The Deformation Measurements of Portevin-Le Chatelier Shear Bands in Al-Cu Alloys
Al-4%Cu合金中锯齿形屈服剪切带的变形测量

A series of white light speckle patterns was continually recorded by high-speed CCD (1000 fps) during the formation of type B serrated yielding (PLC) shear band in tensile tests of Al-4%Cu alloy. With the image analysis technology of digital speckle correlation method, the displacement and strain spatial distribution of PLC shear band were quantitatively obtained, and the evolution process of PLC shear band with time was reproduced. The results clearly prove an evolution mechanism of type B PLC shear bands, that is, a PLC shear band first nucleates at one side of specimen, then transversely runs through the entire specimen section with a certain angle, finally forms an inhomogeneous deformation bands. The experimental results show that there exists elastic shrinkage deformation outside the band during the formation of PLC shear band.