Damage activity recognition and behaviour of 40CrNiMoA steel under stretching using Acoustic emission technique

Railway axles are very common structures and the most important components used in high-speed transport fields, such as high-speed railway and subway. However, as parts of vehicles run during the serving time, the biggest failure mostly comes from axles. For this reason, it is of vital importance to detect the original cracks existing in railway axles and to recognize the damage severity or activeness of railway axles because the initial cracks are usually not easy to detect and know. Acoustic emission (AE) method is one of the most widely used ultrasonic techniques for monitoring crack growth and structure activities. In this paper, AE technique is used to analyze and evaluate different damage growing stages of 40CrNiMoA steel in process of stretching. Parameter-based approach was used to describe AE signal and the process of stretching. Then, the regulation between AE signal and crack growth was obtained by comparing AE parameters and stress-strain diagram of 40CrNiMoA steel.