Static Softening Behaviour in High Aluminum Steels

05 Aug 2011

S.V. Parker; Tata Steel RD&T Swinden Technology Centre, United Kingdom
Z. Aretxabaleta, B. Pereda, B. Lopez; CEIT and TECNUN, Spain

The effect of Al addition on the static softening behavior of C-Mn steels was investigated. The compositions of the steels studied are representative of the recently developed TRIP-assisted steels: a base composition of 0.2%C, 2%Mn, 50ppm N and three different Al levels, 0.03 (base steel), 1 and 2%. Double-hit torsion tests were performed at different deformation temperatures, in the range 950ºC to 1100ºC, and pass-strains,  =0.2 and 0.35. It was found that solute Al produced a significant retardation on static recrystallization kinetics, equivalent to that exerted by 0.026%Nb for the 1%Al steel and to 0.05%Nb for the 2%Al steel. Additionally, at the lowest temperatures (950-1000ºC) and 2%Al level, austenite to ferrite phase transformation was found to be concurrent with softening, enhancing retardation in the mechanical softening.

Paper presented at Thermec 2011, Quebec, Canada, August 1-5, 2011