Results are provided for a study of an aluminized coating corrosion resistance on the surface of alloys of the Fe–Cr–Al system (fechrals) and austenitic corrosion-resistant steel 12Kh18N10T under ...conditions of a temperate climate humid atmosphere containing chlorides. Coatings are applied by immersion in a melt. A study of corrosion during variable immersion of specimens in a 3% aqueous solution of sodium chloride show that coatings of the Fe–Cr–Al system prepared by aluminizing withstand long-term exposure to the environment (corrosion rate is 0.0003 g/(m
2
·day). An aluminized coating on a steel 12Kh18N10T surface has twice as good corrosion resistance indicators than for a coating on a Kh15Yu5 substrate.
This work studies the oxide film structure on the surface of cylindrical ingots made of 6000 series aluminum alloy after homogenization annealing and tests with alternating immersion in an ...electrolyte based on sodium chloride using electron microscopy and energy dispersive analysis. Results reveal a 40–200% increase in weight loss in areas covered with white bloom when the active environment impacts the ingot surface due to the presence of defects in the oxide film structure. In addition, the corrosion rate increases by a factor of 2–3 compared to the clean zones, while passivation processes are not noted on both parts of the surface. Defects in the structure of the oxide film are associated with the partial reduction of aluminum oxide during diffusion annealing at the site of contact with organic contaminants.
Electron microscopy and energy dispersion analysis are used to reveal structural features of an oxide film in the region of white deposit areas that are visually detected on the surface of ...cylindrical ingots of 6000 series aluminum alloy after homogenizing annealing. It is shown that a loose film of aluminum and magnesium oxides with an anomalously high Mg content (up to 45 at.%) and micropores are typical for these areas. Diffusion flow of magnesium towards the surface during homogenizing annealing gives rise to its chemical potential gradient occurring as a result of oxidation processes occurring during annealing. Reasons are determined for the occurrence of white deposit areas connected with formation at an ingot surface of mineral salt oxides and organic compounds from dried liquid used for cooling during ingot semi-continuous casting.
Abstract
Finite element simulation of tensile deformation of titanium-aluminum composite D20 – AD1 – VT6 was carried out. The joint boundary had a wave profile and local melts. 3D modeling of ...deformation of the composite D20 – AD1 – VT6 with a wave profile of the welded joint was carried out using the SIMULIA / Abaqus software. The relative thickness of the AD1 interlayer and the area of the melt were varied during the simulation. To determine for metal hardening during plastic deformation and the failure deformations for aluminum and aluminum alloy both Johnson-Cook deformation and fracture models was used. The influence of the size of the local melting zone and thickness of the soft interlayer on the distribution of stresses and strains in the composite is shown. The wave profile of the boundaries junction leads initially to localization of plastic deformation in the aluminum interlayer in the zone of free surfaces of the sample near the interface with the titanium alloy. A change in the length of vortices with areas of local melting near the tops of the wave profile from 0.3 to 0.8 mm had little effect on the profile of the curves “equivalent stress-absolute elongation of the sample”.
It is shown that in FeAl/Fe
3
Al/Fe(Al) coatings, formed on a steel substrate using explosion welding and subsequent heat treatment, the main failure mechanism is cohesive failure. Peeling and ...spalling of coatings occur only at high loads. It has been established that the hardness of a layered FeAl/Fe
3
Al/Fe(Al) coating with a thickness of 440 μm increases from the substrate to the surface, reaches a maximum at a distance of 200 μm from the surface, and then decreases due to an increase in porosity. Relative wear resistance of the coating is about 1.5 times higher than that of the steel St3 substrate.
In this study Al/Cu laminated composite specimens were obtained via explosion welding at various modes. Microstructure, chemical composition and microhardness of Al/Cu bond area were investigated by ...means of optical and SEM microscopy. Four typical microstructures of Al/Cu bond area were identified at different explosion welding parameters. The types included various amounts of molten zones in the structure. The evolution of the molten zone hardness value identified explosion welding regimes which contributed to maximum amount of intermetallic compound formation during explosion welding.
A 3D finite element simulation of the behavior of a prismatic sample of a magnesium-aluminum composite material AMg6-AD1-MA2-1 with an elliptical defect in the AD1 layer under axial tension was ...carried out, its strength and the change in the stress-strain state were determined when the thickness of the AD1 layer varied from 5 to 1, 25 mm. A change in the stress-strain state and strength during perforation transfer to the MA2-1 layer was revealed.
Diffusion zone growth kinetics and its phase composition after heat treatment of the bimetal obtained by explosive welding of copper M1 + magnesium alloy MA2-1 are studied. Thermal conductivity of a ...bimetal after welding and diffusion annealing are evaluated. The change in the textural state of magnesium alloy due to structural distortions during the formation of new phases is demonstrated.
It is shown that for the formation of Fe2Al5 intermetallic coatings on the steel surface the aluminized layer obtained by explosion welding must be subjected to a double heat treatment (660 °C, 3 h + ...640 °C, 3 h). The first heat treatment ensures the necessary size of the diffusion zone, and the second leads to the formation of a main crack at the interface of Fe2Al5 and FeAl3 intermetallides, which allows to separate the unreacted layer of aluminum and form a coating with hardness of 10 GPa. To form Fe2Al5 intermetallic coating on the steel surface, the aluminized layer, which is immersed in the melt, must be heat treated at 800 °C. The alloying of the diffusion zone by Si and Cu with the replacement of aluminum by the AK12M2 alloy leads to a decrease in the thickness of the diffusion zone and the appearance of additional phases of Al7Fe2Si and (Al,Si)5Fe3 in its composition. The duration of the subsequent heat treatment at 800 °C for complete dissolution of the surface layer increases the hardness of the resulting coating on the basis of a solid solution of Si in Fe2Al5 is 7.5-8 GPa.
The features of solid and liquid phase interaction at the interface of the explosion-welded composite fechral Cr15Al5 - aluminum AD1 are investigated. A way of increasing the aluminum content in the ...surface layer of the fechral Cr15Al5 after double thermal treatment is proposed.
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