Physica B 325 (2003) 130–137 Measurement of strain in a titanium linear friction weld by neutron diffraction Mark R. Daymond a, *, Neil W. Bonner b a ISIS Facility, CLRC Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX, UK b Rolls Royce Engines Plc., Derby, UK Received 8 July 2002; received in revised form 18 August 2002 Abstract We report measurements of strain by pulsed neutron diffraction in a titanium linear friction weld as a function of distance from the weld zone. While the average strains in a particular direction follow continuum mechanics expectations,examinationofstrainsindifferentcrystallographicdirectionshighlightstheprocessofgrainreorientation undergone during the welding. r 2002 Elsevier Science B.V. All rights reserved. PACS: 61.12; 07.10.P; 81.20.V Keywords: Neutron diffraction; Residual stress 1. Introduction Titanium alloys are widely used for structural applications, especially where high specific stiff- ness is required at elevated temperature. The bonding together of components made from dissimilar alloys is of particular interest for some of the modern, high-temperature titanium alloys used in the manufacture of today’s jet engines. Industryhasshownworld-wideacceptanceofboth the cost effectiveness and high weld quality which can be produced when using conventional rotary friction welding in order to produce joints in circular cross section metallic components. This interest has led to the development of linear friction welding (LFW), by which complex geo- metrycomponentscanbejoined,suchasjetengine blades to discs. LFW is particularly appropriate for titanium, due to the element’s great affinity for oxygen, nitrogenandhydrogen,whichrulesoutallwelding processesinwhichthemoltenmetalcancomeinto contact with any of these elements and result in embrittlement. The primary fusion welding meth- ods used are those carried out in an inert gas atmosphere (TIG and MIG welding). Friction welding,however,avoidstheformationofaliquid phase during the welding process, and can there- forebecarriedoutinair.Thesurfacesarejoinedin a plastic condition at hot forming temperatures. The typical defects caused by melting and solidi- fication such as pores, pinholes, shrinkage cracks, *Corresponding author. Tel.: +44-1235-445434; fax: +44- 1235-445720. E-mail address: mark.daymond@rl.ac.uk(M.R.Daymond). 0921-4526/02/$-see front matter r 2002 Elsevier Science B.V. All rights reserved. PII:S0921-4526(02)01514-4