P91主蒸汽管道焊缝断裂韧度与其它力学性能的关系

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。

THE RELATIONSHIP AMONG THE FRACTURE TOUGHNESS AND OTHER MECHANICAL PROPERTIES OF WELDS IN A P91 MAIN STEAM PIPE

An experimental study on the tensile strength, impact toughness ,hardness and fracture toughness of two kind weld in a P91 has been carried out.The results show that R weld having the higher strength and hardness, the lower impact toughness is of the lower fracture toughness;D weld having the lower strength and hardness, the higher impact toughness is of the higher fracture toughness. The lower toughness of R weld results from coarse grain,network grain boundary and the higher electric current and linear energy in welding process. The lower strength and hardness, the higher fracture toughness of D weld is related to the higher temperature during postweld second heat treatment.The measured conditional KIC (Kq ) of R weld using three-point bend specimens (SEB)with 12mm thick is almost equal to the gained effective KIC of R weld using compact specimens(CT) with 25mm thick.