The TC4 alloy used in the experiment was forged in the […]
The TC4 alloy used in the experiment was forged in the β single-phase region and then rolled into a 70 mm thick plate in the α+β two-phase region. The microstructure obtained after annealing was a typical equiaxed structure. The titanium alloy thick plate was ultrasonically detected in the thickness direction, and the wave pattern used was a longitudinal wave with a frequency of 5 MHz. The artificial defect of the comparative test piece was a flat bottom hole with a diameter of 1.2 mm. The microstructure was sampled from two locations with different levels of ultrasonic flaw detection, and the sampling size was 20 mm × 20 mm × 70 mm (plate thickness). Among them, 1 test block detection clutter level is Φ1.2mm-12dB, 2 test block is Φ1.2mm-4~-5dB, and detection block clutter is -12dB. By detecting the location of the clutter, the high clutter region of the two test blocks appears at the intermediate thickness of the test block. In order to study the effect of microstructure on the level of ultrasonic flaw detection, the microstructure of the two different levels of the clutter was observed under the optical microscope under the optical microscope, and the middle of the test block was observed. Microstructure of the area near the thickness. The two test blocks are sliced perpendicular to the thickness direction, wherein the distance between the adjacent slice observation faces in the thickness region of the test block is about 1.5 mm, and the distance between the adjacent slice observation faces at both ends of the test block is about 4 mm. 1 The whole test piece is sampled in layers, and the spacing between adjacent slice observation surfaces is 6mm. Orientation analysis of typical regional microstructures was performed using scanning electron microscope backscatter diffraction (EBSD) techniques.