Methods for Estimating the Actual Size of Defects Based on the Lengths of Their Frontal Images

Purpose of research. The present paper concerns the close analysis of detecting the sizes of defects and ways of their identification. The aim is to solve the problem of rational choice of equipment, which will make it possible to fully, clearly and reliably judge the quality of the product. This is important because, depending on the material of the product, the resulting defect sizes may vary. Methods. For this purpose, this article discusses a method for determining the actual size of defects’ images in ultrasonic control of export oil pump cases made of 20GL steel grade using a flaw detector with digital-focused antenna arrays. The paper describes the main differences in the configuration of equipment that uses different techniques of image restoration, and the feasibility of applying multi-channel sensors for the control of this type parts. The design of the antenna array and phased antenna array has been considered as well as the principle of operation of sensors with phased array antenna and digital phased array antenna. The study of the cast body of export oil pump has been completed, during which defects such as “microporosity” was found. There have been identified their maximum permissible front distances and the formula to determine their actual size has been deduced. The dependence of frontal sizes of defect images on the depth of their occurrence in the product has been considered. Results. According to the obtained data, a graph of dependence of the frontal size of a defect image on the depth of occurrence has been constructed. Using this graph, it is possible to determine the maximum permissible sizes of defect images for intermiary depth, excluding calculations, which confirms the economic efficiency in the analysis of the control results using this method. Conclusion. The authors substantiate the feasibility of using equipment with phased array antenna and digital phased array antenna.