Microstructure and Mechanical Properties of Linear Friction Welded Titanium Subjected to ECAP

Abstract

Commercially pure (Grade 4) titanium specimens with two types of microstructure (coarse-grained and nanostructured by means of equal channel angular pressing) were joined by linear friction welding (LFW). Microhardness measurements, tensile and compression tests as well as fracture surface inspection by scanning electron microscopy revealed similarity in tensile properties and significant discrepancy in compression behavior of two types of Ti specimens. Tensile test shows that fracture occurs in both cases in a region of heat affected zone. Fracture surface analysis displayed mostly ductile mode. In case of compression test coarse-grained titanium linear friction welded demonstrates a pronounced strain hardening region without fracture but nanostructured LFW titanium shows typical plastic behavior with mixing of brittle-ductile mode of rupture in the welding zone.