Effects of rapid solidification on the microstructure and surface analyses of laser-deposited Al-Sn coatings on AISI 1015 steel
01 Jan 2018-The International Journal of Advanced Manufacturing Technology (Springer London)-Vol. 94, Iss: 1, pp 773-787
TL;DR: In this paper, the enhancement in the corrosion, hardness and wear properties of Al-Sn binary coatings on AISI 1015 steel by laser alloying technique using ytterbium laser system (YLS) was investigated.
Abstract: Corrosion and wear phenomenon has been responsible for the gradual deterioration of components in industrial plants. This deterioration of components results in loss of plant efficiency, total shutdown and aggressive damage in a number of industries. Hence, surface modification and coating technique with enhanced surface properties is desirable. The study was designed to investigate the enhancement in the corrosion, hardness and wear properties of Al-Sn binary coatings on AISI 1015 steel by laser alloying technique using ytterbium laser system (YLS). A laser power of 1000 W, scanning speeds of 0.6 and 0.8 m/min, and alloy compositions of Al-75Sn, Al-50Sn and Al-25Sn were used in this study. Decrease in Sn content from 75 to 25% at different laser processing conditions resulted in improved properties. The enhanced properties were obtained at 75Al-25Sn alloy at laser power of 1000 W and speeds of 0.6 and 0.8 m/min. At optimum composition and speed of 0.8 m/min, there was enhancement of 53.63% in microhardness. At scanning speed of 0.6 m/min, 75Al-25Sn alloy exhibited the highest polarization resistance, R
p, (1.06 × 108 Ω cm2); lowest corrosion current density, I
corr, (3.12 × 10−7 A/cm2); and lowest corrosion rate, C
r, (0.00363 mm/year) in 3.65 wt% NaCl solution. In addendum, significant reduction in wear volume loss of 75Al-25Sn alloy at 0.8 m/min was attributed to excellent wear resistance performance due to metastable intermetallic phases. This research has established the enhanced surface properties of laser alloyed Al-Sn binary coatings on AISI steel for engineering applications.
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TL;DR: In this article, a 3kW continuous wave ytterbium laser system (YLS) was used to fabricate the coatings, and to control the movement of the cladding process, a KUKA robot was attached to the system.
Abstract: The marine, aerospace, and power machinery industries show progression in the application of titanium alloy components due to their good properties. However, the alloy exhibits poor thermal stability, low hardness, and poor tribological properties; as a result, the use of Ti6Al4V in various industries is restricted. Consequently, a search for surface improvement of Ti6Al4V alloy arose with the intention of enhancing its endurance. The use of laser metal deposition method by integrating chemical barrier coatings is considered as advantageous; therefore, an investigation aimed at surface improvement of Ti6Al4V by incorporation of Ti-Co coatings developed. To fabricate the coatings, a 3-kW continuous wave ytterbium laser system (YLS) was used, and to control the movement of the cladding process, a KUKA robot was attached to the system. The microstructure, corrosion, and mechanical properties of the titanium alloy-cladded surfaces were studied at different laser process parameters. To analyze the microstructure of the cross section, optical and scanning electron microscopy were employed. A laser power of 750 W and scanning rate of 1.2 m/min were found to be the optimum process conditions for a 60Ti-40Co alloy. When comparing the mechanical properties of the alloy and bare substrate, the alloy exhibited a significant increase in terms of the hardness. It was found to have 719 HV as compared to 301 HV which is that of the substrate, this indicates to an increase of 58.14% in the hardness. Lower laser scanning rates result in a larger fraction of hard-intermetallic phases which in turn lead to coatings with enhanced hardness levels. Furthermore, the yield strength and tensile strength of the coatings increased to maxima of 2.30 and1.66 GPa, respectively in comparison to the substrate, due to the addition of Co. Additionally, the corrosion rates of all the coated specimens were reduced as a result of the oxide films formed on the laser-coated Ti6Al4V alloy samples.
50 citations
22 Jun 2018
31 citations
01 Feb 2018
TL;DR: In this article, the effect of hybrid coatings of Al-Cu-Fe on a grade five titanium alloy (Ti6Al4V) using laser metal deposition (LMD) process at different laser power and scanning speeds was analyzed using Optical microscopy, Scanning electron microscopy (SEM), indentation testing, X-Ray Diffraction (XRD), corrosion and wear testing.
Abstract: Laser Additive Manufacturing is relatively new in the manufacturing industry. This paper focuses on the effect of hybrid coatings of Al-Cu-Fe on a grade five titanium alloy (Ti6Al4V) using laser metal deposition (LMD) process at different laser power and scanning speeds. Icosahedral Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. Ti6Al4V/Al-Cu-Fe composite were analysed using Optical microscopy, Scanning electron microscopy (SEM) with energy dispersive microscopy (EDS), indentation testing, X-Ray Diffraction (XRD), corrosion and wear testing. deposit width and height, heat affected zone (HAZ) height), dilution rate, aspect ratio and powder efficiency of each sample remarkably increased with increasing laser power due to the laser-material interaction. It was observed that there are higher number of aluminium and titanium presented in the formation of the composite. The indentation testing reveals that for both scanning speed of 0.8m/min and 1m/min, the mean hardness value decreases with increasing laser power. It was found that due to dilution effect, a part of Ti entered into molten pool from the substrate. The results indicate that Ti, Al 3 Ti, Ti 3 Al, CuTi 2 can be produced through the in situ metallurgical reactions during the LMD process.
30 citations
01 Feb 2018
TL;DR: In this article, a simulation of the heat transfer and fluid dynamics of the melt pool is developed to predict the process parameters and reinforcement proportions on the clad geometry quality, and the results were compared to the experimental results for confirmation and validation.
Abstract: Titanium Alloy (Ti6Al4V) opened a wide range of useful applications in aerospace industries; these industries make use of different additive manufacturing (AM) techniques to obtain parts of different properties for different uses by this titanium alloy. Ttitanium alloy mainly stands out due to the properties such as high specific strength to weight ratio, and excellent corrosion resistance. Despite these benefits, the formation of defects such as pores and cracks play a vital role in the quality of the deposited coatings. The presence of these unwanted artefacts on laser deposited coatings depends on the melting, cooling and solidification of the melt pool. In this research, a simulation of the heat transfers and fluid dynamics of the melt pool is developed to predict the process parameters and reinforcement proportions on the clad geometry quality. The results were compared to the experimental results for confirmation and validation. Numerical modelling using COMSOL multiphysics 5.2 revealed the thermal behaviour of the coated samples.
27 citations
TL;DR: In this article, a 3kW continuous wave ytterbium laser system attached to a KUKA robot was used to deposit coatings with stoichiometry Al-12Si-3Ti and Al-17Si-5Ti.
22 citations
References
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TL;DR: In this article, the authors compared the deduced dependence of the experimental observables on the load with the experimental evidence and concluded that the most realistic model is one in which increasing the load increases both the number and size of the contact areas.
Abstract: The interpretation of certain phenomena occuring at nominally flat surfaces in stationary or sliding contact is dependent on the assumed distribution of the real area of contact between the surfaces. Since there is little direct evidence on which to base an estimate of this distribution, the approach used is to set up a simple model and compare the deduced theory (e.g., the deduced dependence of the experimental observables on the load) with the experimental evidence. The main conclusions are as follows. (a) The electrical contact resistance depends on the model used to represent the surfaces; the most realistic model is one in which increasing the load increases both the number and size of the contact areas. (b) In general, mechanical wear should also depend on the model. However, in wear experiments showing the simplest behavior, the wear rate is proportional to the load, and these results can be explained by assuming removal of lumps at contact areas formed by plastic deformation; moreover, this particular deduction is independent of the assumed model. This suggests that a basic assumption of previous theories, that increasing the load increases the number of contacts without affecting their average size, is redundant.
5,771 citations
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TL;DR: The food-quality iron oxides are primarily distinguished from technical grades by their comparatively low levels of contamination by other metals; this is achieved by the selection and control of the source of the iron or by the extent of chemical purification during the manufacturing process as discussed by the authors.
Abstract: DEFINITION Iron oxides are produced from ferrous sulfate by heat soaking, removal of water, decomposition, washing, filtration, drying and grinding. They are produced in either anhydrous or hydrated forms. Their range of hues includes yellows, reds, browns and blacks. The food-quality iron oxides are primarily distinguished from technical grades by their comparatively low levels of contamination by other metals; this is achieved by the selection and control of the source of the iron or by the extent of chemical purification during the manufacturing process.
3,866 citations
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28 Sep 2004TL;DR: Mechanical Alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill as mentioned in this paper.
Abstract: Mechanical alloying (MA) is a solid-state powder processng technique involving repeated welding, fracturing, and rewelding of powder particles in a high-energy ball mill. Originally developed to produce oxide-dispersion strengthened (ODS) nickel- and iron-base superalloys for applications in the aerospace industry, MA has now been shown to be capable of synthesizing a variety of equilibrium and non-equilibrium alloy phases starting from blended elemental or prealloyed powders. The non-equilibrium phases synthesized include supersaturated solid solutions, metastable crystalline and quasicrystalline phases, nanostructures, and amorphous alloys. Recent advances in these areas and also on disordering of ordered intermetallics and mechanochemical synthesis of materials have been critically reviewed after discussing the process and process variables involved in MA. The often vexing problem of powder contamination has been analyzed and methods have been suggested to avoid/minimize it. The present understanding of the modeling of the MA process has also been discussed. The present and potential applications of MA are described. Wherever possible, comparisons have been made on the product phases obtained by MA with those of rapid solidification processing, another non-equilibrium processing technique.
3,773 citations
TL;DR: In this paper, a review is presented of the point defect model for the growth and breakdown of passive films on metal and alloy surfaces in contact with aqueous solutions, and the model provides a reasonable account of the steady-state properties of cation-conducting and anionconducting barrier layers on nickel and tungsten, respectively, in phosphate buffer solutions.
Abstract: In this paper a review is presented of the point defect model (PDM) for the growth and breakdown of passive films on metal and alloy surfaces in contact with aqueous solutions. The model provides a reasonable account of the steady-state properties of cation-conducting and anion-conducting barrier layers on nickel and tungsten, respectively, in phosphate buffer solutions; of the impedance characteristics of passive films on nickel; of the breakdown of passive films on a wide range of metals and alloys; of the distributions in the breakdown parameters (breakdown voltage and induction time); of the role of alloying elements in enhancing the resistance of alloys to passivity breakdown; of transpassive dissolution and electro-polishing; of erosion-corrosion; and of photoinhibition of pit nucleation. Additionally, the PDM has allowed us to formulate a set of principles for designing new alloys and has led to the development of a deterministic method for predicting localized corrosion damage functions.
1,148 citations
15 Mar 1998-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, a simplified methodology for investigating the effects of cooling rate from elevated temperature on phase transformations observed in α+β titanium alloys is described, which involves adaptation and refinement of a circumferentially insulated and instrumented Jominy end quench bar, time-temperature profiles obtained during cooling at locations along the bar length providing a complete thermal history.
Abstract: A simplified methodology for investigating the effects of cooling rate from elevated temperature on phase transformations observed in α+β titanium alloys is described. It involves adaptation and refinement of a circumferentially insulated and instrumented Jominy end quench bar, time–temperature profiles obtained during cooling at locations along the bar length providing a complete thermal history. The ability of this procedure to examine the phase transformation for α+β titanium alloys has been demonstrated in Ti–6Al–4V where varying cooling rates from 525 to 1.5°C s−1 are shown to result in a series of martensitic, massive and diffusional phase transformations. Cooling rates above 410°C s−1 result in a fully martensitic microstructure, a massive transformation being observed between 410 and 20°C s−1, this transformation being gradually replaced by diffusion controlled Widmanstatten α formation with decreasing cooling rate.
860 citations