Hot Deformation Behaviour of Low Alloyed Steel

Abstract:

Hot deformation of a continuously cast low alloyed steel is studied by means of hot compression and tensile tests carried out after austenitization between 700–790 °C at 3x10^-4 – 0.3 s^-1 of strain rate. The ferrite transformation at the applied cooling rate was determined at 710°C by means of dilatometry. The compressive flow data obtained by using a Gleeble®1500 machine are evaluated to obtain the strain rate sensitivity and the processing maps using different models. The tensile data are used to determine the ductility of the material with different deformation parameters. A new calculation method is used for the instability parameter derived from the dynamic materials model. The strain rate sensitivity does not predict any instability but all the others instability parameters do, including the new one. Pores are formed at the prior austenitic grain boundaries at low strain rates, causing a decay of ductility in the tensile samples. A minimum in the ductility was observed for low strain rates at 750°C. Low strain rates and low temperatures increase the formation of more ferrite than without deformation at the corresponding heat treatments without deformation. In these conditions, the deformation is concentrated in the softer ferrite phase. Low power efficiency was calculated at high strain rates, where no dynamic recrystallization takes place. The domains with similar efficiency of power dissipation are correlated to deformation induced ferrite formation and ferrite recovery. These domains vary with the increasing strain.

• Periodical: Materials Science Forum (Volumes 706-709)
• Pages: 2794-2799
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.706-709.2794
• Online since: January 2012
• Authors: Maria Cecilia Poletti, S. Großeiber, Sergiu Ilie, Hans Peter Degischer
• Keywords: Deformation Induced Ferrite, Ductility, Low Alloy Steel, Processing Map

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