【作者】 乔馨；

【导师】 张红梅； 丛津功；

【作者基本信息】 辽宁科技大学 ， 材料加工工程， 2007， 硕士

【摘要】 当前,随着国民经济的高速发展,对石油、天然气的需求急剧增加,对管线钢的需求也相应地急剧增加。在激烈的市场竞争下,世界上各油气公司普遍接受采用更高强度级别的管线钢,以便可以采用高压输送油气而降低成本。因此,近年来高压输送和厚壁、高强度的管线已经成为管线建设的一个新的发展趋势。在管线建设的这种新的发展趋势中,针状铁素体管线钢由于具有优良的强韧性能、焊接性能、抗硫化氢开裂性能而具有广阔的应用前景。本文以鞍钢的产品微合金管线钢X65为研究对象,通过进行实验室模拟轧制实验,将控制轧制与控制冷却技术应用于微合金管线钢的生产过程中,探讨了微合金管线钢热变形过程中组织细化与性能变化的规律,同时研究了X65的显微组织与力学性能之间的关系以及针状铁素体管线钢的强化机制。从而,为实际工业大生产中通过TMCP工艺来改善管线钢的针状铁素体组织和提升管线钢的综合力学性能,提供了重要的理论基础和工艺依据。主要研究内容和研究方法如下:1.按照自行设定的工艺制度,利用实验室轧机进行实际控制轧制和控制冷却实验,在热轧实验中对X65管线钢采用两阶段多道次控轧和适当冷却速度控冷的TMCP工艺;2.对TMCP工艺后的X65管线钢进行金相试样的制备,并使用光学显微镜对试样进行显微组织观察和分析,研究不同的控轧控冷工艺参数对X65管线钢显微组织结构的影响规律;3.对TMCP工艺后的X65管线钢进行金属薄膜试样的制备,在透射电镜下对试样进行显微组织观察和分析,研究针状铁素体管线钢的强化机制;4.对TMCP工艺后的X65管线钢进行力学性能检测,探讨不同的控轧控冷工艺参数对X65管线钢力学性能的影响规律;5.综合分析各种实验结果,总结控轧控冷工艺参数对X65管线钢显微组织和力学性能的影响规律,揭示X65管线钢显微组织与力学性能之间的关系。从而在不改变现有管线钢化学成分的情况下,仅仅通过优化的TMCP工艺,进行管线钢的柔性化轧制,最终实现管线钢组织结构的优化和力学性能的提升。更多还原

【Abstract】 The demands for pipeline steels are being increased dramatically with the national economy development. In the fierce market competition, driven by the cost considerations, gas&oil transportation companies have readily adopted higher strength pipeline steels with thicker gauges to permit gas&oil transportation at higher pressures. As a result, recent construction of pipelines has shown a trend towards higher operation pressure with greater wall thickness and higher strength pipe. At the same time, acicular ferrite pipeline steels are becoming accepted as the prevalence for the new construction because of their high strength, excellent toughness, good weldability and satisfied hydrogen sulfide resistance.This thesis, applied controlled rolling and controlled cooling technology on the production of micro-alloyed pipeline steel X65 which was provided by Anshan Iron and Steel Group Corporation, by means of laboratory simulation test. Then we did research on the characteristics of the change of microstructures and properties at various deformation conditions, and clarified the relations between microstructures and mechanical properties of X65 and the strengthening mechanisms of acicular ferrite pipeline steels. The experimental aim was to offer the important theoretical foundation and technological basis for the improvement on microstructures and the enhancement on mechanical properties of acicular ferrite pipeline steels, which would be brought into effect through the technology of TMCP in the industrial manufacture. The main contents are given as follows:1. According to the process system designed by ourselves, the practical controlled-rolling and controlled-cooling tests were performed by using the rolling mill in the laboratory. And the improved TMCP schedules containing a two-stage multi-pass controlled rolling coupled with moderate cooling rates were applied to the hot rolling experiments.2. The metallographic specimens of X65 pipeline steel were prepared after the process of TMCP. The microstructures of the specimens were examined using optical microscope (OM). And the effects of different technological parameters of controlled rolling and controlled cooling on the microstructures of X65 pipeline steel were completely studied. 3. The metallic film specimens of X65 pipeline steel were prepared after the process of TMCP. The microstructures of the specimens were analyzed using transmission electron microscope (TEM). And the strengthening mechanisms of acicular ferrite pipeline steels were investigated comprehensively.4. The mechanical properties of X65 pipeline steel were tested after the process of TMCP. And the actions of different technological parameters of controlled rolling and controlled cooling on the mechanical properties of X65 pipeline steel were researched on exhaustively.5. Comprehensive analyzing all the experimental results, the effects of technological parameters of controlled rolling and controlled cooling on the microstructures and mechanical properties of X65 pipeline steel were generalized, and the relations between microstructures and mechanical properties of X65 pipeline steel were clarified thoroughly. Thus, the flexible rolling of pipeline steels would be obtained only by optimizing the process of TMCP, so as to achieve the improvement on microstructures and the enhancement on mechanical properties of pipeline steels, without changing their existing chemical compositions.更多还原