Aluminizing of the EP33 alloy by hot-dipping Kulevich, V P; Bogdanov, A I; Shmorgun, V G
Journal of physics. Conference series,
02/2024, Letnik:
2697, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract The features of hot-dip aluminizing of the EP33 alloy were studied and the structure transformation of the resulting coating during high-temperature treatment was investigated. Aluminizing ...the EP33 alloy leads to the formation of a continuous 120 μm thick coating, consisting of an aluminum matrix with the Cr 2 Al1 3 intermetallic compound inclusions and a continuous layer of FeAl 3 intermetallic compound along the boundary with the substrate. Heat treatment of the aluminized alloy at 1100 °C ensures the formation of a layered coating structure. The phase composition of the coating from the surface to the substrate changes in the following sequence: FeAl(Ni,Cr,Ti,Mo) → FeAl(Ni,Cr,Ti,Mo)+Ni(Fe,Cr,Al,Ti,Mo) → FeAl(Ni,Cr,Ti,Mo)+Fe(Al,Ni,Cr,Ti,Mo).
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.
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.
In this study, calculations and experiments were used to obtain the thermal conductivity equivalent coefficient value of layered (Ni
2
Al
3
+ CrAl
7
)/Cr20Ni80 coatings. The changes in the chemical ...composition because of the mutual diffusion of components, which determine the coating heat resistance, were analyzed. The simulation of the temperature field distribution over the cross section of the three-layer wall M1–Cr20Ni80–(Ni
2
Al
3
+ CrAl
7
) under conditions of reaching a stationary mode at an ambient temperature of 1600°C was performed using the DEFORM-2D software. The findings demonstrated that layered coatings (Ni
2
Al
3
+ CrAl
7
)/Cr20Ni80 could be considered heat-resistant and thermal barrier coatings. Such coatings provide high rates of high-temperature oxidation protection of copper air tuyeres of blast furnaces with minimal heat losses.
The regularities of formation of the diffusion coatings structure on the surface of the Fe–Cr–Al alloy during hot-dip aluminizing with ultrasonic impact are studied. The phase and chemical ...compositions of the coatings have been established. It is shown that the ultrasonic impact leads to a change in the intermetallic phase ratio of the coatings without affecting their composition. Exposure to ultrasound promotes the formation of continuous coatings while minimizing the contact duration between the substrate and high-temperature melt.
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.
This paper presents the study results of the diffusion interaction processes at the interlayer boundary of explosion welded Cr15Ni60-AD1 bimetal during the occurrence of homogeneous (at the solid - ...solid interface) and heterogeneous (at the solid - melt interface) reactions. It was shown that the diffusion zone formed during homogeneous interaction has a layered finely dispersed structure, while in a heterogeneous one it is predominantly needle-shaped with large fragments of the structure. Diffusion zones are characterized by heterogeneity in chemical composition, while their phase composition is almost identical: CrAl7, FeNiAl9, (Fe,Ni,Cr)Al9, (Fe,Ni,Cr)Al5, NiAl3, (Ni,Fe,Cr)Al. It has been established that the transition from the interaction at the solid - solid interface to the interaction at the solid - melt interface leads to a significant acceleration of diffusion processes.
The influence of heat treatment regimes on the structure and phase composition of the diffusion interaction zone at the interlayer boundary of the explosion-welded titanium VT1-0 + nickel NP2 ...composite is investigated. The mechanism of contact melting in the Ti–Ni system is proposed and experimentally confirmed. The temperature of the beginning of the process is experimentally determined. The influence of the temperature–time conditions of contact melting on the phase composition and structure of the obtained interaction zone is studied.
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.
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