Addition Of Metal Powder Research Articles

A new concept of inoculation by isomorphic refractory powders and its mechanism for grain refinement

Isomorphic Inoculation (ISI) is a novel grain refinement technique during solidification by the addition of metallic powders to the melt rather than ceramics. The powders are designed to grow epitaxially rather than to nucleate new solid, increasing theoretically the ratio between solidified grains and inoculants to 1:1. This technique circumvents the energy barrier problems related to heterogenous nucleation in traditional grain refinement techniques. In this manuscript, we show through a combination of numerical and experimental techniques that this ratio could be reached. This is achieved through novel experimental techniques to replicate the effects of the melt on the powders. A new CaF molten salt experiment was used to, for the first time, show the recrystallization/grain growth of Ti powders at high temperature. In parallel, we calibrated a model on our experimental conditions and used it to calculate the dissolution rate of the powders in the melt. The combined effects of grain growth, preferential grain boundary dissolution (increasing the number of powders) and bulk dissolution (decreasing the number of powders) act together, bringing the number of particles present during solidification near that of the number of solidified grains found in the sample ingots. The per particle efficiency of this method is far in excess of traditional inoculation methods and has the potential for wide applications, especially in systems such as TiAl used here where the heterogeneous particles remaining in the as-cast material are undesirable.

DETERMINATION OF FLAVONOID CAPACITY BY USING ETHANOL EXTRACT OF CIPLUKAN LEAVES (Physalis angulata L.) USING UV-VIS SPECTROFOTOMETRY METHODS

Ciplukan leaves (Physalis angulata L.) have a composition of main phytochemical compounds including alkoloids, phenolics, tannins, flavonoids that can function as antioxidants, antibacterial, antiviral, anti-inflammatory, antiallergic, and anticancer. The purpose of this study was to identify and determine the levels of flavonoid compounds contained in the Ethanol Extract of Ciplukan Leaf (Physalis angulata L.) Ethanol extraction of Ciplukan Leaves (Physalis angulata L.) was carried out using the maceration method using 96% ethanol solvent, a flavonoid identification test was carried out on the Ethanol Extract of Ciplukan Leaves with the addition of Mg metal powder, concentrated HCI, and 10% NaOH, then determining Flavonoid levels using the UV-Vis spectrophotometric method using Quercetin as a comparative raw material. A qualitative test of Ethanol Extraction of Ciplukan Leaves (Physalis angulata L.) containing flavonoids has been carried out. Determination of flavonoid levels using UV-vis spectrophotometry obtained 0.0235%.

Limits on Ti Element Transfer in Submerged Arc Welding: Thermochemical Analysis

TiO2 inclusion formation in the weld pool is required to produce potent nucleation sites for acicular ferrite microstructure formation. Weld metal oxygen content must be limited to ensure acceptable materials properties, although sufficient oxygen is required for inclusion formation. Weld pool oxygen is sourced from the decomposition of flux oxides. Weld metal oxygen is controlled with flux chemistry formulation by CaF2 dilution of oxides. In conventional submerged arc welding (SAW), the flux is the source of weld metal Ti. Transfer of Ti from the slag appears to be limited to 400 parts per million (ppm). SAW modification by metal powder additions changes the element transfer reactions. Thermochemical analysis is applied to explain the limitations in Ti transfer from the slag, compared to improved reaction conditions for Ti element transfer in the aluminum‐assisted Ti alloying of weld metal. Low TiO2 activity due to low flux TiO2 content from CaF2 dilution and Ti loss from Ti‐fluoride gas formation limits Ti transfer from slag. Aluminum‐assisted alloying of the weld metal shifts the gas composition from Ti‐fluoride formation to Al‐fluoride formation and lowers the system partial oxygen pressure to increase the weld metal Ti content, with acceptable ppm O remaining in the weld metal.

EERZ (Effective Equilibrium Reaction Zone) Model of Gas-Slag-Metal Reactions in the Application of Unconstrained Al-Ni-Cr-Co-Cu Metal Powders in Submerged Arc Welding: Model and 3D Slag SEM Evidence

The scope of this work is to improve the SAW process understanding and present an improved description of the SAW process in terms of gas-slag-metal reactions with alloy powder and Al powder additions. The scope does not include the materials properties of the weld metal. The latter may easily be optimised in the future by changing the weld metal chemistry once the process reactions of different element powders in SAW are understood. Aluminium as de-oxidiser element was applied to SAW to lower the oxygen partial pressure in the process. The results show the Al-Ni-Cr-Co-Cu alloyed weld metal total oxygen content was reduced to 257 ppm O, compared to the base case weld metal at 499 ppm O, made with the same flux and no metal powder additions. Thus, the aluminium that was added as a de-oxidiser element to the SAW process effectively lowered the original flux-induced partial oxygen pressure, both in the arc cavity and at the interface of the molten flux–weld pool phases. This partial oxygen pressure lowering effect of Al also prevents oxidation of Cr, preventing loss of Cr to the slag. Carbon steel was alloyed to 3.9% Al, 4.8% Ni, 4.9% Cr, 4.8% Co, 4.7% Cu at 62% Al yield, 76% Ni yield, 77% Cr yield, 75% Co yield, 74% Cu yield. SEM (scanning electron microscope) work on the three-dimensional (3D) post-weld slag sample show dome cavities with 3D rounded structures embedded in the dome cavity walls, as well as shards and nano-strands on the dome cavity walls. The 3D structures indicate vapour formation and re-condensation of oxy-fluorides. The novel application of the EERZ (effective equilibrium reaction zone) model simulates the mass transfer effects in the SAW process. This model is novel because it is the first model used to calculate the gas-slag-metal phase chemistry changes in SAW as a function of welding time. The novel SAW process modification of adding Al de-oxidiser powder with alloying element powders of the unique combination of Co-Cr-Co-Ni-Al was successfully applied. The results confirm that the gas phase and its reactions must be included in the interpretation and modelling of SAW process metallurgy.

Gas Formation of Cobalt and Copper in the Application of Unconstrained Co-Cr-Al-Cu Metal Powders in Submerged Arc Welding: Gas Phase Thermodynamics and 3D Slag SEM Evidence

Aluminium metal is not typically added to the submerged arc welding (SAW) process because it is easily oxidised to form unwanted slag in the weld pool. The successful application of aluminium as a de-oxidiser is illustrated in this study by preventing oxidation of Cr and Co to their oxides, thereby preventing element loss to the slag. Unconstrained pure metals of Al, Cr, Co and Cu were applied to investigate the gas formation behaviour of these elements in the SAW arc cavity. Of interest is the effect of copper in the arc cavity in terms of its possible substitution for aluminium. The results confirmed that the Al-Cr-Co-Cu alloyed weld metal total oxygen content was lowered to 176 ppm O, in comparison to 499 ppm O in the weld metal formed from welding with the original flux, which excluded metal powder additions. This lower ppm O value of 176 ppm O confirms that the added aluminium powder effectively lowered the original flux-induced partial oxygen pressure in the arc cavity, and at the molten flux–weld pool interface. Carbon steel was alloyed to 5.3% Co, 5.5% Cr, 5.3% Cu and 4.5% Al at 78% Co yield, 82% Cr yield, 78% Cu yield and 66% Al yield. Thermochemical equilibrium calculations confirm the partial oxygen pressure-lowering effect of aluminium when considering the gas–slag–alloy equilibrium. BSE (backscattered electron) images of the three-dimensional (3D) post-weld slag sample show dome structures which contain features of vapour formation and re-condensation. SEM-EDX (scanning electron microscope-energy dispersive X-ray) maps show that the dome surface matrix phase consists of Al-Mg-Ca-Si-Na-K-Ti-Fe-Mn oxy-fluoride. The spherical 3D structures of 10–40 µm in diameter consist of Fe-Mn-Si fluorides with some Cr, Cu and Co contained in some of the spheres. Cr and Co were observed in distinctive porous structures of approximately 10 µm in size, consisting partly of Cr oxy-fluoride and partly of Co oxy-fluoride. Nano-sized oxy-fluoride strands and spheres in the dome structures confirm vaporisation and re-condensation of oxy-fluorides. Cu and Na formed a distinct condensation pattern on the surface of the Si-Cu-Na-Mn-Fe-Co oxy-fluoride sphere. The results confirm the importance of including gas phase reactions in the interpretation of SAW process metallurgy.

In Ukrainian

In this paper it is discussed the colloidal-chemical method of synthesis of dispersed composite bentonite-ferromagnetic powders that are stable to oxidation. It is shown that for this purpose it is advisable to use acid-activated bentonite clay with a high content of clay mineral - montmorillonite. Modified bentonite is a slightly amorphized silica product that serves as a porous matrix for crystallization of goethite α-FeOOH. The formation of goethite occurs at the centers of crystallization - particles of ferrihydrite stabilized by activated bentonite (Fh) during precipitation with an ammonia solution from a ferrum(ІІІ) hydroxide FeO(OH)×nH2O colloidal solution. In the resulting composite, goethite particles are cemented in the aluminosilicate framework of activated dispersed clay as a result of the interpenetration of the structures of the double layered hydroxide and activated bentonite. Further recrystallization of goethite with the formation of mainly magnetite and possibly maghemite in the structure of activated bentonite is provided by thermal firing of composite goethite powder with the addition of metallic iron powder. The methods of IR spectroscopy, X-ray structural analysis, electron microscopy and the study of magnetic properties showed that the obtained composite powder is environmentally friendly and exhibits the properties of a soft magnetic material. Such powders are promising for use as sorbents for environmental cleaning, as well as for biomedical purposes due to their low toxicity and high value of saturation magnetization.

Application of Composite Filament with the Addition of Metallic Powders in 3D Printing

The aim of this experimental research was to 3D-print a filament based on PLA plastic with a metallic powder. The filament contained approximately 80 – 90 % of copper powder. The base component of the filament is thermoplastic PLA, a polymer belonging to the group of aliphatic polyesters. Composites based on PLA and powders have different properties from traditional PLA filaments without admixtures. The created composite structure is intended for 3D printing with the FDM (Fused Deposition Modeling) technology, using rapid prototyping. The printed samples were subjected to the sintering process. The fractures of the sintered samples were SEM and EDS analyzed.

Modification of Flux Oxygen Behaviour via Co-Cr-Al Unconstrained Metal Powder Additions in Submerged Arc Welding: Gas Phase Thermodynamics and 3D Slag SEM Evidence

Aluminium metal is avoided as main reactant in submerged arc welding (SAW) because it is easily oxidised in this process. Aluminium is an effective de-oxidiser and can be used to prevent Cr and Co loss to the slag by preventing oxidation of these metals. In our novel application of aluminium metal powder in SAW we demonstrate the modification of flux oxygen behaviour. The Co-Cr-Al-alloyed weld metal total oxygen content is decreased to 180 ppm O, compared to 499 ppm O in the weld metal from the original flux, welded without metal powder additions. The flux oxygen behaviour is modified by the added aluminium powder through the lowering of the original flux-induced partial oxygen pressure in the arc cavity and at the molten flux-weld pool interface. Carbon steel was alloyed to 5.9% Co, 6.3 % Cr and 5.1% Al at 81% Co yield, 87% Cr yield and 70% Al yield. Gas-slag-alloy thermochemical equilibrium calculations confirm the partial oxygen-pressure-lowering effect of aluminium. BSE (backscattered electron) images of the three-dimensional (3D) post-weld slag sample show dome structures which contain features of vapour formation and re-condensation. These features consist of small spheres (sized less than 10 μm) and smaller needle-shaped particles coalescing into a porous sphere. EDX analyses show that the spheres consist of Si-Na-K-Fe-Mn-Co-Cr oxy-fluoride and the needles consist of low oxygen Si-Al-Ca-Mg-Na-K-Fe-Mn-Co-Cr oxy-fluoride. The element distribution and speciation data from the EDX analyses confirm modification of the flux oxygen behaviour via aluminium powder addition in lowering the partial oxygen pressure, which in turn prevents oxidation of Cr and Co and minimise losses to the slag.

3D particle sizing, thermometry and velocimetry of combusting aluminized propellants

Due to the unique advantages of high specific impulse, high thrust, simplicity and reliability, solid propellant with metal powder additives has emerged as a promising energy carrier for rockets in aerospace engineering. In-situ characterization of the metal particle combustion is crucial for the validation of numerical models and optimization of the propellant formulas. Previous studies mainly focused on the measurement of particle size and velocity near the combusting propellant surface with holography. Whereas, the behavior of the particles away from the surface is also essential for the full understanding the combustion and agglomeration mechanisms. Nevertheless, holography suffers from inaccurate depth estimation due to the large depth-of-focus. To overcome this limitation, a hybrid method which combines three-dimensional (3D) fiber optic imaging with two-color pyrometry is developed to realize simultaneous 3D localization, velocimetry, sizing, and thermometry of combusting aluminum particles in a large field of view. The method is validated both with numerical studies and experiments for a field of view of ∼60 × 50 × 50 mm3. According to the experimental results, the particle size follows a log-normal distribution which agrees with the specification of the propellants. In addition, the evolution of particle temperature and velocity were recorded for a duration of ∼13.9 ms. The results suggest that the temperature of most particles were between 2000 and 3500 K, while particle velocities were between 1 and 10 m/s. The measurement method proposed here is promising for the quantitative analysis of the complicated combustion process of aluminized propellants.

Iron Extraction from South African Ilmenite Concentrate Leaching by Hydrochloric Acid (HCl) in the Presence of Reductant (Metallic Fe) and Additive (MgSO4)

The high content of iron in ilmenite ore poses a great challenge, particularly in the synthesis of titanium-containing products due to high susceptibility of iron (Fe) to corrosion. Direct leaching of ilmenite ore in hydrochloric acid (HCl) encouraging Fe dissolution was investigated. The influence of variable parameters, the use of additives, and the addition of metallic iron powder were studied to establish the optimum leaching parameters. The results showed that ilmenite with the particle size distribution of +150 µm yielded better efficiencies when leaching was performed with an acid concentration of 7.5 M and a solid-to-acid ratio of 1:10 at 90 °C. An agitation speed of 450 rpm yielded a superior Fe extraction of about 92.32% and a 2.40% titanium (Ti) loss. The addition of both metallic Fe and the MgSO4 additive significantly enhanced Fe dissolution and decreased Ti recovery in a leach solution. It was found that leaching under optimum conditions produced a solid residue with 1.37% Fe impurity while 98.63% was extracted. The leached residue was comprised of 91.4% TiO2 rutile phase and contained a high content of the ilmenite FeTiO3 (4.37%) and SiO2 (2.23%) impurities, while Al2O3, MgO, MnO2, CaO, V2O5, MnO2, and Cr2O3 were below 0.13%. The high TiO2 content in the leached residue makes it suitable for use as feed in the production of synthetic rutile. The leaching kinetics of Fe dissolution was found to conform to the shrinking core model, where diffusion through the product layer is rate controlling. The calculated activation energy according to the Arrhenius equation was 19.13 kJ/mol.

3D Printing Techniques for Paraffin-Based Fuel Grains

Hybrid rocket propulsion systems have proved to be a suitable option for some specific applications in the space transportation domain such as in launch vehicle upper stages, orbit transfer spacecrafts, decelerator engines for re-entry capsules, and small satellites launchers. Part of the renewed interest in hybrid rocket propulsion is due mainly to the safety aspects, cost reduction, and the use of paraffin-based fuel that impacts positively in terms of the solid fuel regression rate. However, paraffin solid fuel grains have poor structural characteristics and sometimes low performance due to the fuel internal ballistics behaviour. More recently, various studies have been carried out to overcome these drawbacks of paraffin-based fuels, such as the addition of energetic nano-sized metallic powder and 3D printing techniques. This study presents a review of the principal concepts of 3D printing processes and extrusion techniques that can be suitable for paraffin grains manufacturing and the conceptual design of a prototype for a 3D printer system under development at the Aero-Thermo-Mechanics Department of Université Libre de Bruxelles.

In Situ Modification of CaF2-SiO2-Al2O3-MgO Flux Applied in the Aluminium-Assisted Transfer of Titanium in the Submerged Arc Welding of Carbon Steel: Process Mineralogy and Thermochemical Analysis

Flux formulations are specified to target chemical and physico-chemical parameters. Chemical parameters set flux element transfer behaviours and weld metal oxygen contents. Physico-chemical parameters such as slag viscosity, surface tension and melting range are targeted to ensure an acceptable weld bead profile and surface appearance. Slag detachability is an important physico-chemical property required to ensure high welding productivity, smooth weld bead surface and no slag entrapment. Here, bead-on-plate welding tests were made with and without metal powder additions, including aluminium powder as a de-oxidiser. Difficult slag detachability was observed in weld runs made with metal powder additions. Mineralogy of the post-weld slags, and thermochemical calculations, show that the flux was modified due to the aluminothermic reduction of MnO and SiO2 from the slag to form alumina. Increased quantities of spinel phase were identified in the post-weld slag samples, at the weld pool–slag interface. The combined effect of increased slag viscosity, from increased spinel in the slag, and lowered weld pool solidus temperature, resulted in the formation of a rough bead surface morphology, which, in turn, caused mechanical fixation of the slag to the weld bead. Flux modification to higher CaF2 content should ensure that higher quantities of spinel phase can be tolerated in the slag.

Anaerobic Reactor Filling for Phosphorus Removal by Metal Dissolution Method.

A commonly indicated drawback of anaerobic wastewater treatment is the low effectiveness of phosphorus removal. One possibility to eliminate this disadvantage is the implementation of active fillings that contain admixtures of metals, minerals, or other elements contributing to wastewater treatment intensification. The aim of the research was to present an active filling produced via microcellular extrusion technology, and to determine its properties and performance in anaerobic wastewater treatment. The influence of copper and iron admixtures on the properties of the obtained porous extrudate in terms of its functional properties was also examined. The Barus effect increased with the highest content of the blowing agent in the material from 110 ± 12 to 134 ± 14. The addition of metal powders caused an increase in the extrudate density. The modification of PVC resulted in the highest porosity, amounting to 47.0% ± 3.2%, and caused the tensile strength to decrease by about 50%. The determined values ranged from 211.8 ± 18.3 MPa to 97.1 ± 10.0 MPa. The use of the filling in anaerobic rectors promoted COD removal, intensified biogas production, and eliminated phosphorus with an efficiency of 64.4% to 90.7%, depending on the type of wastewater and applied technological parameters.

Aluminium-Assisted Alloying of Carbon Steel in Submerged Arc Welding: Application of Al-Cr-Ti-Cu Unconstrained Metal Powders

Al assisted alloying of carbon steel in Submerged Arc Welding (SAW) by Al-Cr-Ti-Cu unconstrained metal powders is applied. A base case without metal powder additions is compared to two metal powder addition schedules, Al-Cu-Ti and Al-Cu-Ti-Cr. Al powder is used as a deoxidiser element to control the oxygen partial pressure at the weld pool–molten flux interface to ensure that most of the Ti and Cr metal powder is transferred into the weld pool and that the weld metal ppm O is controlled within acceptable limits of 200 to 500 ppm O. The likely sequence of alloy melt formation is deduced from the relevant alloy phase diagrams. The effect of Fe addition into the initial Al-Cu-Ti and Al-Cu-Ti-Cr alloy melt is illustrated in thermochemical calculations. Increased metal deposition productivity with metal powder addition in SAW is confirmed. The metal deposition rates increased by 19% and 40% when Al-Cu-Ti and Al-Cu-Ti-Cr powders were applied at the same weld heat input used in the absence of metal powder additions.

Tribological Characteristics Near Welding Limit for Petroleum Metal Pipelines

Welding process is one of the most widely applied processes in the industry. This is due to the ease of the process and it's a quantitative process. The addition of metallic powders to the welding area has not been widely emphasized as a solution to amelioration the tribology characteristic of the welding area therefore the effect of adding metallic powders (SnS nanoparticles) to the welding area on tribology properties was studied. This effect was studied at the values of coefficient of friction, coefficient of wear and wear rate by using the ring – on – disc sliding wear test equipment was used to study the tribological behavior of low carbon steel (A 106 grade B) as pure, 6010 welded and SnS- 6010 welded) under changing loads with constant velocity and in one hour for each run the dry condition at ambient temperature. The results show the coefficient of friction, coefficient of wear and wear rate increased with up load.

Combined effects on Fe-Cr-C hardfacing deposited by new technique FCDW-GTAW

The hardfacing deposition with the GTAW process is widely studied with the addition of metallic powder or solid wire. This study introduces an original method, flux-cored-double-wire GTAW (FCDW-GTAW), where wires of different compositions are used simultaneously to deposit hardfacing. Because of the complexity in stabilizing the welding system, the combined effects of welding parameters should be investigated, allowing elaborate prediction models for the geometry and dilution of the deposits. These aspects are crucial for the target application, wear-resistant layers based on Fe-Cr-C composition, requiring a low-level of dilution and bead-geometry quality. Five parameters were chosen to model the deposition: the welding current, welding speed, standoff distance, torch angle, and wire feed pulse frequency. Therefore, using Response Surface Methodology with five factors at five levels to plan the experiments, thirty-two deposition conditions were necessary to model responses. Complete and reduced models were presented for width, reinforcement, penetration, and dilution responses. The reduced models showed a better prediction than the complete ones. The welding parameters’ interaction was identified for the reduced models, where the welding current and speed were influential in all responses. Results showed the possibility of obtaining good quality in the beads applying the FCDW-GTAW technique.

Development of oxide-free oxide materials under conditions of plasma-spark sintering of a mixture of oxide-free components and the addition of various metal powders

Effect of powder additives of W and Mo during spark plasma sintering of com-positions at pressing loading of 60 MPa in the range 1200‒1600 °С on the phase composition, microstructure, grain sizes of crystalline phases, relative density, linear shrinkage, physical-mechanical properties and linear correlation of modulus of Elasticity and fracture toughness of mullite‒ZrB 2 ‒β-SiC‒TaC samples was shown. Synthesised powders of ZrB 2 , β-SiC and TaC are characterisized by intensive crystal-lization of ZrB 2 , β-SiC and TaC cub , respectively. Sintered samples with additives of W and Mo powders show intensive mullitization, active crystallization of β-SiC, (Zr, Ta)B, C, β-WC and β-WB in comparison with lower crystallization of (Ta, Zr)C, B, β-MoC, β-MoB and MoB 2 in the range 1200‒1600 °С. Microstructure of sample with molybdenum additive at 1500 °С more uni-formly and densely sintered, crystalline, containing less quantity of pores and weakly sintered areas, more reinforced at the boundaries areas of oxide-nonoxide and nonoxide crystalline phases. Such sample is characterisized by smaller grains sizes of crystalline phases in the range 1400‒1600 °С and show uniform growing of relative density and linear shrinkage, physical-mechanical properties with larger their values, higher resistance to the cracking with propagation of micro-cracks by meandering path as well as larger linear correlation of modulus of Elasticity and fracture toughness in the range 1200‒1600 °С.

Microstructural characterization and mechanical properties development with Ti, Cr, or Ni addition for low carbon steel butt joints

Welding is one of the most important industrial process, therefore many practical techniques are developed to obtain an efficient and cost effective welding for different kind of metals. In this research, the microstructural characterization and mechanical properties of welded joints using TIG welding were studied for 1020 AISI low carbon steel. Titanium, Chromium, or Nickel powder were added to the welded joint one at a time by paste it with paraffin wax in the form of a thin layer. The welds were conducted and tested, then results were compared with and without adding Ti, Cr, or Ni metal powder. The welding process was done at a constant DC current (200 Amps. and 20 Volts) using weld filler metal type ER70S-3. Tests results showed that the tensile strength of the welded joint without adding metal powders was approximately 2% higher than the tensile strength of the base metal. Additionally, the tensile strength enhanced by approximately 27%, 21%, and 2% for Titanium, Nickel, and Chromium metal powder addition to the welded joints respectively. The bending strength values for all welded joints were also higher than the base metal. Furthermore, the hardness values were increased in the welded zone for all specimens. This can be attributed to the difference in the behavior of each metal powder at high temperature. The obtained results provide an experimental reference for the development of a new welding technique. It can be used in practical welding applications to obtain the desired properties using a suitable metal powder or a combination of them.

Studying the Effect of Adding Metal Powders on the Mechanical Properties of Spot Welds for Low-Carbon Steel Sheet

Spot welding process is one of the most widely applied processes in the industry. This is due to the ease of the process and it’s a quantitative process. The addition of metallic powders to the spot welding area has not been widely emphasized as a solution to amelioration the mechanical characteristic of the welding area therefore the effect of adding two types of metallic powders, (namely nickel powder and titanium powder), to the spot welding area on mechanical properties was studied. This effect was studied at the values of different welding currents and at different welding times to indicate the impact of these factors on the mechanical properties of the welding area.theresluts show that the increasing in welding time and welding current enhenced the mechanical properties of the weld nugget, in addition to that the addition of Ni and Ti metal powder improve the strength of the welds, and the Ti metal powder had a higher effect on the mechanical properties than the Ni powder metal.

Effectiveness of metal powder additions for martensitic hardfacing alloy on its wear properties

Selecting welding consumables to get satisfactory results in hard facing weld repair jobs at a low cost is an important consideration. The standard martensitic welding electrodes used for hardfacing are expensive, so an investigation into finding suitable substitutes is a worthwhile activity. The objective of this study was to analyze the hardfacing deposits on using a low carbon steel welding electrode with metal powders added to the weld pool. Four different samples were hardfaced applying a submerged arc welding setup with constant heat input. Single and three layers of hardfacing samples were welded using a standard martensitic electrode and compared to using low carbon steel electrodes with added metal powders. An optical emission spectrometer was used to obtain the chemical compositions of welded metal layers. A scanning electron microscope was used to characterize the metallurgical structures of deposits. SEM images of worn surfaces were also obtained. Microhardnessand abrasive testing were used to examine the mechanical properties of the hardfaced surfaces. The results showed that martensitic microstructures were obtained in the hardfaced deposits using a low carbon steel welding electrode with added metal powders. However, hardness and abrasive wear resistance of both single and three layers of hardfacing using low carbon steel welding electrode with added metal powder were below those achieved by welding with a standard martensitic electrode.