钒氮含量对厚规格耐候钢力学性能的影响

摘要：采用拉伸试验机、光学显微镜、透射电镜分析了不同V、N含量对20mm厚规格耐候钢力学性能的影响规律。结果表明，V质量分数为0.04%~0.11%范围内钒氮耐候钢力学性能随着V含量的增加呈线性变化。V质量分数每增加0.01%，强度增加约14MPa、伸长率降低约0.3%；N质量分数在60×10-6~270×10-6范围内，w(V)∶w(N)=4~5时，可获得屈服强度600MPa以上、抗拉强度700MPa以上良好的强化效果，对应的铁素体晶粒尺寸约10μm。增加V、N含量有效促进更多V(C,N)的析出，在奥氏体相变过程中作为铁素体形核核心，进一步细化了铁素体晶粒。但铁素体晶粒随N含量增加并非持续细化，当形核质点数量达到饱和时，细晶强化作用将趋于峰值不再增加。同样随着V含量的增加，剩余部分的V在铁素体中析出，沉淀强化占主要作用。

Effect of vanadium and nitrogen content on mechanical properties of thick weathering steel

Abstract： The effects of different vanadium and nitrogen contents on the mechanical properties of 20mm thick weathering steel were analyzed by using tensile testing machine, optical microscope and transmission electron microscope. The results show that the mechanical properties of V N weathering steel change linearly with the increase of V content in the range of 0.04 wt.%-0.11 wt.%, When V content increases by 0.01%, the strength of the test steel increases by about 14MPa and the elongation decreases by about 0.3%; in the range of 60×10-6-270×10-6 of N content, when w(V)∶w(N)=4-5, good strengthening effects of yield strength above 600MPa and tensile strength above 700MPa can be obtained, and the corresponding ferrite grain size is about 10μm. Increasing the content of vanadium and nitrogen can effectively promote the precipitation of more V(C,N), which acts as the core of ferrite nucleation during austenite transformation and further refines the ferrite grains. However, the ferrite grain is not continuously refined with the increase of N content. When the number of nucleation points reaches saturation, the fine grain strengthening effect will tend to peak and will not increase. Similarly, with the increase of V content, the remaining V precipitates in ferrite, and the precipitation strengthening contribution accounts for the main role.