A forged alloy steel arm of a lifting fork with an approximate cross section of 150 x 240 mm (5.92 x 9.45 in.) fractured after only a short service life on a lift truck. The fracture surface had the appearance of a fracture originating from a surface crack. Analysis (visual inspection, 200x micrographs, chemical analysis, and metallographic examination) supported the conclusion that the primary cause of the failure was the brittleness (lack of impact toughness) of the steel. The coarse bainitic microstructure was inadequate for the service application. The microstructure resulted from either improper heat treatment or no heat treatment after the forging operation. The surface cracks in the lifting-fork arm acted as starter notches (stress raisers), assisting in the initiation of fracture. No recommendations were made.

A few Cr-Mo steel piston rods from different production batches were found identically cracked in the eye end near the radius after chrome plating and baking treatment. Two of them cracked in the plating stage itself instantly broke on slight tapping. Cracking initiated from the outer base surface of the forked eye end. The 40 mm diam forged piston rods were subjected to plating after heavy machining on the part without any stress-relieving treatment. Also, time lapses between plating and baking were varied from 3 to 11 h. The brittle cracking along forked eye-end radius portion was attributed to hydrogen embrittlement that occurred during chrome plating.

This article is dedicated to the fields of mechanical engineering and machine design. It also intends to give a nonexhaustive view of the preventive side of the failure analysis of rolling-element bearings (REBs) and of some of the developments in terms of materials and surface engineering. The article presents the nomenclature, numbering systems, and worldwide market of REBs as well as provides description of REBs as high-tech machine components. It discusses heat treatments, performance, and properties of bearing materials. The processes involved in the examination of failed bearings are also explained. Finally, the article discusses in detail the characteristics and prevention of the various types of failures of REBs: wear, fretting, corrosion, plastic flow, rolling-contact fatigue, and damage. The article includes an Appendix, which lists REB-related abbreviations, association websites, and ISO standards.