Crankshaft failure and why it may happen again

Abstract

This case study involves two continuously cast steel crankshaft failures. Three parties performed their own failure analyses: (1) the engine manufacturer responsible for component design, specification, and application; (2) the steel supplier and forging supplier responsible for making the steel, forging the shape, and preliminary heat treatment; and (3) a supplier that provided induction hardening, finish machining, and inspection. An independent fourth party engineering firm was subsequently involved, but because each party had their own agenda, there was no agreement on the metallurgical failure cause and therefore no continued analysis to pin-down and eliminate the root cause. A classic case showing how we may be doomed to repeat our failures because sound engineering was not allowed to proceed.