氢浓度对存在缺口的管道破裂的影响.pptVIP

Therefore, for assigned testing conditions, steel X52 is preferable than steel X70 from the point of view of local strength at notches. The steel X100 demonstrates quite high resistance against notch effect, but within close limits of hydrogen concentration variables 结论 实验条件：模拟在无氧，浸泡在近中性的NS4溶液中，施加张应力的运行环境。X100钢的抗吸氢能力最强并且随着其强度降低，抗吸氢的能力也降低。 Ui=F(CH)图形可以用于对在给定实验条件下API等级钢管氢脆的评价。 X70钢在空气和氢条件下缺口效应都很显著，因此，从缺口的局部强度角度看，X52比X70钢更好。X100除在接近极限氢浓度外抵抗缺口效应的能力都很强。 本论文首次考虑了加载速率、缺口等影响抵抗断裂的过渡氢浓度的因素。 临界氢浓度取决于材料特性、裂口半径、样本施加三轴应力的几何方式等因素。在实验中给定的缺口形状、三轴应力施加方式和钢材特性条件下，得到金属在缺口处的局部抗断裂能力有显著下降。而且得到随着钢材屈服应力和极限应力的增加临界氢浓度单调减少。 Thank you 2011214080 邓丛微 导师 帅 健 讲解思路 内容简介 研究对象和实验过程 结果和讨论 结论 内容简介 Nowadays, the pipe diameter has been significantly increased due a strong needs in energy carriers. At the same time, service pressure is expected to grow until 120 bars and, consequently, the constitutive yield stress of steels was increased. steel X52， steel X70 and steel X100 for conditions of hydrogen charging the factors of cathodic hydrogen charging, time of exposition, hydrogen concentration in metal and applied load were taken into account The relationship between hydrogen concentration and work of fracture initiation has been derived and discussed Nomenclature Nomenclature 研究对象和实验过程 研究对象：The objects of study were three API grade pipeline steels, namely: X52; X70 and X100. The specimens for tests were machined from real pipes (Table 1). The chemical composition of steels and their mechanical properties in air are given in Tables 2 and 3 respectively. The structural specificity of steels can be seen in Fig. 1. The specimen view and notch geometry are given in Fig. 2. The study was conducted in special soil solution NS4 with pH=6.6-6.7.Chemical composition of this environment is given in Table 4. The specimens were coated by special dielectric isolation, excepting the small area at the notch (Fig. 3) 实验条件 The size of auxiliary (counter) electrode was 20 x 40 mm Durin