钒改进钢再热裂纹超声对比试块及检测工艺研究

发布时间：2018-03-14 16:57

本文选题：钒改进钢　切入点：再热裂纹　出处：《浙江工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：加氢反应器是现代炼油工业的重大关键设备,自20世纪60年代起加氢反应器广泛采用2.25Cr-1Mo钢进行制造。20世纪70年代起,随着煤液化新工艺的发展,人们开发了比传统Cr-Mo钢更具优势的钒改进钢。2007年,再热裂纹在欧洲的钒改进钢加氢反应器中被发现,经研究,再热裂纹是在消应力处理(ISR)或焊后热处理(PWHT)后产生,有一定的隐蔽性,因而由其引起的事故具有不可预见性,且危害性极大,故国内外科技人员对钒改进钢再热裂纹的预防、检测技术高度关注。目前厚壁加氢反应器多采用TOFD技术对焊缝进行检测,实现对再热裂纹的检测,将对钒改进钢加氢反应器的设计、制造及安全运行提供一定的技术保障,具有一定的工程意义。本文在总结钒改进钢再热裂纹产生机理和形貌特征的基础上,结合TOFD检测所需条件,参考API标准,设计并制作了模拟再热裂纹的对比试块。通过TOFD检测、超声检测,实现了对模拟再热裂纹的检出和定量。本文的主要工作和成果如下:(1)根据钒改进钢再热裂纹产生机理和形貌特征,设计制作了模拟再热裂纹的对比试块,研究适用于模拟埋藏小缺陷的试块加工方法。(2)TOFD试验发现:采用国内目前的NB/T 47013.10(JB/T 4730.10)标准推荐的检测通道数是可以检测到一定尺寸再热裂纹的。(3)和常规非平行扫查不同,采用特殊B扫描进行缺陷检测时,表面盲区较小,且TOFD图像中近表面缺陷可以清楚地显示出来,并且可以对缺陷位置和自身高度进行精确测量。(4)TOFD+UT检测工艺,即特殊B扫查方式的TOFD检测、手工脉冲反射式超声检测,可以实现对钒改进钢再热裂纹的检出和定量;TOFD检测可以对缺陷定深定高,精度较高,UT也可以对缺陷定深及定高,两者检测结果可相互验证。
[Abstract]:Hydrogenation reactor is a key equipment in modern oil refining industry. Since 1960s, 2.25Cr-1Mo steel has been widely used in hydrogenation reactor. Since 70s of the 20th century, with the development of new coal liquefaction process. In 2007, a reheat crack was found in a hydrogenation reactor for vanadium improved steel in Europe. It was studied that the reheat crack occurred after stress relief treatment (ISR) or post-weld heat treatment (PWHT). The accident caused by it is unpredictable and harmful, so the domestic and foreign scientists and technicians prevent the reheat crack of vanadium improved steel. At present, most thick wall hydrogenation reactors use TOFD technology to detect weld seam and realize the detection of reheat crack, which will provide certain technical guarantee for the design, manufacture and safe operation of vanadium improved steel hydrogenation reactor. On the basis of summarizing the mechanism and morphology of reheat crack in vanadium improved steel, combining with the condition of TOFD detection and referring to API standard, a contrast test block of simulated reheat crack is designed and made by TOFD. Ultrasonic testing has realized the detection and quantification of simulated reheat cracks. The main work and results of this paper are as follows: 1) according to the mechanism and morphology of vanadium modified steel reheat cracks, a contrast test block of simulated reheat cracks has been designed and made. This paper studies the processing method of test pieces suitable for simulating buried small defects. It is found that the number of detection channels recommended by NB/T 47013.10 / JB / T4730.10) is different from that of conventional non-parallel scanning, which can detect reheat cracks of a certain size. When special B scan is used for defect detection, the surface blind area is small, and the near surface defect in TOFD image can be clearly displayed, and the position and height of defect can be accurately measured. That is, special B scan TOFD detection, manual pulsed reflection ultrasonic detection, can realize the detection of reheat cracks in vanadium improved steel and quantitative TOFD detection can determine the depth of defects, and the accuracy of UT can also determine the depth and height of defects. The two results can be verified by each other.
【学位授予单位】：浙江工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE966

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