氮对高强度钢筋用钒微合金化钢冲击韧度的影响

Effect of Nitrogen on Impact Toughness of Vanadium Microalloyed Steel for High-Strength Bar

检测了含氮量不同的三种V-N微合金高强钢筋用钢的冲击性能和显微组织。结果表明:三种钢的冲击韧度均随着含氮量的增大而提高,钢热轧后的显微组织为铁素体和珠光体。EBSD分析表明,钢的平均晶粒尺寸随含氮量的增大而减小,低取向晶界随含氮量的增加而减少,而高取向晶界随含氮量的增加而增多。采用扫描电子显微镜(SEM)分析了三种钢的冲击试样断口,结果显示,三种钢的低温冲击试样断裂面都由解理面和小凹坑撕裂边组成,随着钢的含氮量的增加,断裂面由大解离面转变为小解离面。

Three categories of V-N microalloy steels containing different amounts of nitrogen used for high-strength bar were subjected to impact property measurements and nicrostructural survey. The results indicated that as the nitrogen content increased so too did the impact toughness of the three categories of steel, and that microstructures of the steels after hot-rolling were ferrite and pearlite. From EBSD analysis it was seen that as the nitrogen content increased, the average grain size of the steels decreased, the low orientation grain boundary decreased, and the high orientation grain boundary increased. Fracture analysis of impact samples of the three kinds of steels was performed by scanning electron microscope（ SEM）, and, as a result, the fractured surfaces of the three kinds of low temperature impact samples were consisted of cleavage surface and small dimples, and with the increase of nitrogen content, the fractured surface changes from large cleavage surface to small cleavage surface.