Hydrogen Embrittlement Failure in Suspension Leaf Springs 2007-01-4257

Multileaf steel suspension springs are occasionally prone to failure through delayed hydrogen stress cracking, a brittle fracture that can occur even before the springs have been assembled into a vehicle. This failure mode is unusual, and problematic in respect of diagnosis and prevention. Jai Parabolic Springs Ltd (JPSL), the world's fourth largest leaf spring manufacturer, experienced early failures of this kind in springs produced for a truck vehicle program in 2005. The root cause was shown to be delayed hydrogen stress cracking, or hydrogen embrittlement. Tests were conducted to assess the conditions leading to this type of failure. Guidelines are presented that were developed, and proved in production, to prevent future recurrence.