HOT SALT CRACKING OF TI ALLOYS

Hot salt cracking of Ti alloys has been investigated by examining the reaction of hot Cl2 with some α phase alloys: Ti-5Al-2·5Sn and binary alloys of Ti-Al and Ti-Sn. Cl2 can cause intergranular cracking in bulk specimens of the alloys if only a narrow, highly strained region is exposed. Thin foil electron microscope experiments have shown that Cl2 preferentially attacks dislocation lines and grain boundaries in the susceptible alloys. The solute elements segregated to these regions stimulate the formation of Ti Cl2 which is probably the main corrosion reaction. The role of O2 and moisture both in crack initiation and propagation is briefly considered. © 1968 Pergamon Press Ltd.