Study on Microstructure and Properties of TC4 Sheets with Different Rolling Thickness

Inhalt:
The microstructure and mechanical properties of TC4 sheet with different thickness were studied by metallographic microscope, tensile property test and fracture morphology analysis. The results show that the metallographic structure of the four kinds of plates is dominated by α+β phase, and the morphology of α phase is not uniform and unevenly distributed in the microstructure, and there is a large strip α phase in the transverse microstructure of the 2 mm thick plate. In the transverse and longitudinal structure of the sheet, there is a strip structure with alternating large and small grains, and the α grains are elongated directionally. The strength of sheet metal increases with the increase of thickness, while the plasticity is opposite to the strength. The 2 mm thick sheet has the largest strength value, Rm is 1056 MPa and Rp0.2 is 997 MPa. The maximum plasticity value is obtained when the thickness of the sheet is 0.8 mm, and its A value is 19.5%. The microfracture morphology of the plates with different thickness is similar, and they are mainly dimples, which are equiaxed dimples, and have obvious ductile fracture characteristics. In addition to the dimple morphology, the fracture morphology of 2 mm thick plate is composed of many small planes, and there are a large number of especially fine microcracks in the dimple.