Damage resistance in gum metal through cold work-induced microstructural heterogeneity

TitleDamage resistance in gum metal through cold work-induced microstructural heterogeneity
Publication TypeJournal Article
Year of Publication2015
AuthorsZhang, J-L, Tasan, CC, Lai, ML, Zhang, J, Raabe, D
JournalJournal of Materials Science
Volume50
Issue17
Pagination5694 - 5708
Date Published2015/09//
Abstract

Cold-worked alloys exhibit high strength, but suffer from limited ductility. In contrast, Ti-based gum metal was reported to exhibit high strength combined with good ductility upon severe pre-straining. Motivated by this anomaly, we systematically studied the evolution of gum metal microstructure during severe cold working (swaging and rolling) and the resulting deformation and damage micro-mechanical mechanisms during follow-up tensile deformation. To this end, various experimental in situ and post-mortem methodologies are employed, including scanning electron microscopy imaging, high-resolution electron backscatter diffraction mapping and transmission electron microscopy. These observations reveal that intense grain refinement takes place through dislocation plasticity-dominated deformation banding upon cold working. The observed enhancement in crack blunting and failure resistance which prolongs the post-necking ductility of gum metal during follow-up tensile straining can be attributed to the deformation-induced development of local heterogeneities in texture and grain size.