Outside diameter corrosion – Unacceptable

Outside diameter corrosion – Unacceptable - Bearing defects

Figure 1: Outside diameter corrosion – unacceptable.

Defect name: Corrosion
Record No.: 1286
Type of defect (Internal/Surface): Surface
Defect classification: Bearing defects
Steel name: Steel
Steel composition in weight %: No data.
Note: Outside diameter corrosion – category L. Bearing outer rings having corrosion on the external surface greater than the following criteria shall be rejected from further service:
a) Contact area - individual pits up to 1 mm deep, no greater than 6 mm diameter or square, over a maximum of 25% of the contact area.
b) Non contact area (between support lands) – individual pits up to 2 mm deep and no greater than 10 mm diameter or square, over 25% of the non contact area.
Unacceptable outside diameter corrosion is shown in Figure 1. Severe corrosion is shown with multiple pits and a large area of pitting which exceeded 1 mm in depth.
Corrosion of the bearing outer surface is generally caused by water accumulating inside of the axlebox and keeping the bearing external surface wet. Moisture remaining between the axlebox raised lands and bearing outer ring set up an electrolytic cell which drives localised surface corrosion. This severe corrosion can result in pitting of the outer surface, which if sufficiently deep causes a stress raiser and consequential fracture of the ring.
Reference: Not shown in this demonstration version.