Precipitation and mechanical properties characterization of Al-Cu-Mg aluminum alloys based on laser ultrasound

The precipitation has an important influence on the mechanical properties of Al-Cu-Mg alloy. However, the metallographic and mechanical properties testing methods are not only time-consuming and laborious but also have a small detection area nowadays. In this paper, the laser ultrasonic non-contact detection technology is adopted, and the Al-Cu-Mg alloy rolled sheet with more precipitation is selected as the research object. The microstructure and mechanical properties of the standard samples were detected by scanning electron microscopy, electron backscatter diffraction and tensile test. Ultrasonic attenuation coefficient and sound velocity were obtained by laser ultrasonic test and Variational Modal Decomposition (VMD) method. The results show that, with the increase of solution temperature and solution time, the hard precipitate phase around the aluminum matrix gradually dissolves into it, and the solid solution strengthening is improved; at 500 degrees C and 360 min solution aging, the attenuation coefficient and sound velocity of ultrasound waves change abruptly, and it is judged that the precipitation phase and grain size are abnormal; the characteristics of ultrasonic signals and yield strength have a moderately good correlation with microhardness, and the yield strength and microhardness can be characterized by attenuation coefficient and sound velocity. This provides a new method for non-contact online inspection of Al-Cu-Mg aluminum alloys.