Influence of manganese diffusion coating on fatigue behaviour of steels

Abstract

Manganese diffusion coating of steels, involving techniques similar to those used in chromium diffusion coating, has been reported in the past. In one study the powder packing process was used, and the three layers of coatings obtained were identified (from the outside inwards) as Mn₄N, γ-FeMn, and a mixture of α- and γ-phases of martensitic appearance, with Knoop hardness 900, 250–400, and 600–750, respectively. The coated variant also showed improved resistance to wear and to saltwater corrosion. Another study showed that, unlike its favourable effect in the case of pure iron, chromium diffusion coating has an adverse effect on the fatigue behaviour of steels. This is attributed to cracking of the brittle coating prior to application of the alternating load. The present study was aimed at understanding the fatigue behaviour of manganese-coated steels.