A Method for Ultrasonic Nondestructive Evaluation of Internal Residual Stress Level of Aluminum Alloy Forgings

Abstract

The invention belongs to the field of nondestructive detection and relates to a method for nondestructive evaluation of residual stress levels in an aluminum alloy forged piece through ultrasonic waves. According to the method, the phenomenon that the propagation speed of the ultrasonic waves in materials can be affected by stress in the materials to a certain extent is used, and the difference of residual stress levels among different positions in the large size aluminum alloy forged piece is reflected through changes of sound speeds. The method has the advantages of being high in detection speed, large in measuring depth, good in economy and the like. The residual stress in the large size aluminum alloy forged piece is measured through the sound elastic effect of the ultrasonic waves in the method, and the method has the advantages of being high in measuring speed, convenient to use, flexible in measuring range, good in economy and the like. The single-time measuring time of the method is about five minutes and is shorter that the single-time measuring time of a neutron diffraction residual stress measuring method, the detection speed is high, the maximum measuring depth of the method can reach 400 mm, is larger that the measuring depth of the neutron diffraction method, and is much larger that the measuring depth of an X-ray method or a Barkhausen noise method.

Description

technical field [0001] The invention belongs to the field of non-destructive testing and relates to a method for ultrasonic non-destructive evaluation of the internal residual stress level of aluminum alloy forgings. Background technique [0002] In order to meet the requirements of mechanical properties, large aluminum alloy forgings need to be treated with solid solution and aging. During the solid solution process, due to the large size of the forgings, there is a large difference in the cooling rate of each part during the rapid cooling process, resulting in different Uniform shrinkage deformation brings large residual stress. Although residual stress can be eliminated to a certain extent by processes such as cold pressing, pre-stretching, and aging, the effect of these processes on residual stress is related to the initial residual stress level, and different residual stress states require different elimination processes. However, due to the lack of a means of non-dest...

AI Technical Summary

Problems solved by technology

However, due to the lack of a means of non-destructive measurement of residual stress during the solid solution process, the existing residual stress relief process lacks a reference basis and the residual stress relief is insufficient, which in turn causes large aluminum alloy forgings to appear unsatisfactory in subsequent processing. Deformation of rules affects product qualification rate

[0003] The traditional methods of non-destructive evaluation of residual stress are mainly X-ray method and Barkhausen noise method, but their penetration depth is relatively shallow. The depth does not exceed 0.3mm

The cause of irregular deformation during processing is mainly the residual stress inside the forging, which can only be measured by neutron diffraction at present, but this method requires huge equipment investment and the cost is too high