Strain Localization Behavior of Cold-Rolled Deep-Drawing Steels

Abstract

With the purpose of defining optimal microstructure and texture for higher quality in deep–drawing operations of cold-rolled steels; this study monitors and analyses the micro- and macro-scale deformation behavior of DC04 grade cold-rolled steel sheets under uniaxial tension and biaxial stretching. An in-plane biaxial test setup capable of observing and measuring the deformation is utilized for obtaining strain maps at the micro- and macro-scale. Strain maps at the micro-scale are then compared with texture and microstructure data obtained before and after the deformation. Results show strain localization to the interior of grains under both strain paths, as opposed to the common grain boundary localization observed in the literature. Remnants of the α fiber components in the initial γ fiber texture, especially grains with {100}<110> orientations, are the likely sources of the localizations as they allow deformation in the sheet thickness direction. While these localizations do not appear to be critical for macro-scale formability, their suppression should be helpful in preventing surface defects and local fracture. Total elimination of α fiber components from the initial texture is proposed as a way preventing micro-scale localizations