Analysis on Cracking Failure of Support Plate of Drum Filter Net of a Rotary Vacuum Filter

Fragmentary cracking occurred on a rotary vacuum filter support plate after 5 a (annum) service. The plate was used about 2 a by replacing some parts, after that large area cracking failure appearing. The failure reasons were analyzed by means of macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscope analysis and energy spectrum analysis. The results show that the low content of Mo and Ni in the support plate, which makes the poor corrosion resistance of the filter support plate. The strain-induced martensite produced during cold processing further affects the corrosion resistance. The filters contains Br^-, which results in pitting on the filter support plate. Stress concentration was produced at the pitting position, which eventually leads to the stress corrosion cracking of the filter support plate.