The Effect of Cooling Rate on the Damage Micromechanisms of DP Steels

Orlando León-García; Roumen H. Petrov; Leo A.I. Kestens

doi:10.4028/www.scientific.net/MSF.638-642.3337

Paper Titles

Effects of Manganese Content and Heat Treatment Condition on Mechanical Properties and Microstructures of Fine-Grained Low Carbon TRIP-Aided Steels
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First-Principles Calculations and the Thermodynamics of Cementite
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Calculation of Stress-Strain Curve of Two-Phase Microstructure on the Basis of the Extended Secant Method
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Modeling of Phase Transformation and Carbon Behaviors after Holding at γ/α Region and Controlled Cooling in Low Carbon Steels
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The Effect of Cooling Rate on the Damage Micromechanisms of DP Steels
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A View on the Strategy in the Processing of Hot Rolled Dual Phase Steels
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Effect of Coiling Temperature on Microstructure and Mechanical Properties of a Nb-V Microalloyed Steel
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A Study of the Carbides in High-Speed Steel Rolls
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Ductility of Microalloyed Steels during Hot Deformation
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HomeMaterials Science ForumMaterials Science Forum Vols. 638-642The Effect of Cooling Rate on the Damage...

The Effect of Cooling Rate on the Damage Micromechanisms of DP Steels

Abstract:

The microstructural failure mechanisms of two DP steel sheets cooled with different cooling rates during their heat treatment are compared in the present study. The as-cold rolled DP steel sheets were annealed at intercritical temperature and cooled down with rates of 45°C/s (quenching) and 2 °C/s (slow cooling). Uniaxial tensile tests were carried out on samples from both sheets and the microstructure of undeformed samples and the broken tensile specimens was evaluated by optical microscopy, scanning electron microscopy and electron back-scatter diffraction technique. Although the grain size did not show significant differences, the amount and size of the constituents, e.g. martensite and bainite, differ between both alloys. Concerning the mechanical properties, the quenched material showed superior strength and ductility besides a less localized deformation at higher strains. The area fraction of voids in the broken specimens was low for both steels. In the slow cooled samples the nucleation of shear bands was on the large voids and cracks were observed along these shears bands. It was concluded that the detrimental effect of void nucleation on both steels is not only attributed to their null-carry capacity but more to the stress concentration close to the voids which gives rise to strain localization in the form of shear bands.