Rèn hợp kim titanđược sử dụng rộng rãi trong lĩnh vực hàng không vũ trụ do mật độ thấp, khả năng chịu nhiệt độ cao, chống ăn mòn và các đặc tính không - từ tính.
Titanium alloys are non-magnetic materials, so the conventional methods for non-destructive testing of titanium alloys can only be the following: ultrasonic testing, penetrant testing, and radiographic testing. At the same time, since the defects of titanium alloy forgings are mainly cracks, voids, and uneven overheating of the structure, let us focus our attention on how to use ultrasonic testing to find cracks and voids.
1. Detection of cracks in titanium forgings
According to the aviation inspection standards (BMS, BAC, QAS, OCTI, etc.), calibrate the ultrasonic instrument and select the appropriate oblique probe. The internal grain of titanium alloy material is fine and there is less clutter, so the oblique probe only needs to slide zigzag from two sides. The couplant should be glycerin to minimize the influence of the coupling between the probe and the workpiece. The cracks (discontinuities) may not be detected by ultrasonic waves. In this case, eddy current testing and penetrant testing are needed for auxiliary inspection.
2. Detection of voids in titanium forgings
The detection standard is the same as the crack detection standard. In this case, a straight probe (single-straight and double-straight) is required to detect void defects. In the detection of straight probes, the following parameters are mainly concerned: bottom wave height and loss, defect echo height (equivalent size), defect depth, area, etc. For particularly tiny voids, straight probes may not be able to detect them, and angled probes may be used to detect them if necessary.
