The fracture toughness of SA508-Ⅲ steel was studied in the temperature range from room temperature to 320℃ using the J-integral method. The fracture behavior of the steel was also investigated. It was found that the...The fracture toughness of SA508-Ⅲ steel was studied in the temperature range from room temperature to 320℃ using the J-integral method. The fracture behavior of the steel was also investigated. It was found that the conditional fracture toughness （JQ） of the steel first decreased and then increased with increasing test temperature. The maximum and minimum values of do were 517.4 kJ/m^2 at 25℃ and 304.5 kJ/m^2 at 180℃, respectively. Dynamic strain aging （DSA） was also observed to occur when the temperature exceeded 260℃ with a certain strain rate. Both the dislocation density and the number of small dislocation cells effectively increased because of the occurrence of DSA; as a consequence, crack propagation was more strongly inhibited in the steel. Simultaneously, an increasing number of fine carbides precipitated under high stress at temperatures greater than 260℃. Thus, the deformation resistance of the steel was improved and the Jo was enhanced.展开更多
文中对 P91 钢两类焊缝的拉伸、冲击、硬度,特别是断裂韧性进行了试验研究。结果表明:强度、硬度高,冲击韧性低的 R 焊缝具有低的断裂韧度,强度、硬度低,冲击韧性高的 D 焊缝具有高的断裂韧度;R 焊缝的低韧性主要与其晶粒粗大、网状晶...文中对 P91 钢两类焊缝的拉伸、冲击、硬度,特别是断裂韧性进行了试验研究。结果表明:强度、硬度高,冲击韧性低的 R 焊缝具有低的断裂韧度,强度、硬度低,冲击韧性高的 D 焊缝具有高的断裂韧度;R 焊缝的低韧性主要与其晶粒粗大、网状晶界及焊接过程中焊接线能量和电流偏大有关,而 D 焊缝的低强度与高的断裂韧度则与焊后二次回火时温度过高有关。对于 R 焊缝,用厚度 12mm 的三点弯曲(SEB)试样测得的条件 KIC(Kq)与厚度 25mm 的紧凑拉伸(CT)试样测得的有效 KIC基本一致。展开更多
基金financially supported by the Major State Basic Research Development Program of China (No. 2011CB610506)the National Natural Science Foundation of China (Nos. 51371044 and 51171039)the Fundamental Research Fund for the Central Universities of China (No. N130410001)
文摘The fracture toughness of SA508-Ⅲ steel was studied in the temperature range from room temperature to 320℃ using the J-integral method. The fracture behavior of the steel was also investigated. It was found that the conditional fracture toughness （JQ） of the steel first decreased and then increased with increasing test temperature. The maximum and minimum values of do were 517.4 kJ/m^2 at 25℃ and 304.5 kJ/m^2 at 180℃, respectively. Dynamic strain aging （DSA） was also observed to occur when the temperature exceeded 260℃ with a certain strain rate. Both the dislocation density and the number of small dislocation cells effectively increased because of the occurrence of DSA; as a consequence, crack propagation was more strongly inhibited in the steel. Simultaneously, an increasing number of fine carbides precipitated under high stress at temperatures greater than 260℃. Thus, the deformation resistance of the steel was improved and the Jo was enhanced.
文摘文中对 P91 钢两类焊缝的拉伸、冲击、硬度,特别是断裂韧性进行了试验研究。结果表明:强度、硬度高,冲击韧性低的 R 焊缝具有低的断裂韧度,强度、硬度低,冲击韧性高的 D 焊缝具有高的断裂韧度;R 焊缝的低韧性主要与其晶粒粗大、网状晶界及焊接过程中焊接线能量和电流偏大有关,而 D 焊缝的低强度与高的断裂韧度则与焊后二次回火时温度过高有关。对于 R 焊缝,用厚度 12mm 的三点弯曲(SEB)试样测得的条件 KIC(Kq)与厚度 25mm 的紧凑拉伸(CT)试样测得的有效 KIC基本一致。
