Structure and Properties of Plasma Cladding of High-Speed Steel S2-9-2 (W2Mo9Al)

Abstract

The structure of four-layer coatings with a total thickness of 9 mm made of high-speed molybdenum steel S2-9-2 (W₂Mo₉Al) was studied. The coatings were obtained on a substrate of 41CrMo4 (30CrMnSi) steel by plasma cladding using a powder wire in a mixture of argon and nitrogen. The structure of the coating was studied by electron microscopy and energy-dispersive x-ray spectroscopy (EDS) on sample sections. It is shown that the microhardness of the deposited layer varies in the range of 5.2 – 6.6 GPa. This is due to the formation of an inhomogeneous structure in the deposited layer consisting of grains of an iron-based solid solution, at the joints and along the boundaries of which are inclusions of eutectic enriched mainly with Mo, Cr, and W. Grain sizes vary between 5 and 20 μm. A sub-grain structure is observed in the grain volume, indicating substructural hardening of the deposited layer. The sizes of the sub-grains vary between 1.5 and 2.5 μm. The layer of the alloy S2-9-2 deposited on 41CrMo steel exhibits a framework-like structure. The main alloying elements of the clad layer are Fe, Mo, Cr, W, and Al.