关键词: 铝合金厚板, 三轴张应力, 沿晶开裂, 快速剪切

Abstract: The fracture mechanism of notched round bears and notched plane strain tension specimens of LC4 aluminum alloy plate have been investigated in this study. It was found that under high enough triaxial tensile stress intergranular splitting always appeared first. As soon as the splitting plane grew to a critical size, fast shear along short transverse direction of the plate followed locally just in its vici-nitv. Propagation of this kind oi shear lead the, specimens to a catastrophic iailure. The extent of intergranular splitting as well as the scale of local last shear within its vicinity depend mainly on the value oi triaxial tensile stress pramerer (σm/σ). Different heat-treatments have also some effect on intergranuler splitting but did not change the macroscopic modes and the microscopic characteristics of fracture.

Key words: aluminium plate, triaxial tensile stress, intergranular splitting. fast shear.