Influence of manganese on pack boriding behaviour of pure iron

Abstract

The boronising behaviour of pure iron and Fe–Mn alloys (1, 2, 4, 8, 12 and 16 wt-%Mn) was investigated by ‘pack boronising’ at 1100°C for 3 h to determine the effect of Mn. FeB and Fe₂B polyphase exist on all the boronised Fe–Mn alloys, and Fe–16 wt-%Mn alloy also has MnB₂ phase in the boride layer. The usual crack on the interface of FeB and Fe₂B was not observed for the boronised Fe–Mn alloys with 12 wt-% or more Mn. The same sawtooth-like morphology of the boride layer occurs on the pure iron and the Fe–Mn synthetic alloys without a clear transition zone. The distribution of Mn in the matrix and the boride layer is almost even. The average boride layer thickness is 280 μm and is independent of Mn content. The microhardness values are between 1700 and 2150 HV without a clear dependence on the amount of Mn.