Effect of strain paths gutierrez et al

EXPERIMENTAL PROCEDURE D. Gutirrez1, A. Lara1, D. Casellas1 and J.M. Prado1,2 1CTM-Centre Tecnolgic, Av. Bases de Manresa, 1, 08240 Manresa, Barcelona, Spain2Department of Materials Science and Metallurgical Engineering, ETSEIB, Universitat Politcnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spaindavid.gutierrez@ctm.com.es, toni.lara@ctm.com.es, daniel.casellas@ctm.com.es, jm.prado@ctm.com.esRESULTS AND DISCUSSIONCONCLUSIONSINTRODUCTIONEffect of Strain Paths on Formability Evaluation of TRIP steelsACKNOWLEGMENTSUsed to understand sheet metal formabilityForming Limit Curve (FLC)

Obtained by diferent linear strain paths (2/1) Parameters affect FLC

Strain hardening exponentPlastic anisotropyStrain pathsModification of FLC by changes in strain paths (Graf and Hosford, 1994)

Nakajima Test

Marciniak Test

Sample geometries

Strain measurement: Stochastic pattern GOM/ARAMIS

Testing device: Double acting press

Materials TRIP800 2.0mm DC03 1.5mm

Mathemathical method:ISO standardBragard modified methodThe authors acknowledge financial support from the Spanish Ministerio de Industria, Turismo y Comercio (Programa de Proyectos Consorciados, FIT 170300-2007-1) and from Generalitat of Catalonia Departament dInnovaci Universitats i Empresa for the FIE financial support.

FLCs are influenced by mathematical method used to calculate them. Bragard method more conservative.Influence of mathematical method

Influence of stretching test:Bigger differences in TRIP steel, especially in FLD0 and biaxial tension areas.Marciniak test more linear strain paths, especially in FLD0.DC03 different strain paths, but similar FLCs.The different strain paths provides differences FLCs with Nakajima and Marciniak tests.TRIP800 steel have more differences in FLCs than DC03.The strain paths affect more in AHSS steel, it could be an explanation why FLC are not valid in these steels.