Effect of strain paths gutierrez et al
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EXPERIMENTAL PROCEDURE D. Gutiérrez 1 , A. Lara 1 , D. Casellas 1 and J.M. Prado 1,2 1 CTM-Centre Tecnològic, Av. Bases de Manresa, 1, 08240 Manresa, Barcelona, Spain 2 Department of Materials Science and Metallurgical Engineering, ETSEIB, Universitat Politècnica de Catalunya, Av. Diagonal 647, 08028 Barcelona, Spain [email protected], [email protected], [email protected], [email protected] RESULTS AND DISCUSSION CONCLUSIONS INTRODUCTION Effect of Strain Paths on Formability Evaluation of TRIP steels ACKNOWLEGMENTS Used to understand sheet metal formability Forming Limit Curve (FLC) Obtained by diferent linear strain paths (ε 2 /ε 1 ) Parameters affect FLC Strain hardening exponent Plastic anisotropy Strain paths Modification of FLC by changes in strain paths (Graf and Hosford, 1994) Optical system GOM/ARAMIS Light Top piston. Maximum force (1500 kN) Bottom piston. Maximum force (500 kN) Sample Nakajima Test Marciniak Test Sample geometries Strain measurement: Stochastic pattern GOM/ARAMIS Testing device: Double acting press %C %Si %Mn %Cr %Ni Al% %Nb TRIP800 0.201 1.614 1.729 0.024 0.032 0.042 0.010 DC03 0.078 0.010 0.294 0.016 0.031 0.036 0.009 Materials TRIP800 2.0mm DC03 1.5mm Yield Stress [MPa] Ultimate Tensile Stress [MPa] Strain [%] n-value r-value TRIP800 546 835 32.0 0.22 0.99 DC03 185 313 35.1 0.21 1.58 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 -0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,5 0,6 ε 2 ε 1 DC03 FLC Points NAK ISO DC03 FLC NAK ISO DC03 FLC Points NAK BRG DC03 FLC NAK BRG TRIP800 FLC Points NAK ISO TRIP800 FLC NAK ISO TRIP800 FLC Points NAK BRG TRIP800 FLC NAK BRG Mathemathical method: ISO standard Bragard modified method 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 -0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 ε 2 ε 1 DC03 FLC Points NAK BRG DC03 FLC NAK BRG DC03 FLC Points MAR BRG DC03 FLC MAR BRG TRIP800 FLC Points NAK BRG TRIP800 FLC NAK BRG TRIP800 FLC Points MAR BRG TRIP800 FLC MAR BRG TRIP800 2.0mm 0,0 0,1 0,2 0,3 0,4 0,5 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4 ε 2 ε 1 MARCINIAK NAKAJIMA DC03 1.5mm 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 -0,4 -0,3 -0,2 -0,1 0,0 0,1 0,2 0,3 0,4 0,5 0,6 ε 2 ε 1 MARCINIAK NAKAJIMA DC03 1.5mm 0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 -0,9 -0,7 -0,5 -0,3 -0,1 0,1 0,3 0,5 0,7 0,9 1,1 ε 2 /ε 1 ε 1 MARCINIAK NAKAJIMA TRIP800 2.0mm 0,0 0,1 0,2 0,3 0,4 0,5 -0,6 -0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 ε 2 /ε 1 ε 1 MARCINIAK NAKAJIMA The 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 d’Innovació 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 FLD 0 and biaxial tension areas. Marciniak test more linear strain paths, especially in FLD 0 . 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.
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Transcript of Effect of strain paths gutierrez et al
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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, [email protected], [email protected], [email protected], [email protected] 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.
