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研究了X120管线钢模拟控扎后冷却速度对组织性能的影响。扫描(SEM)和电子背散射衍射(EBSD)观察结果表明,提高控轧后冷速可以得到有效晶粒尺寸细小的板条贝氏体,有利于提高大角度晶界百分比,并结合力学性能测试结果,得出细小的板条贝氏体和大角度晶界有利于提高管线钢强度。利用透射电镜和能谱分析研究了实验钢中Nb、Ti等微合金元素的析出规律,冷速越大析出相粒子越细小弥散,沉淀析出强化效果越好。细晶强化、晶界强化和析出相强化等都是管线钢强化的主要方式。
The effect of cooling rate on the microstructure and properties of X120 pipeline steel after simulation of controlled-loading was studied. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) observations show that increasing the cooling rate after controlled rolling can produce small grain size of bainite, is conducive to increasing the percentage of large-angle grain boundaries, combined with the mechanical properties of the test As a result, it is concluded that fine lath bainite and large-angle grain boundaries improve the strength of the pipeline steel. The precipitation regularity of Nb, Ti and other micro-alloying elements in the experimental steel was studied by transmission electron microscopy and energy spectrum analysis. The larger the cooling rate, the finer the dispersed particles are, the better the precipitation strengthening effect is. Fine grain strengthening, grain boundary strengthening and precipitated phase strengthening are all the main ways to strengthen pipeline steel.