Austenite Transformation in Duplex Stainless Steels under Fast Cooling Rates




Abstract: Duplex Stainless Steels when submitted to heating, can have its good properties impaired since it is strongly dependent on the austenite-ferrite phase ratio. In a welded joint, the transformation kinetics at the heat affected zone (HAZ) is a function of the cooling rates applied which in turn are dependent on the heat input. The HAZ is usually ferritized at these temperatures, and it has been argued that small variations of the chemical composition can play a role in the solid state transformation sequence of ferrite to austenite during cooling. The δ → γ transformation has been reported to be massive and diffusionless due to the fast cooling rate, but it is also considered a diffusion controlled transformation. The aim of this work is to evaluate the effect of different heat inputs on the HAZ of two duplex stainless steels UNS S32304 and S32750, obtained by physical simulation.

Authors: L.O. Luengas, E.V. Morales, L.F.G. de Souza, and I.S. Bott

Keywords: Duplex Stainless Steels, heat affected zone (HAZ), δ → γ transformation

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8 pages


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