A Finite Element Analysis on a Localized Deformation Band Moved in Thin Specimens Made of SUS304 by Nonlocality and Dynamic Strain Aging

Abstract

During tensile tests at room temperature using thin specimens made of SUS304, the propagation of X-shaped strain localization with serrations in flow stress occurs in the later stage of deformation. As a mechanism of the phenomenon, it can be considered that the necking in this material can be strengthened by strain-induced martensitic transformation (SIMT). On the other hand, the mechanism of the phenomenon can be dynamic strain aging (DSA) which cause the similar phenomenon called Portevin-Le Chatelier (PLC) band observed frequently in the aluminum alloys. That is, the mechanism has not been fully-concluded. In the past, it is reported that the propagation of strain localization bands can be generated by nonlocality of deformation in order to represent local necking and size effects of the specimen accurately. The analysis with nonlocality is quite hard to express the propagation of X-shaped strain localization with serrations. In another previous study, the model of DSA is introduced into the stress-strain, strain rate, temperature relationship for either austenite or martensite phase and that the propagation of X-shaped strain localization and serrations is confirmed. In the analysis which introduce the DSA, a use of value for the coefficient parameter n might be incorrect. Therefore, it can be said hardly that the analysis can express proper phenomena. The purpose of this study is to elucidate the mechanism of the phenomenon. The analysis considering the nonlocality with the damage or DSA solely with different value of parameter n are done by including them into the finite element method. Then, all the results including experimental ones are compared.