共查询到19条相似文献,搜索用时 250 毫秒
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堆焊有带极堆焊和手工堆焊两种,堆焊层常见的缺陷有气孔、针孔、夹渣、裂纹及未熔合等。夹渣、未熔合等缺陷大多平行于堆焊层表面,一般以纵波探伤为主。但是,堆焊层厚度一般在10mm以下,若直接从堆焊层表面用普通直探头进行探伤,由于近场长、盲区大而无法取得良好效果。为了有效地发现堆焊层中的缺陷,特别是奥氏体不锈钢堆焊层,宜采用盲区小、能量集中的双晶直探头,见附图。 相似文献
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介绍了百万千瓦级蒸汽发生器管板堆焊层缺陷形成的原因,针对某制造厂发生的管板堆焊层的质量问题,采用分析和试验的方法确定该缺陷对后续管子管板封口焊缝质量的影响,并提出了该质量问题的处理方案,为处理和提高管板镍基堆焊层的质量问题提供参考。 相似文献
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介绍了1000MW核电蒸气发生器管板堆焊技术,管板平面采用带极电渣堆焊,管板边缘采用焊条电弧堆焊.管板堆焊是核电设备蒸气发生器制造过程中的关键工序,堆焊质量直接影响着管板的耐腐蚀性能、管子-管板焊缝间的焊接质量以及蒸气发生器的制造进度.通过一系列试验,详细介绍了产品堆焊前的整个试验准备过程.为了保证管子-管板焊缝质量,... 相似文献
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提出了采用双晶探头(当翼板较厚时采用直探头)和斜探头组合的方法在翼板上进行探伤。该方法以双晶探头探伤为主,斜探头为辅,两种探头对同一个缺陷进行定位,判断准确,避免漏检和误判,而且检测速度快。 相似文献
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在奥氏体不锈钢堆焊层超声检测中,一般用斜探头检测堆焊层下母材中的再热裂纹。随着材料的改进和焊接技术的提高,这种再热裂纹已经非常少见。所以,有些规范和标准已不再要求用斜探头检测堆焊层。文章介绍了几种用斜探头发现的缺陷,强调了用斜探头检测堆焊层的必要性。 相似文献
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堆焊层厚度的精确测量对于堆焊材料的合理利用有重要意义。本文基于超声测厚原理,在超声波探伤仪和直探头校准的基础上,提出了等离子弧粉末堆焊层厚度测量的数学模型,实现了堆焊层厚度的精确测量。堆焊层厚度的测量分为三个步骤:首先测出母材的厚度;其次测出母材上方堆焊层的厚度;最后从堆焊层的金相照片中测出母材中熔焊层的厚度,从而根据提出的数学模型得到堆焊层的厚度。与游标卡尺测厚相比,该方法简便可行,检测速度快,可大大减轻检测人员的劳动强度。另外,难以采用游标卡尺测量的部位,也可采用本文提出的方法进行测量。 相似文献
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This article describes research on the reliability of ultrasonic testing methods for hot-rolled steel bars of 40–60 mm diameter. Comparison of testing methods is made using direct contact with the bars along the circumferential surface using a straight beam probe (‘S’ probe), a twin crystal probe where the probe face is contoured to the bar curvature (‘SR’ probe) and a straight beam probe with a delay block. The distribution state diagrams of the echo sound pressure and the effective testing range in the cross-section of the bars are obtained. The conclusion is that methods using the SR probe and the straight beam probe with the delay block produce better quality results for steel bars with diameters equal to or smaller than 60 mm, but the S probe is not suitable. 相似文献
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通过直探头、斜探头、TOFD (超声波衍射时差法)等方法,对S31603/Q345R复合板压力容器的径向裂纹进行无损检测以比较其缺陷检出能力;通过扫描电镜观察其微观结构,分析其失效机理;最后,通过数值计算分析其安全性能. 结果表明,直探头检测时回波面较小易导致漏检,TOFD检测时不锈钢粗晶粒产生的回波易掩盖径向裂纹产生的回波从而导致漏检,而斜探头因检测回波面大,检测效果优于直探头和TOFD,建议采用斜探头检测以确保径向裂纹的检出;通过扫描电镜发现爆炸复合板结合界面呈明显的正弦波状且存在元素相互扩散现象;且结合界面处存在的裂纹、空洞等缺陷使其强度降低;最后,通过数值计算分析发现该类裂纹的存在使得复合板压力容器存在较大的安全隐患. 相似文献
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Haoyu Huang Nozomu Sakurai Toshiyuki Takagi Tetsuya Uchimoto 《NDT & E International》2003,36(7):515-522
This paper describes an arrayed multi-coil probe, newly developed for the testing and crack sizing of steam generator tubes by eddy current testing (ECT). The testing speed, the high sensitivity to shallow cracks and the crack sizing are the present requirements in ECT. Because of the multi-coil arrangement, the arrayed probe has a high detection speed around the whole tube, without the need for rotation. It is realized from former studies that knowing the number of cracks, their directions, and their positions beforehand is of great help in crack sizing. Thus, not only the sensitivities but also the spatial resolutions are important. Numerical simulations are applied to help the design of the probe from the viewpoint of the crack sizing of steam generator tubes. Experiments show that the present probe provides both a high detectability and a remarkable capability of reconstructing the shallow cracks of a tube. 相似文献
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为解决中国聚变工程实验堆316L不锈钢焊缝超声波检测时,探头扫查空间受限、检测信噪比低的难题,提出了基于双晶面阵探头的相控阵超声检测方案.通过CIVA仿真,分析了不同聚焦参数下DMA探头的声场特征,确定对接接头的检测工艺.参考NB/T47013.3-2015《承压设备无损检测第3部分:超声检测》附录I,设计并制作了对比试块,验证了检测工艺下的声束覆盖和φ2 mm侧横孔信噪比.结果表明,DMA探头可以在有限的扫查空间内实现焊缝声束全覆盖,对比试块中不同位置的φ2 mm侧横孔信噪比大于15 dB.试验结果可为316L类不锈钢对接焊缝相控阵超声检测工艺制定提供参考. 相似文献
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《Science & Technology of Welding & Joining》2013,18(8):749-753
AbstractA weakly ionised plasma can be generated in stainless steel welding with a 10 kW fibre laser beam at the ultra high power density of ~1 MW mm–2 in Ar shielding gas. The objectives of this study are to obtain a fundamental knowledge of optical interaction between a fibre laser beam and the weakly ionised plasma, and to evaluate effects of the plasma on weld penetration. The optical interaction was investigated by the high speed video observation or the power meter measurement of another probe fibre laser beam, which passed horizontally through the weakly ionised plasma induced during bead on plate welding of a 20 mm thick type 304 plate with a 10 kW fibre laser beam of 0˙9 MW mm–2 in power density. The probe laser observed was refracted at 0˙6 mrad angle in average, which was much lower than the 90 mrad divergence of the focused fibre laser beam. The attenuation of the probe laser was measured to be ~4%, which was not mainly caused by Inverse Bremsstrahlung but by Rayleigh scattering. Moreover, a stable laser welding process could be produced at such ultra high power density that 11˙5 mm deep penetration was obtained even if the laser peak power was modulated 1 ms periodically from 10 to 8˙5 kW. It was consequently considered that the optical interaction between the 10 kW fibre laser beam and the weakly ionised plasma was too small to exert the reduction in weld penetration. 相似文献
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对304/Q345R不锈钢复合板常压储罐进行了超声衍射时差法技术研究应用.采用带有对接焊缝的表面盲区试块进行直通波盲区测定,对复合板焊接模拟试块进行检测,分析比较了基于覆材侧和基材侧的检测效果差异性,最后将制定的检测工艺应用于现场一台25000 m3不锈钢复合板常压储罐,检出埋藏裂纹1条并进行了解剖验证.结果表明:基于... 相似文献
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目的 探究激光熔覆薄板W6Mo5Cr4V2高速钢刀具材料过程中扫描速度对刀具基材热影响程度、基材热积累翘曲变形和微观组织、熔覆层物相组成的影响规律,找出适合于薄板高速钢刀具材料的扫描速度参数选择范围。方法 采用单一控制变量的实验,制备出一组单道熔覆样件,分析不同扫描速度对基材热影响形貌、基材翘曲变形、显微组织及硬度的影响特性。结果 热影响区随着扫描速度的提高而不断减小,沿着熔覆方向,其热量累积程度逐渐加大,热影响区面积沿着熔覆方向往两侧扩散。扫描速度为2 mm/s时,基材底面的变形量为0.077 mm,且变形从中心向边缘扩展,以熔覆道对应中心部位最为凸出;当扫描速度为3 mm/s以上时,变形量减少到0.03 mm以内;当扫描速度为4 mm/s时,熔覆层与基材左右结合边界的最大裂纹宽度降低为0.013 mm,且裂纹长度明显减少。不同的扫描速度只影响熔覆层的组织细化程度和最高硬度区间,对熔覆层强化机理和组织成分没有较大的影响。结论 在熔覆薄板高速钢刀具材料时,较快的扫描速度可以减少基材表面的热影响程度,较慢的扫描速度容易引起基材的“鞍型”翘曲变形。当选用3 mm/s以上的扫描速度时,基材的翘曲变形量可以有效的控制在0.03 mm以内,且提高扫描速度可以在一定程度上有效降低结合边界裂纹尺寸。 相似文献