摘要
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<sub>f</sub><sup>*</sup>/σ<sub>?</sub>高于粗晶钢,而在裂纹试样中,细晶的σ<sub>f</sub><sup>*</sup>/σ<sub>?</sub>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<sub>f</sub><sup>*</sup>/σ<sub>?</sub>是一个有价值的韧性参量。
Low temperature toughness of C-Mn weld steel with different grain sizes in notched and precrack specimens are investigated. The results indicate that fine grain steel has a higher toughness in notched specimen as compared with coarse grain steel over a temperature range from -196℃ to -30℃. At -110℃,however ,the minimum value of toughness in precracked specimen with coarse grain is a little higher than that in specimen with fine grain. The average value of the former is remarkably higher than that of the latter. This discrepance in behavior reveals that in precracked specimen with coarse grain the toughness value is the lowest among other coarse grain specimens but still higher than the lowest toughness of fine grain steel specimens and the distance of crack initiation site from the fatigue crack tip is ,however, shorter than that in the latter . This fact denies the argument that a higher toughness in precracked specimen with coarse grain is due to a larger characteristic distance for cleavage fracture. This is because ,mainly, of that the fine grain steel has a higher σf/σs, value in notch specimen but a closer or even lower value in precrack specimen. It is suggested that the σf/σs, value may be taken as an available parameter for the engineering evaluation of the toughness.
出处
《甘肃工业大学学报》
1992年第1期63-70,共8页
Journal of Gansu University of Technology
关键词
断裂机理
低温韧性
组织
C-MN钢
fracture mechanism, low temperature toughness, microstructure, characteristic distance, cleavage strength
