Scanning electron beam alloying of composite gradient coatings.

• Better preparation of alloy coatings by scanning electron beam technology. • The coating prepared by scanning electron beam showed a composite gradient. • The elements in the melt pool are sufficiently stirred to create segregation. • Martensite structure in the superheated zone can also be delaminated. The surface WC/Ni-Co based alloying treatment of 30CrMnSi steel was carried out using scanning electron beam technology, and the tissue distribution after alloying were tested and investigated. The results show that the cross-section of the alloyed specimen consists of three parts: the alloy layer, the heat affected zone and the substrate. The thickness of the alloy layer was increased by 18.3 μm compared to the thickness of the pre-coated layer. The alloy layer is organised in a composite gradient, consisting of martensite and ledeburite with carbides. [ABSTRACT FROM AUTHOR]