TWI Industrial Member Report Summary 810/2004
Tasos Kostrivas, Lee Smith and Mike Gittos report on work carried out on sustained load cracking following a critical review undertaken previously at TWI.
Time-dependent failures in critical titanium alloy components such as aeroengine fan blades and certain offshore components have drawn attention to sustained load phenomena in these materials, be they 'cold creep', sustained load cracking, dwell fatigue or ripple fatigue. The basis for understanding static and dynamic sustained load phenomena was described in a critical review presented in a previous TWI report, which included data from literature and identified important mechanisms, environmental considerations and material factors. The present report presents the results of a programme of work aimed at generating threshold stress intensity factors (K ISLC ) for parent metal, and metal inert gas (MIG) and keyhole plasma arc welds in Ti-6Al-4V alloys, using two different rising stress intensity factor test methods.
- To generate threshold stress intensity factors for sustained load cracking (K ISLC values) in Ti-6Al-4V parent materials and weldments.
- To consider the influence of test method on derived K ISLC values.