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研究了控制轧制低碳含铌钢铁素体混晶的定量评定、形成原因,影响因素以及对钢的机械性能的影响,试验结果表明,铁素体晶粒尺寸的不均匀性(即混晶)可用参数C.V_A评定.C.V_A定义为晶粒面积的标准差与平均面积之比。铁素体晶粒尺寸的C.V_A值与加热温度、轧制温度、未再结晶区的形变量及轧后冷速有关,进入未再结晶区轧前奥氏体晶粒平均直径d_A的影响最大。控轧钢中产生严重混晶的根本原因是形变未再结晶奥氏体促进γ→α转变形核不均匀性。 铁素体混晶对钢的屈服强度无明显影响,对钢的脆性转变温度的影响与平均晶粒尺寸d_(F)有关。
The quantitative evaluation, formation reason, influencing factors and the influence on the mechanical properties of the ferritic low-carbon niobium-containing ferritic mixed crystals were studied. The experimental results show that the ferrite grain size inhomogeneity ) Available parameters C.V_A rating.C.V_A is defined as the ratio of the standard deviation of the grain area to the average area. The value of C.V_A of ferrite grain size is related to the heating temperature, rolling temperature, the amount of deformation in the non-recrystallization zone and the cooling rate after rolling, and the influence of the average austenite grain diameter d_A before entering the non-recrystallization zone maximum. The fundamental reason for the severe mixed grains in controlled rolling is that the deformed unrecrystallized austenite promotes the nucleation inhomogeneity of γ → α transformation. Ferrite mixed crystal has no obvious effect on the yield strength of steel, and the effect on the brittle transition temperature of steel is related to the average grain size d_ (F).