高韧性管线钢控轧控冷工艺优化研究

OPTIMIZATION OF TECHNOLOGIES OF CONTROLLEDROLLJNG AND CONTROLLED COOLING FOR HIGH TOUGHNESS PIPELINE STEEL

本文从提高我国输油、输气管线用热轧板卷的韧性出发，探讨了在热轧宽带钢连轧机上生产低碳高强度微合金Ｘ６０～Ｘ６５级管线钢的优化控制轧制与控制冷却工艺制度，研究了热变形过程中变形奥氏体的再结晶规律、轧后冷却过程中相变规律，以及整个加热、轧制、冷却、卷取过程中微合金元素碳、氮化物的固溶与析出行为。结果表明，该实验用钢的合理控轧控冷工艺为：奥氏体化温度为１２００℃，粗轧区开轧温度为１１５０℃，终轧温度为１０５０℃；精轧区开轧温度为９５０℃，终轧温度为８６０℃，轧后冷却速度为１５℃／ｓ，卷取温度为５５０℃。采用上述工艺，宝钢生产的Ｘ６０～Ｘ６５级管线钢板的冲击韧性值提高了１倍以上，其综合性能达到或接近日本进口钢板的实物水平。

In order to improve the toughness of domestic pipeline steel for carryingoil and gas,the optimization of technologies of controlled rolling and controlled coolingfor producing X60～X65 HSLA pipeline steel at hot wide strip rolling mill wasstudied.In this work the following subjects have been investigated includingrecrystallization of deformed austtenite during hot deformation ,phase transformation dur-ing subsequent cooling and solution and precipitation behavior of carbonitride ofmicroalloying elements in the course of heating, rolling,cooling and coiling ,The resultsindante thdt the reasonable process of controlled rolling and controlled cooling is as fol-lows: Heating temperature is 1200℃,initial and finish rolling temperatures are1150℃ and 1050℃ respotively in roughing zone;begining and finish temperaturesare 950℃and 860℃ respectively in finish rolling zone,cooling rdte after rolling is15℃/s,coiling temperature is 550℃。Using this technology,the toughness of theX60～X65 pipeline steel plate produced by Baogand is mors than twice as high astht of the plates produced before.The comprehensive property of this plat reaches orapproaches that of the imported steel plates from Japan.