Features of the Formation of the Structure and Properties of Magnesium Alloys during Additive Plasma Surfacing with Large-Diameter Wire

The development of new technologies for manufacturing products from magnesium alloys, with the aim to achieve high performance characteristics at reduced production costs, is a relevant problem. The study presents the results of research on additive manufacturing from high-strength magnesium alloy MA5 of the Mg–Al–Zn–Mn system by layer-by-layer plasma surfacing with a reverse polarity current using large-diameter filler wire. Plasma surfacing with a reverse polarity current with metered feeding of large-diameter filler wire provides good wetting and spreading of liquid metal with minimal heating of the surface. The resulting workpieces are characterized by minimum wall waviness and a favorable structure of the material, with no internal defects, regardless of the direction of filler wire feeding. It is established that plasma surfacing provides relative stability of structural and phase composition of the material along the height of the workpiece, while the degree of dispersion of the structure of the surfaced alloy MA5 is significantly higher than for cast and heat-treated structures of alloy ML5. Mechanical properties of the surfaced alloy MA5 are significantly higher than for the cast alloy ML5, both with and without heat treatment. The studies demonstrate that layer-by-layer plasma surfacing with metered feeding of filler wire enables the use of wrought magnesium alloys for the manufacture of products of specified shapes.