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机车车辆重要零部件的运行安全性的高低是根据其材料中是否存在诸如裂纹、缩孔等宏观金属缺陷来判断的。通常,借助于传统的无损检验方法可发现此类宏观缺陷,但一些基本因素即并未被考虑,比如在运用中的侧架金属材料中所发生的微观缺陷的发展过程。这些微观缺陷潜伏时间的长短是不知道的,也不可能由传统的探伤方法来确定。本文的目的就是要研发一种超声波方法来评估货车转向架侧架金属在缺陷发展前期的状态。金属损伤积累到形成明显的裂纹(缺陷发展前的状态,或者破坏前的状态)会使金属的组织特性发生许多改变。物理声学特性对这些改变非常敏感。本文旨在介绍研制开发出一种技术检验方法。该检验方法就是要对累积的运用损伤用测量计算装置来进行探测。文中提出了用表征侧架各点上测得的弹性波速度比值作为指标。其中,弹性波的速度值由声波从发射器到接收器之间的时间来确定。同时,检验还使用了专门的具有温度补偿的分离-合并转换器,这种转换器可保证传播延时时间的测量绝对误差值处于±2 ns。文中描述了就侧架金属试样(20ГЛ铸钢)进行了机械试验和表面波探测。试验表明,在接近损坏前状态的金属内,声波速度相对于原始速度会下降2%。由直接从经过不同运用期限的侧架上获得的试验数据证明了了声学检验法对金属缺陷前状态有很高的敏感性。显然,文中所列出的声学数据非常客观地反映了运用损伤累积这样的事实,而且这些数据资料也能解决环境条件很苛刻的诊断任务。此外,所提出的评估侧架金属状态的方法的可靠性可借助测量手段而得到保证,故已可以将其应用于实践中。
Locomotives and important components of the operational safety level is based on the material in the presence of such as cracks, shrinkage and other macro-metal defects to judge. Often, such macroscopic defects are found by means of conventional non-destructive testing methods, but some fundamental factors are not considered, such as the development of microscopic defects occurring in the side-frame metallic materials in use. The latency of these microscopic defects is unknown and can not be determined by conventional methods. The purpose of this paper is to develop an ultrasonic method to assess the condition of the metal of the truck bogie side frame during the early development of the defect. Accumulation of metal damage to the formation of significant cracks (pre-defect state, or pre-failure state) will result in many changes in the microstructure and properties of the metal. Physical acoustics are very sensitive to these changes. This article aims to introduce the research and development of a technical test methods. The test method is to use the cumulative damage calculation using a measuring device to detect. In this paper, we propose to use the elastic wave velocity ratio measured at each point of the side frame as an index. The speed of the elastic wave is determined by the time it takes for the sound wave to travel from the transmitter to the receiver. At the same time, the test also uses a dedicated temperature compensation with separate - merge converter, this converter can guarantee the propagation delay time measurement of absolute error value in ± 2 ns. The article described the mechanical test and surface wave detection of side frame metal specimens (20ГЛ cast steel). Experiments show that in the near-pre-damaged state of the metal, the acoustic velocity relative to the original speed will drop 2%. The experimental data obtained directly from the side frame over different service life periods demonstrate the high sensitivity of the acoustic test to the pre-metal defects. Obviously, the acoustical data listed in this article reflect the fact that damage accumulation is very objectively applied, and these data can also solve the diagnostic tasks with harsh environmental conditions. In addition, the proposed method of evaluating the side frame metal’s reliability can be guaranteed by means of measurement, so that it can already be put into practice.