中文摘要：

采用热模拟技术、显微分析方法和力学性能测试等手段,对X100管线钢在（α＋γ）临界区加速冷却工艺下组织性能的变化规律进行研究。结果表明,通过临界区的加速冷却方法,可使X100获得（B＋F）双相组织。这种双相组织使得X100管线钢具有连续屈服的能力,表现为高的初始应变硬化倾向和大的均匀变形能力。在初始加速冷却温度为830～850℃时的加速冷却,使得X100具有高的强度、塑性、形变强化指数、韧性和低的屈强比,表现出了优良的强韧水平。此时形成的以细小的贝氏体为主,辅以少量细小、高密度位错的铁素体的组织结构赋予了材料高的强韧特性。研究还表明,随初始加速冷却温度降低,铁素体体积分数增加,引起材料强度的降低和形变强化指数的增加。

英文摘要：

The influence of accelerated cooling in（＋） critical zone on the microstructure characterization and properties of an X100 pipeline steel is investigated by means of thermal simulation technique,microscopic analysis method and mechanical property testing.The results show that dual-phase microstructure of bainitic＋ferrit（B＋F） can be obtained by using accelerated cooling method in（＋） critical zone,and（B＋F） dual-phase microstructure has a continued yield capacity,high tendency of initial strain hardening and large uniform deformability.When accelerated cooling temperature is of 830~850 ℃ in critical zone,X100 pipeline steel can get excellent mechanical properties such as high strength-toughness,good ductility,high strain hardening exponent and low yield/tensile ratio because of the formation of fine bainite and ferrite with high density dislocation.When accelerated cooling temperature decreases,the strength of X100 pipeline steel decreases and its strain hardening exponent increases because of increasing of ferrite volume fraction.