アルミニウム合金の高温引張変形挙動の画像相関法による評価

抄録

Deformation behaviors of aluminum alloy A3003 under constant high temperature and under cooling from high temperature were precisely evaluated by digital image correlation (DIC) method. Tensile testing system equipped with a furnace which can control heating and cooling at an arbitrary rate was developed. DIC analysis for 3D deformation of necked region in tensile specimen enabled evaluation of the true stress-true strain curves. True stress-true strain curves under constant temperature were accurately described by constitutive equations which express the logarithm of true stress as the function of the squared logarithm of true strain. FEM analysis of the tensile test revealed that the stress distribution in the localized necking region became non-uniform when the strain exceeded 0.1. Therefore, it is considered that the true constitutive equation of the material cannot be obtained only from the stress-strain curve defined by the surface deformation and strain measured by DIC method. Under cooling from high temperature, higher resistance was measured than that predicted from true stress-true strain curves under constant temperature. It was suggested that consideration for time-dependency of true stress-true strain curves is necessary for precise simulation of residual stresses and strains on casting and multi-material joining processes.