内压与外弯矩同时作用下带周向裂纹管子的断裂性能

FRACTURE BEHAVIOUR OF THE PIPES WITH CIRCUMFERENTIAL CRACK UNDER SIMULTANEOUSLY APPLIED INTERNAL PRESSURE AND BENDING MOMENT

本文主要描述了具有周向裂纹管子(或容器)在内压和外弯矩同时作用下的断裂性能。通过16个具有不同几何裂纹的管子(φ800×47×5000)的试验研究,可以得到,带周向裂纹的管子在内压与外弯矩同时作用下的承载能力与管子几何、材料强度与韧性有关,它的失效形式(泄漏或爆破)可以用爆破前泄漏曲线来加以评定,当管子具有较深的裂纹(t/s>0.8)时,管子会产生泄漏失效,而对具有浅裂纹的管子,通常以爆破的型式产生破坏。试验是以压水堆核电站主循环冷却回路的管子为对象,是以实际工况(P_i=15MPa,Mb=11.7MNm)作为试验条件进行的,试验结果表明,其穿透裂纹的临界长度与材料韧性有关,对韧性较好的材料(A_v>150J)20MnMoNi 55制的管子。它的临界长度为240mm(相应的周角为35°),而韧性较差的材料(A_v～50J)22NiMoCr37制的管子,相应的临界长度为100mm(周角15°)。当管子的裂纹长度达到或超过临界裂纹长度时,裂纹将不能产生止裂现象。

The present work describes mainly the fracture behaviour of the circumferentially cracked pipe (or pressure vessel) under simultaneously applied internal pressure and bending moment. Results of tests of 16 pipes (φ 800x47x5000mm) with different cracks under the operational conditions of PWR show that the load-carrying capacity is related to the dimension of the pipe and the crack, and strength and toughness of steel material. The failure form of pipe (leak or break) can be predicted with the aid of Leak-before-Break Curve. The pipe with deep crack (t/S>0.8) may fail through leaking, while the shallowly cracked pipe can lead to frequent bursting accident.