FAILURE ANALYSIS ON BABBITT ALLOY BUSH FOR NUCLEAR POWER PLANT

The thorough analysis was made on adhesive failure and cracking in the surface of Babbitt bush. Segregation, mass and delaminating phenomenon were found in microstructure of Babbitt alloy layer, and also found a lots of porosity near the interface between body and Babbitt alloy layer, formed from unsuitable foundry processing. The cast defects were apt to form stress concentration and finally resulted in cracks initiation and propagation. The chemical analysis showed that the hydrogen content near interface were higher than that in others, the swell would occur in the surface of Babbitt alloy with hydrogen diffusing and massing when the bush run with high temperature and stress, which would distort the lubricant condition and form adhesive failure and cracks.