X80钢隔水管焊接接头疲劳性能研究

发布时间：2018-08-15 17:34

【摘要】：钻井隔水管作为深海油气勘探开发中非常重要的一环,是否安全是目前隔水管研究的重中之重,因此,为了确保海洋钻井隔水管不会在计划寿命期内因为疲劳断裂而失效,对钻井隔水管进行疲劳性能分析就变得非常重要,而X80管线钢由于其高强韧性、耐蚀性被大量应用于隔水管的建造当中。X80钢所形成的隔水管焊接接头作为整个焊接构件中最脆弱的地方,具有比较高的疲劳强度是整个隔水管正常运行的保证。本文取样于X80钢隔水管部分管道,对焊接接头进行疲劳试验以及数值模拟以探究焊接接头的疲劳性能、疲劳影响因素以及找到提高其疲劳性能的方法。利用超声冲击应力消除设备、电液伺服疲劳试验机、光学显微镜(OM)、KJ3-3型压痕应力测试仪、扫描电子显微镜(SEM)和显微硬度仪等设备对焊接接头的组织性能和力学性能进行了分析。同时运用有限元分析软件ANSYS Workbench对焊接接头的寿命进行了模拟,并对不同形式的焊接接头疲劳性能进行了分析。研究结果表明:焊接接头的焊趾部位存在应力集中,容易发生疲劳断裂,去除余高之后会改善这一点并提高焊接接头的疲劳寿命4~6倍;超声冲击处理能够改善焊趾区表面形貌,形成圆滑过渡,还可细化表面晶粒,提升表面层硬度,并且消除了残余拉应力,产生有效的压应力,降低焊接接头的应力集中并提高疲劳寿命。对焊接接头疲劳性能的模拟计算表明,超声冲击以及去除余高可以提高焊接接头的疲劳寿命,去除余高效果比超声冲击效果更优;在不考虑残余应力影响的情况下,双面对称开设的坡口型式形成的焊接接头疲劳性能最为优异,U型坡口较V型坡口更好一些,Y型坡口相对较差;焊接接头的应力集中系数随着坡口角度的增加而降低,而钝边高度的大小对疲劳寿命影响不大;焊接接头的应力集中系数随着焊趾倾角的增大而增加,疲劳寿命随着焊趾倾角的增大而降低。
[Abstract]:As a very important part of deep-sea oil and gas exploration and development, the safety of drilling risers is the most important part of the current research on risers. Therefore, in order to ensure that offshore drilling risers do not fail due to fatigue fracture during their planned lifetime, It is very important to analyze the fatigue performance of drilling riser, and X80 pipeline steel is due to its high strength and toughness. Corrosion resistance is widely used in the construction of riser. The welded joint of riser formed by steel .X80 is regarded as the most vulnerable place in the whole welding component, and the high fatigue strength is the guarantee of the normal operation of the whole riser. In this paper, the fatigue test and numerical simulation of welded joints are carried out on the X80 steel riser pipe to investigate the fatigue properties of welded joints, fatigue influencing factors and ways to improve their fatigue properties. The microstructure and mechanical properties of welded joints were analyzed by means of ultrasonic shock stress relief equipment, electro-hydraulic servo fatigue testing machine, optical microscope (OM) KJ3-3 indentation stress tester, scanning electron microscope (SEM) and microhardness tester. At the same time, the life of welded joints is simulated by finite element analysis software ANSYS Workbench, and the fatigue properties of welded joints of different forms are analyzed. The results show that there is stress concentration in the toe of welded joint, and fatigue fracture is easy to occur. The fatigue life of welded joint can be improved by 4 ~ 6 times after removing the remaining height, and the surface morphology of weld toe can be improved by ultrasonic impact treatment. The smooth transition can also refine the surface grain, increase the hardness of the surface layer, eliminate the residual tensile stress, produce effective compressive stress, reduce the stress concentration of the welded joint and increase the fatigue life. The simulation results of fatigue properties of welded joints show that ultrasonic impact and removal of residual height can improve the fatigue life of welded joints, and the effect of removing residual high is better than that of ultrasonic impact, without considering the influence of residual stress, the fatigue life of welded joints can be improved by ultrasonic impact. The fatigue properties of welded joints formed by double-sided symmetrical groove are the most excellent. The U-type groove is better than the V-shaped groove, and the stress concentration factor of welded joint decreases with the increase of groove angle. The stress concentration factor of welded joints increases with the increase of toe inclination angle, and the fatigue life decreases with the increase of toe inclination angle.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE95;TG407

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