The mechano-chemical effect in a group of five die cast and extruded magnesium alloys has been investigated. Corrosion rates were determined as a function of both the processing conditions, used to produce the alloys, and the applied tensile strain by means of potentiodynamic polarisation measurements and immersion tests. These were conducted at 25 degrees C in several borate buffer solutions containing NaCl, Mg(OH)(2) or NaOH. In order to understand the reason for the advantages of AM50 Alloy under stress corrosion, TEM analysis were performed. This analysis revealed the location of dislocation pile-ups at a further stage in the stressed AM50 alloy which were found to be beneficial to it is resistance to stress-corrosion cracking. It is shown that the mechano-chemical effect is strongly dependent on the aluminium content in the alloy. (c) 2006 Elsevier Ltd. All rights reserved.