Measurement of local strain induced martensitic phase transformation by micro hardness
Shibutani Yoji; Taniyama Akinori; Tomita Yoshihiro; Adachi Taiji
Abstract:By the duplex effect produced by two kinds of phases of austenite and martensite, the transformation induced plasticity (TRIP) steel is improved in ductility and fracture toughness. The strain induced martensitic phase transformation could be associated with the strain localization behavior. Accordingly, the measurement of the amount of local transformation is necessary in order to construct a more physical evolution model in the constitutive equation. In this study, a new measurement system using a micro hardness tester is proposed to obtain a volume fraction map of the martensitic phase expanding in the neighbor of strain localization. Then the system is applied to investigate the inhomogeneous transformation behavior around the notch root of SUS304 stainless steel bar under uniaxial tension. Key Words:strain-induced martensitic phase transformation, micro-hardness, volume fraction, SUS304 stainless steel, notched bar