Wear Behavior of Al-Steel Solid State Coating Produced by Friction Surfacing

Abstract

Normally steels are coated with zinc or aluminium to protect them against atmospheric corrosion. Aluminium is being use as anode for the protection of ships, especially of war ships,marine vessels which are exposed to sea water. Aluminium deposition on mild steel by fusion welding is not feasible as it chemically reacts to form iron aluminide, and Fe and Al are immiscible. Hence, a solid state deposition is a possible option.

During Friction surfacing process rubbing of the rotating consumable rod against subtract, is pressed against the substrate under an applied axial load. Friction between rod and substrate generates a viscoplastic boundary layer at the rod tip. Temperature and pressure conditions lead to an inter diffusion at the interface resulting metallic bond between the plasticized material and the substrate.

In the present investigation, aluminum alloy coating on steel substrate developed by friction surfacing. AA6351 T6 used as a consumable material and SA516 Gr70 steel used as a substrate material. Al rod of the 22mm in diameter was selected for the deposition on 6mm thick steel plate using experimentally optimized variables. At constant FS variables multi-layer samples generated (single layer, double layer and triple layer). Afterwards samples subjected to metallurgical investigation includes microstructure, micro hardness and Pin on disc wear test at 60N load. Wear rate of multilayer specimens compared with original rod as well as with deformed rod. Wear rate of multilayer specimens is lower than that of original rod. Micro handedness value is higher at the interfaces, additionally mechanical interlocking observed at the interface.