Ultrasonic testing in large annular forgings

2024-08-14 15:45:56

The main challenge in ultrasonic testing of large annular forgings is to consider both detection sensitivity and detection blind spots. The detection sensitivity of forgings at different depths needs to meet the technical requirements, and the detection blind spot on the surface of forgings should be smaller than the machining allowance. However, both factors need to be considered simultaneously, which is difficult. The surface blind spot of ultrasonic testing increases with the increase of the initial wave width of the flaw detector, and the initial wave width increases with the increase of sensitivity. For large-sized (300mm~400mm) forgings, when the ultrasonic testing reaches the equivalent of a 1.2mm flat bottom hole, the initial wave width has already reached tens to hundreds of millimeters, making it difficult to meet the requirement of machining allowance of several millimeters. Therefore, it is difficult to achieve the requirement of balancing sensitivity and detection blind spots through a single inspection in the testing of large-sized forgings.

It is possible to consider dividing the detection of large-sized forgings into zones based on depth, that is, while meeting the requirements of surface blind spots, measuring the combined performance of the instrument and probe, and using the * * large detection depth that can meet the detection sensitivity requirements as the surface zone. To ensure that the detection of the surface zone meets the requirements of detection sensitivity and blind spots, it is necessary to make the reflection wave height of the flat bottom hole buried at a depth equal to the machining allowance and the * * large depth of the surface zone reach the reference wave height. The area below the surface is referred to as the depth zone. In order to ensure that the detection of the depth zone meets the requirements of detection sensitivity and blind spots, it is necessary to make the reflected wave of the flat bottomed hole with a burial depth equal to the depth zone and the surface zone * * large depth reach the reference wave height.

Solve the ultrasonic testing problem of large-sized and complex forgings according to the above ideas for large annular forgings. Considering that the water immersion method has better detection blind spots than the contact method and is insensitive to the surface roughness and shape of forgings, the water immersion method can be chosen to detect the surface area; The sensitivity of the contact method is better than that of the water immersion method. It is possible to consider using either the contact method or the water immersion method to improve sensitivity for detecting depth zones. Depending on the specific situation, a combination of water immersion and contact methods can be selected for detection while meeting sensitivity and blind spots requirements.