Creep behaviour of Fe–Mn–Al steel from 500 to 800 °C : Part 1: Analysis of constant-load creep data

Abstract

The creep properties of an Fe–34.5Mn–9.2Al–1.8Si–0.95 (wt.%) alloy were determined by constant-load tests at four temperature levels ranging from 500 to 800 °C and stresses from 30 to 560 MPa. Correlations among stress, temperature, secondary creep rate, rupture time and creep ductility were obtained and results are compared to literature data. Parameters of the Norton, Arrhenius and Monkman–Grant relations are discussed as an attempt to gain some understanding on the mechanisms controlling creep behaviour of the material in the stress/temperature range investigated. The investigated alloy exhibited potential creep law with n values ranging mainly from 3 to 5 and an m value of the Monkman–Grant relation close to 1. The apparent activation energy, in the temperature range of 600 to 800 °C, takes values of 376 ± 38 kJ/mol. Microstructural instability was observed in crept samples, mainly from 500 to 600 °C, which was associated with the lower creep ductility observed in this temperature range.