奥氏体不锈钢大型锻件超声波检测工艺及特点分析

奥氏体不锈钢大型锻件由于其材料和尺寸的特殊性,给超声波检测小平底孔当量缺陷的探测灵敏度确定及缺陷定量带来了困难.本文从仪器和探头的选择、衰减系数的测定和灵敏度调节等方面讨论了锻件的检测工艺方法.另外还结合实践经验对锻件超声检测中的一些特点进行了分析.     

螺旋埋弧焊管超声手工检测中影响缺陷定量因素的分析

针对螺旋埋弧焊管超声手工检测特点,结合螺旋埋弧焊管超声检测工艺和工艺检查中发现的常见问题,分析总结影响缺陷定量的相关因素。通过试验对比不同持拿力度、不同耦合剂、不同表面粗糙度及人工反射体内含物性质不同等情况下回波高度的差异,通过试验数据加深无损检测人员对影响缺陷定量相关因素的理解,加强日常检测工作中的规范操作,并为检测灵敏度补偿提供依据,提高缺陷定量精度。     

锻钢件超声检测标准对比分析

介绍了锻钢件常用超声检测标准,从适用范围、设备、探头、参考试块、灵敏度、扫查方向、缺陷分类、缺陷定量和评定、记录和验收等方面进行了对比分析,并提出了一些看法,为有关单位检验人员正确执行标准提供参考。     

第四专题 超声检测中缺陷的定量

超声检测中缺陷的定量也是人们研究的一个热点。缺陷定量可分为小于晶片直径的缺陷定量和大于晶片直径的缺陷定量。前者包括当量试块直接比较法、底波高度百分比法、当量计算法和AVG曲线法。后者包括相对灵敏度测长法、绝对灵敏度测长法、极坐标作图法、包络线作图法和标准图形参照比较法等。除常规缺陷定量方法外,精确的缺陷定量多采用聚焦探头和各种声成象设备。     

射线照相法的缺陷检出灵敏度

简述射线照相检测方法的缺陷检出灵敏度与对比度和可见度之间关系,射线照相灵敏度与产品透照技术等级、缺陷评定质量级别的关系和重要性。介绍检出缺陷尺寸几个关系式,说明影响检出缺陷灵敏度的主要因素及标准中的几个隐含参量。射线检测人员在实际工作中,在考虑影响因素的同时,可用公式计算结果预计所能达到的检测灵敏度。     

焊缝超声检测灵敏度与检出缺陷的数字定量分析

在对焊缝超声检测检出缺陷数字定量分析的基础上,探讨了在不同检测灵敏度时检出缺陷直径当量的变化,以及不同尺寸对比试块的等效代用方法。为检测人员确定合适的检测灵敏度、等效选用检测对比试块和更直接了解缺陷情况提供参考,也为制定科学合理的检测验收标准提供帮助。     

电站金属材料超声相控阵检测缺陷长度定量研究

针对电站金属材料对接焊缝常见的根部焊接缺陷,设计加工了具有相应模拟缺陷反射体的对比试块,对缺陷长度进行相控阵检测定量研究。结果表明,在一定(满屏的80%)的扫查灵敏度下,采用绝对灵敏度法能较好地实现对缺陷长度的定量测量,并建议选用满屏的50%作为边界阈值进行缺陷长度的定量测量。测量根部未焊透缺陷时,测量误差随着缺陷实际长度的增加而减小,而测量根部裂纹缺陷时,测量误差与缺陷实际长度的变化无明显关系;缺陷高度越大,长度定量测量的正偏差误差越大。     

金属构件缺陷的脉冲涡流近-远场复合定量检测

鉴于脉冲涡流检测和脉冲远场涡流检测在金属构件损伤检测中的优势,提出一种非铁磁性金属构件缺陷的脉冲涡流近-远场复合定量检测探头。通过数值仿真,在系统分析电磁场能流密度的基础上,研究脉冲涡流近-远场检测信号特性及其对构件腐蚀减薄缺陷的响应灵敏度,剖析检测信号特征与缺陷尺寸参数间的关联规律。同时,搭建试验平台,进一步探究基于脉冲涡流近-远场复合定量检测的非铁磁性金属构件腐蚀减薄缺陷定量检测方法。仿真及试验结果表明,所提集成磁场直接和间接耦合分量的新探头构型可同时对金属构件腐蚀减薄缺陷实施脉冲涡流检测和脉冲远场涡流检测,增强了缺陷定量信息的有效拾取。     

全自动超声波检测技术人工反射体的研制

人工模拟缺陷试块是全自动超声波检测技术中的关键组成部分。根据人工反射体(人工模拟缺陷)的研发思路,以及材料的优选、缺陷的定位、焊缝不同部位的缺陷预置,通过人工模拟缺陷来调节全自动超声波检测技术的灵敏度,以求达到提高全自动超声波检测技术的检测精度及检测效率。     

爬波检测技术的应用

对奥氏体不锈钢焊缝和异种金属焊缝表面及近表面缺陷进行爬波检测时,缺陷的定位和定量（测长、测高）是爬波检测的难点。介绍了爬波检测技术的原理、爬波探头和试块。结合大量的试验数据,总结了爬波检测技术应用的具体方法。包括检测系统的标定、灵敏度的设定、缺陷定位以及缺陷定量的详细方法。通过对检测技术的验证,充分证明了爬波检测技术在奥氏体不锈钢焊缝和异种金属焊缝表面及近表面缺陷检测应用中的可靠性。     

Ultrasonic flaw detection of discontinuous defects in magnesium alloy materials

Phased array ultrasonic testing, an effective ultrasonic testing(UT) technology, has been widely used in steel inspection because of its high accuracy, sensitivity, and efficiency. However, as its application in as-cast magnesium alloys has just begun, more research is needed. Considering the important role of the gain compensation in quantifying defects in magnesium alloys by ultrasonic phased array technology, the effects of microstructure, the position, size, and overlap of defects, and boundary distance(distance from the defect position to the side surface of the test casting) on gain compensation of as-cast AZ80 and AZ31 magnesium alloys were studied. Results show the gain compensation increases with the increase of grain size. There is a strict linear positive correlation between gain compensation and defect depth, but such relationship no longer exists due to the defects overlap, orientation and boundary distance. In addition, there is a strict linear negative correlation between the gain compensation and defect size.     

超声波探头回波频率与标称频率误差对锻件探伤结果的影响

计算法是锻件超声波探伤中常用的调整探伤灵敏度和评定缺陷当量大小的方法。如果探头的实际回波频率与标称频率存在误差,将会对探伤灵敏度的调整和缺陷定量的准确性造成影响。为了消除这种影响,需要准确测量探头实际回波频率或使用其它方法调整探伤灵敏度。     

变电站支柱瓷绝缘子超声波检测工艺方法的选择和试验分析

在总结分析传统超声爬波法、横波法、普通直探头法、小角度纵波斜探头法和微型并联爬波法等几种常用的支柱瓷绝缘子超声波检测方法优缺点的基础上，通过试验分析了采用小角度纵波斜探头结合微型并联爬波探头对支柱瓷绝缘子进行超声波检测的工艺方法，确定了用该法对瓷绝缘子进行超声波检测的仪器、探头和试块的选用，探伤灵敏度和扫描速度的调整方法以及缺陷判定的原则。     

国内外钢板超声检测标准对比分析

从适用范围、设备器材、检测条件和方法、对比试块、灵敏度的调校、缺陷的测定与评定等几方面对国内外常用钢板超声检测标准进行对比分析,为有关单位和检验人员更加深入地理解和使用标准,正确执行标准提供参考。     

Effects of geometrical characteristics on defect distributions in alloy components produced by selective laser melting

Selective laser melting (SLM) has been applied to manufacture various alloy components with excellent properties, but its further application is restricted by the intrinsic defects. In this work, the internal defect distributions in samples of three alloys (316L stainless steel, AlSi10Mg and Inconel 718) were investigated respectively, considering the effects of geometrical characteristics of the samples. The defects in the 316L stainless steel sample tend to be formed densely in the central part with large wall thickness, indicating a strong sensitivity to heat accumulation. Contrarily, the Inconel 718 sample shows a higher relative density with homogeneous defect distribution, indicating better formability for the SLM process. For the AlSi10Mg sample, the defect density keeps increasing as the deposition goes on. Typically, the defect density located at sample edges shows an abnormally high level comparing with the inner part, especially in the top sections of AlSi10Mg and Inconel 718 samples. The results are helpful for the geometrical design, the adjustment of building orientation and the further optimization of process parameters in the SLM process.     

加热器碳钢管内插式探头涡流探伤试验

用内插式探头磁化涡流和远场涡流检测技术对８个电厂４８台加热器碳钢管进行了检测,试验结果表明,磁化涡流对碳钢管道孔和内壁缺陷检测灵敏度较高,对外壁缺陷检测灵敏度较低,容易区分内外壁缺陷;远场涡流对碳钢管通孔检测灵敏度较低,地内外壁缺陷检测灵敏度较高,但难以区分内外壁缺陷。     

基于非线性超声的疲劳裂纹检测中二次谐波的激发效率

提出在疲劳裂纹的非线性超声检测中,将二次谐波激发效率作为定量表征疲劳裂纹缺陷的特征参数,并对其理论公式进行了详尽的推导,证明了将二次谐波激发效率作为特征参数对疲劳裂纹缺陷进行定量化是有效的。     

自动化超声波检测钢质圆棒时的灵敏度校准及仿真建模

使用VB6．0语言对在ROB65VIS型自动检测设备下的圆棒类工件超声自动化检测时灵敏度的校准进行了仿真研究。根据超声检测中声波传播过程的特点，提取了其数学模型和主要原理，实现了圆棒类工件自动化超声波检测时灵敏度校准的过程模拟。该研究解决了圆棒类工件灵敏度调节时各类参数较多，计算比较复杂以及自动化检测中由于棒材高速旋转导致灵敏度调节时人工缺陷回波识别困难的问题。仿真模型具有通用性，能对实际检测时灵敏度校准提供理论指导。     

轴瓦超声波检测灵敏度调整方法的探索

从分析巴氏合金轴瓦声学模型着手,揭示超声检测中传统的灵敏度调整方法的不足,通过理论分析找出新的调整方法。     

Quantitative evaluation of die casting surface defect severity by analyzing surface height

It is necessary in factories to assess the severity of the surface defects of castings, as a slight surface defect will be taken as qualified when it brings no bad effect or it can be removed by the subsequent processing. In practical production, professional technicians visually inspect the surface defect severity according to their individual experience. Therefore, it is difficult for them to maintain the same standard and accuracy in the subjective, tedious and labor-intensive work. Recently, image processing techniques based on optical images have been applied to achieve better accuracy and high efficiency. Unfortunately, optical images cannot directly quantify surface depth, which works as a crucial factor in the practical assessment of surface defect severity. The surface roughness evaluation algorithm, which takes into account of both area and depth information of the assessed surface, was applied to directly characterize surface defect severity based on surface asperity rather than optical image. The results using standard casting pieces show that surface defect severity has no apparent dependence on surface roughness. However, the subsequent results show that the root-mean-squared-deviation (RMSD) of surface gradient of flow line defects positively correlates with the increase of defect severity. The other types of defect do not present such tendency. Thus, practical workpieces with flow line defects on the surface were used to verify the universality of this tendency. The results show that surface roughness of an unqualified workpiece is larger than that of a qualified workpiece after surface slope adjustment, but presents no obvious coincidence before the adjustment. In contrast, the RMSD of an unqualified workpiece, no matter before or after the adjustment, is larger than that of a qualified one.