Comparison of the formability of austenitic reversion-treated and temper-rolled 17Cr-7Ni steels

Abstract

Microstructures, mechanical properties and formability of austenitic 17Cr-7Ni AISI 301 (EN 1.4310) and 301LN (EN 1.4318) type steels strengthened by either reversion treatment or temper rolling were studied. The reversion treatments were carried out for 53% cold-rolled 301LN steel sheets using a 600 kW pilot induction heating line and commercial 10- 20% temper-rolled sheets were adopted for the reference material. X-ray diffraction was employed to determine the phase fractions and electron backscatter diffraction for estimating the grain size and distribution. Mechanical properties were determined using tensile tests and the stretch formability by Erichsen cupping tests. The yield strength of the studied structures varied in the range of 495-1100 MPa. The stretch formability was found to be related to the tensile yield strength and uniform elongation and it was at least equal or slightly better for the reversion-treated ultrafine-grained specimens than for the temper-rolled counterparts on the same yield strength level. The contribution of the formation of deformation-induced martensite for uniform elongation and stretch formability is discussed.