Embrittlement failure of 51CrV4 leaf springs

Abstract

High strength quenched and tempered alloys are used in the manufacture of leaf springs, and peening techniques are used to induce compressive residual stresses on the tension surface of the individual leaves to resist fatigue crack growth. However, the extent of such residual stresses is usually limited to around 0.1–0.2 mm deep. Their beneficial effect can therefore be negated by corrosion pitting, while high strength steels are known to also be susceptible to environmental embrittlement in high chloride environments. This case study deals with an interesting example of environmental embrittlement of multileaf springs reportedly made from 60Si2Mn steel, but actually manufactured from 51CrV4 steel. Multiple cracks initiated from corrosion pits and fatigue failures occurred within 6–9 months from service entry of the vehicles. The embrittlement was triggered by the disinfecting and cleaning regime that reflected the use of the trucks for conveying animal feed.