Shirokobokova N. Surface strengthening of secondary silumins by laser treatment.

TThe object of research - processes of structure formation of surface layers of the alloy АК8М3 during laser treatment; the influence of the obtained structure on mechanical and service properties of the secondary silumin. The subject of research - the structure, mechanical and service properties of the secondary aluminium alloy АК8М3 with different iron content before and after pulse laser treatment. Purpose of the work - increasing of hardness, strength and service properties of hypoeutectic silumins by means of modification, heat and laser treatments. Research methods: spectral analysis of the alloys' chemical composition; optical microscopy, X-ray diffraction, X-ray spectrum and fractographic analysis; determination of microhardness, strength, percent elongation, fatigue fracture and wear resistance, cavitation and corrosion resistance. Obtained results - the optimal mode has been determined and regularities of the strengthened layer formation of the secondary silumin during the pulse laser treatment process have been established. Dependences of the increasing iron concentrations' influence on the mechanical and service properties of the alloy АК8М3 after modification, heat and laser treatments have been obtained. It has been established that laser treatment leads to the increase of the secondary silumin's microhardness by 1.6...1.7 times, ultimate strength - by 2 times, endurance limit - in average of 35 %, wear resistance under conditions of dry friction "metal to metal" - by 1.5...2 times, corrosion resistance in acid environment - by 2...3 levels. The work results have passed industrial approbation at JSC "Motor Sich", Ukrainian-Russian Enterprise "Soyuz", Ltd. The area of application is machine building.