共查询到20条相似文献,搜索用时 203 毫秒
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对加氢反应器球封头与筒体连接处的结构进行了有限元应力分析计算,并以¢4400大型加氢反应器为例,分别对半球形封头及球缺形封头连接的两种结构形式进行了详细的应力分析,最终选择出一种较合理的结构,为加氢反应器的设计提供了可靠的依据。 相似文献
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球形封头在其直边段易发生折皱和开裂,残余应力过大是造成其缺陷的根本原因之一.针对无损X射线衍射法、有损全释放法这两种残余应力测试方法的检测原理、测试方法及应用特点等方面进行了分析介绍.以12Cr2Mol R(H)材料为例,采用两种方法分别测量了球形封头热冲压成形后的外壁残余应力值.揭示了封头外壁残余应力分布规律:封头外壁的残余应力值由底部开始逐渐增大,过渡段为应力值转折区域,进入直边段后,残余应力值达到最大.通过对比发现:两种测量方法测得的残余应力变化规律相似;全释放法测得的残余应力值较大;残余应力值在封头外壁直边段部分达到最大. 相似文献
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T形接头在各种钢结构制造过程中得到普遍应用,其焊接残余应力的存在,直接影响到铜结构的强度和承载能力.由于现阶段控制和消除残余应力能力还不够成熟,很多方法只能很小部分地控制和消除残余应力,因此残余应力大量的留在T形接头焊接结构件上.为了保证焊接结构的安全可靠性,研究T形接头焊接应力分布规律的影响意义重大.本文利用HZ-21三维应力分布磁测仪测试了T形结构构件的焊接应力,分析了T形焊接接头构件的焊接顺序、焊接热输入不同时引起的焊接应力的变化规律.试验结果表明:Q235B钢以T形接头焊接时,焊接顺序不同,焊接应力的分布也不尽相同;焊接热输入较大时所产生的焊后24h应力分布较均匀,而焊接热输入较小时所产生的焊后24h应力分布变化较大.对T形结构件焊接时选取合理的焊接顺序和适当的焊接热输入具有一定指导意义. 相似文献
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制造了反应堆压力容器顶盖和控制杆驱动机构(CRDM)管座贯穿件J形密封焊模拟件,测试了焊接过程温度和焊后残余应力;采用分段移动温度热源模型和热力耦合方法实现了三维焊接温度场和应力场的高效计算,并与试验结果进行了比较;基于模拟的三维残余应力场研究了J形密封焊的应力分布特征. 结果表明,采用的模型和方法能实现J形密封焊残余应力的高效数值计算,计算和试验结果符合较好;J形密封焊缝上的纵向应力大于轴向应力,贯穿件内外壁应力不均匀,焊缝和贯穿件坡上和坡下区域的应力大于侧坡区域应力. 相似文献
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半管夹套焊接时不可避免产生残余应力,容易导致其焊接部位开裂泄漏.文中对不同坡口形式的半管夹套进行焊接试验,并利用有限元软件ABAQUS对焊接温度场及残余应力进行数值模拟.结果表明,不开坡口,加热温度不足以使夹套和筒体接触界面的金属完全熔化;开2 mm平行坡口时,焊缝根部温度未达到熔点,焊缝金属流动不足以填充根部间隙,产生未焊透;开45°外坡口,能保证完全焊透,且焊缝成型较好,焊缝根部的残余应力比不开坡口降低33%,筒体残余应力整体降低35%,有利于降低应力腐蚀开裂的敏感性.在实际焊接时,应开坡口焊接,禁止不开坡口或采用2 mm平行坡口. 相似文献
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《Science & Technology of Welding & Joining》2013,18(3):255-264
AbstractDevelopments in some difficult repair welding technologies in Japan during the past decade are reviewed. The topics covered include the repair welding of bridges in service, the temper bead method which makes it possible to omit post-weld heat treatment (PWHT) of repaired pressure vessels, the seal welding of a reactor vessel in which stress corrosion cracks were detected, low heat input repair welding of neutron irradiated stainless steel and nickel based alloys, the prevention of solidification cracking in repair welding of aged heat resistant cast steels, the development of welding materials for the mending of single crystal nickel based superalloy turbine blades, underwater repair welding of nuclear reactors, the reduction of residual stresses in repair welding, and an ultrasonic testing method for nickel based weld metals. The local PWHT of creep resistant ferritic steel tubes is also reviewed. 相似文献
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针对国产脉动真空灭菌器内腔焊缝处多次开裂现象,围绕焊接残余应力及消除方法进行了系列研究.根据市场上灭菌器异种钢间断角焊缝特征设计了7种组合结构焊板,应用X射线法定量给出了残余应力分布规律,并对用焊后浇水速冷处理工艺消除残余应力的尝试进行了试验验证.结果表明,各种焊板残余应力均达到屈服应力,由此引起的应力腐蚀与腐蚀疲劳是灭菌器内腔开裂的直接原因;二氧化碳焊接工艺残余应力较焊条电弧焊高10%~22%,残余应力与加强筋类型基本无关;浇水速冷处理工艺可有效降低表面残余应力,降幅达50%~70%,提高疲劳极限12%~14%.有效降低焊接残余应力是解决内腔开裂的重要途径. 相似文献
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ABSTRACTStress corrosion cracking is one of the aging phenomena for the major structure components in nuclear power plant. During the operation of a power plant, stress corrosion cracks are initiated and grown especially in dissimilar weldment of primary loop components. Among the three factors (susceptible material, residual stress, and corrosive environment) which make the SCC, the residual stress becomes a critical factor for stress corrosion crack when it is difficult to improve the material of the components and their environment under operating conditions. In this study, stress corrosion cracks were artificially produced on STS (stainless steel) 304 pipe itself by control of welding residual stress. The instrumented indentation technique and 3D finite element method (FEM) analysis (using ANSYS 12) were used to evaluate the residual stress values in the GTAW area. As the result of both FEM analysis and experiment, the stress corrosion crack was quickly generated and could be reproduced, and controlled by welding residual stress. Also non-destructive evaluation signals by Acoustic Emission will be discussed for the initiation and growth of SCC.This paper is part of a supplementary issue from the 17th Asia-Pacific Corrosion Control Conference (APCCC-17). 相似文献
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Effects of surface treatment techniques like laser and shot peening on stress corrosion cracking (SCC) susceptibility of friction stir welded (FSW) 7075 aluminum alloy joints were investigated. This study had two parts; the first part investigated the peening effects on stress corrosion cracking susceptibility in FSW samples by slow strain rate testing in a 3.5% NaCl solution. The second part of the study investigated the effects of peening on corrosion while submerged in a 3.5% NaCl solution with no external loads applied. No signs of corrosion pitting or SCC were evident on any of the tensile samples during the slow strain rate testing. The FSW plates exposed in 3.5% NaCl solution for 60 days were inspected periodically for signs of corrosion and stress corrosion cracking in the areas expected to have residual stresses due to welding. Pitting corrosion was seen on the samples, but even after 60 day exposure no stress corrosion cracking was detected on any of the peened or unpeened samples. 相似文献
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The residual stress evolution in a safe-end/nozzle dissimilar metal welded joint of CAP1400 nuclear power plants was investigated in the manufacturing process by finite element simulation. A finite element model, including cladding, buttering, post-weld heat treatment (PWHT) and dissimilar metal multi-pass welding, is developed based on SYSWELD software to investigate the evolution of residual stress in the aforementioned manufacturing process. The results reveal a large tensile axial residual stress, which exists at the weld zone on the inner surface, leads to a high sensitivity to stress corrosion cracking (SCC). PWHT process before dissimilar metal multi-pass welding process has a great influence on the magnitude and distribution of final axial residual stress. The risk of SCC on the inner surface of the pipe will increase if PWHT process is not taken into account. Therefore, such crucial thermal manufacturing process such as cladding, buttering and post-weld heat treatment, besides the multi-pass welding process, should be considered in the numerical model in order to accurately predict the distribution and the magnitude of the residual stress. 相似文献