Hot Salt Stress Corrosion Cracking and Corrosion Fatigue of Titanium Alloys

摘要

This work investigates the effects of high pressures on the hot salt stress corrosion cracking (HSSCC) of titanium (IMI834) under static (580MPa) and cyclic (0.1-580MPa) loading conditions at 500deg C. Pressures of 1 and 16 bar have been studied with a salt loading of 0.032mgcm~(-2). The influence of dwell at maximum stress has also been studied with dwell times of 5, 20 and 120 seconds. It is shown that for static loading, increasing the pressure from 1 to 16 bar increased the specimen life by approximately 14 times. The presence of cyclic loading was found to have a further damaging effect on the HSSCC, reducing the specimen lifetime when compared to those tested under equivalent static load conditions. By increasing the pressure and/or the dwell time an increase in lifetime was achieved. It is thought that high pressures inhibit the mechanisms by which hydrogen is introduced to the crack tip and cyclic stresses inhibit the formation of hydrides at the crack tip; both of which extend alloy life.