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对不同晶粒尺寸C-Mn钢低温缺口及裂纹断裂韧性进行了研究。结果发现:在-196～-30℃范围内,细晶钢的缺口断裂韧性显著高于粗晶钢;而在-110℃时粗晶钢裂纹断裂韧性接近或反而高于细晶钢,前者的平均值明显高于后者。粗晶钢最低韧性试样启裂点距预裂纹的距离小于细晶钢而韧性却高于细晶钢,从而否定了粗晶裂纹断裂韧性商是由于其具有大的特征距离(RKR模型)的观点。在缺口试样中细晶钢的σ_f~*/σ_(?)高于粗晶钢,而在裂纹试样中,细晶的σ_f~*/σ_(?)接近戏反而低于粗晶,这是粗、细晶粒钢缺口及裂纹断裂韧性变化不一致的主要原因,也说明σ_f~*/σ_(?)是一个有价值的韧性参量。
The fracture toughness and fracture toughness of C-Mn steel with different grain sizes were studied. The results show that the notch fracture toughness of fine-grained steel is significantly higher than that of coarse-grained steel in the range of -196 ℃ to -30 ℃, while the fracture toughness of the coarse-grained steel is similar to or higher than that of fine-grained steel at -110 ℃ The average was significantly higher than the latter. The minimum crack toughness of coarse-grained steel is smaller than that of fine-grained steel but higher than that of fine-grained steel, thus negating the fracture toughness of coarse-grained cracked steel due to its large characteristic distance (RKR model) View. The σ_f ~ * / σ_ (?) Of the fine-grained steel is higher than that of the coarse-grained steel in the notched specimens, while the σ_f ~ * / σ_ (?) Is the main reason for the inconsistent changes of the fracture toughness of the coarse and fine grain steel and the crack. It also shows that σ_f ~ * / σ_ (?) Is a valuable toughness parameter.