The initiation and propagation of chloride-induced transgranular stress-corrosion cracking (TGSCC) of 304L austenitic stainless steel under atmospheric conditions

Bending tests were used to investigate the stress-corrosion cracking of 304L stainless steel in a corrosive atmosphere containing magnesium chloride. Initially smooth specimens showed multiple closely spaced cracks after exposures of up to 500 h. These showed threshold stresses of 10 MPa and a threshold humidity of 30%. Cracking rates increased with stress but were a maximum at plastic strains of 2%. Examination of cracks using focussed ion beam milling and electron diffraction indicated a multi-stage mechanism of propagation via preferential oxidation of slip planes. The apparent activation energy was 34 kJ mol(-1) in the temperature range 333-363 K. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.