Corrosion investigation of stainless steel water pump Components, Engineering Failure Analysis, 2017, Vol. 82, pp. 466–473
Abstract
Two components of a water pump installed in a casting shop for recirculation of cooling
water experienced severe and accelerated corrosion after two months in service. The
received pieces of the water pump assembly were a shaft and a conical tube, which was
used as connector with the impeller. The shaft exhibited circumferential pitting corrosion
behavior in specific areas where it was in contact with another pump component. Light
optical microscopy and Scanning Electron Microscopy coupled with Energy Dispersive X-ray
Spectroscopy were mainly used as analytical techniques for corrosion process evaluation
and for the identification of the morphology and chemical composition of corrosion
products, in order to draw safe conclusions concerning the type of the corrosion and the
respective root-source. The main findings of the investigation indicated that pitting
corrosion was the dominant failure mechanism for both water pump components influenced
by the presence of aggressive environmental conditions, characterized by the presence of
chlorides and sulfates that accelerate corrosion process above a certain temperature range
(T > 50–55 °C).