| In this paper, the organization, composition, surface morphology of tensile fractureand alloy corrosion of spray forming7055aluminum alloy were analyzed by the frictionand wear test, the room temperature mechanical properties testing, slow strain rate tests andAC impedance spectroscopy analysis, using optical microscopy, friction and wear apparatus,scanning electron microscopy, spectroscopy and electrochemical impedance spectroscopy.There are researched that friction and wear properties of spray forming7055aluminumalloy、the influence of the aging system to stress corrosion resistance and electrochemicalcorrosion resistance of spray forming7055aluminum alloy.The organization of spray forming is compact without macro-segregation and grainsize is small and uniform distribution compared with casting; Experimental material istreated by Aging process: single-stage aging （120℃/24h） or duplex aging （120°C/8h+160℃/6h;120℃/8h+160℃/10h;120℃/8h+160°C/15h）, The Brinell hardness ofsingle-stage aging is up to202HB, compressive strength is749.2524MPa, The Brinellhardness of single-stage aging is gradually reduced from185HB to160HB; the frictioncoefficient of the alloy is turbulent-like fluctuations during the whole experiment, and as thetemperature increasing, the turbulent fluctuations are more intense. the average frictioncoefficient μk increased gradually with the temperature increasing, μk is0.423872at roomtemperature, μk respective is0.437228and0.602063at100°C and200°C, whentemperature is up to300°C, the average friction coefficient μk is close to the ultimate value1.00; adhesive wear form of7055aluminum alloy changed from general adhesive wear toabrasion wear and tear and glue wear with the temperature increasing.Under different strain rates、the same aging process and the corrosive environment,Only at the strain rate of0.5x10-6S-1between1.0x10-6S-10.8x10-6S-1,0.5x10-6S-10.2x10-6S-1four stretching rate, the intensity of the aluminum alloy compared the tensile strength inthe air is more obviously reduced, the plasticity loss is obviously improved, was up to about-30%, the stress corrosion susceptibility of alloy is great,stress corrosion resistance of alloyis poor; Alloy tensile strength was greatly reduced when the two aging time is extended to15h, the intensity is about580MPa, elongation is significantly improved, is up to5mm. Even if the strain rate of0.5x10-6S-1, the alloy did not show significant plasticity loss,becoming insensitive to stress corrosion, stress corrosion resistance of alloy was significantly improved; At the strain rate of0.5x10-6S-1,morphology analysis on tensilefracture except whose aging process is120℃/8h+160℃/15h scanned by SEM showed thatthe air tensile fracture surfaces is ductile fracture, while the tensile fracture surfaces incorrosive medium was quasi-cleavage of brittle fracture, therefore, the alloy stress corrosioncracking mechanism is quasi-cleavage fracture; Theory of anodic dissolution and hydrogeninduced fracture mechanism was synergistic effect to stress corrosion cracking of sprayforming7055aluminum alloy. Crack propagation of spray forming7055aluminum alloy wasdecided to Hydrogen embrittlement, the anodic dissolution created the critical defects, andpromoted the hydrogen discharge, migration and hydrogen embrittlement.Contrasting the time entering the pitting stage between single-stage aging process andduplex aging, the corrosion microscopic morphology of alloy surface, ac impedancespectrascopy and the rate of decline of impedance modulus in Bode plot, the resistance toelectrochemical corrosion of duplex aging is better than single-stage aging; inducedcorrosion of pitting to different aging processes is different: single-stage aging isinter-granular corrosion, while the two-stage aging is local pitting; Electrochemicalprocess of corrosion control is controlled by activation at the initial,then the diffusionprocess of corrosion product film on the electrode surface is controlling step after720h. |
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