rate and the final cooling temperature are the key to control pattern distribution of M / A constituents and ensure excellent toughness of pipeline steel.