Metallurgical Studies Research Articles

Design and Construction of a Laboratory-Scale Direct-Current Electric Arc Furnace for Metallurgical and High-Titanium Slag Smelting Studies

A novel direct-current electric arc furnace (DC-EAF) was designed and constructed in this study for experimentally investigating high-titanium slag smelting, with an emphasis on addressing the issues of incomplete separation of metal and slag as well as poor insulation effects. The mechanical components (crucible, electrode, furnace lining, etc.) were designed and developed, and an embedded crucible design was adopted to promote metal-slag separation. The lining and bottom thicknesses of the furnace were determined via calculation using the heat balance equations, which improved the thermal insulation. To monitor the DC-EAF electrical parameters, suitable software was developed. For evaluating the performance of the furnace, a series of tests were run to determine the optimal coke addition under the conditions of constant temperature (1607 °C) and melting time (90 min). The results demonstrated that for 12 kg of titanium-containing metallized pellets, 4% coke was the most effective for enrichment of TiO2 in the high-titanium slag, with the TiO2 content reaching 93.34%. Moreover, the DC-EAF met the design requirements pertaining to lining thickness and facilitated metal-slag separation, showing satisfactory performance during experiments.

Metallurgical and wear study of MWCNT-reinforced h-AMMC fabricated through microwave hybrid sintering

Abstract The present work deals with the outcomes of a novel approach for developing a multi-walled carbon nanotube-reinforced hybrid aluminium metal matrix composite. Microwave hybrid sintering in combination with cold compaction of the powder metallurgy route was followed for the fabrication of composites. Microwave hybrid sintering was carried out using a microwave oven operating at 2.45 GHz frequency and 900 W power. For this purpose, Al5083 was used as the matrix material, and silicon carbide (15 wt.%) and multi-walled carbon nanotubes (0.5 wt.%) the reinforcements. The fabricated composites were then characterized by hardness, microstructure, and porosity. An investigation on the wear resistance of the base alloy and the conventional and microwave sintered composites followed this. The findings of the present study reveal the fact that the addition of carbon nano-tubes in the composite and the use of microwave energy over conventional sintering have a significant effect on the property enhancement of the developed hybrid composite.

Investigating the Effect of Si3N4 Reinforcement on the Morphological and Mechanical Behavior of AA2219 Alloy

The present investigation aims to investigate the mechanical, metallurgical and morphological study of Aluminium Alloy AA2219 reinforced with various percentage of Si3N4 (0,3,6 and 9) particles by high energy stir casting method. The structural characterization was carried out by XRD, EDAX, Radiography and SEM tests. Hardness, tensile and compression test reveals the mechanical behaviour of this material. Microstructure test reveals the uniform distribution of the reinforced material. Wear behaviour of the developed aluminium matrix composite (AMC) was investigated under different conditions of applied load, operation time and speed. The analysis carried out at room temperature for two different loads (20 N and 40 N) with varying two different operation times (30 mins, 60 min). The results showed that the mechanical properties, like tensile strength, compression strength and hardness exaggerated by the proportion of Si3N4 gift within the samples compared with base metal AL alloy. The surface morphology analysed through small structural analysis discovered that the reinforcement was uniformly distributed within the matrix. Worn surface of the test pieces was analysed by SEM and the surface morphology reveals that the wear rate reduced with the increase in reinforcement content.

Анализ современных исследований по кавитационной эрозии

Object and purpose of research. This paper discusses cavitation erosion on propeller blades. The purpose of this work is to review and analyse modern studies on cavitation erosion, as well as to apply these research results for better under-standing of cavitation damage risk on full-scale propellers. Materials and methods. The paper reviews recent studies on cavitation erosion, as well as the author’s own findings in cavitation erosion on full-scale steel propellers, analyzing the energy needed to create cavitation damage of recorded size. This energy was calculated as per the model based on the results of metallurgical studies discussing the effect of shot blasting upon steel properties. Comparison of these results with those obtained as per classic formulae for the collapse energy of cavita-tion bubble made it possible to estimate the conditions of cavitation erosion on propeller blades. Main results. The review of recent studies on cavitation erosion has shown that current progress in the technologies of experimental studies and computer-based simulations made it possible to considerably improve the knowledge about cavitation erosion process as compared to the level of the 20th century. This review shows that cavitation erosion studies followed three practically independent paths: experimental studies and computer-based simulation of flow around propeller blades with locali-zation of peaks for one or several criteria reflecting the intensity of cavitation energy fluctuations; the studies intended to esti-mate the pressure exerted by collapsing cavitation bubbles and emerging cumulative jets; and finally, the studies on the proper-ties of materials affected by cumulative jets and collapsing bubbles. At this point, it would be practicable to merge these three paths using the results of full-scale cavitation erosion analysis for propellers. KSRC findings in cavitation damage of full-scale steel propeller has shown that cavitation damage recorded in these studies might occur due to a certain combination between the required energy, bubble-blade interaction pressure and the size of affect-ed area on steel blade surface, and this combination, in its turn, might take place when cavitation bubbles consisting of vapour fraction with partial air content hit the blade surface and collapse. Conclusion. This paper shows the capabilities of modern research methods in obtaining new data on the inception mecha-nism of cavitation erosion. Still, to develop the methods for prediction of cavitation erosion (in particular, on propellers), it is necessary to merge the results obtained in different branches of cavitation studies. The basis for this merging could become a power-based analysis of cavitation processes, with help of the cavitation erosion model suggested in this paper and based on the similarity between cavitation erosion and shot-blasting.

Friction stir processing combined with incremental forming effect on AA2014-T6

ABSTRACT The present-study accustomed aluminum 2014-T6 alloy of 3 mm sheet as the work material for conducting the friction stir processing. The entire studies have been completed in two phases of work. In the first phase, the work material is subjected to single-pass and multi-pass friction stir processing for its structural embattlement. A multi-faceted tool called hexagonal tool pin profile was preferred to carry out the stir processing for both the single and multi-pass cases. An optimized stir processing parameters essentially tool-speed 1000 rpm, table-feed 60 mm/min and 2° pivot angle were selected to carry out the stir processing. In the second phase, the single-pass FSPed and multi-pass FSPed work samples along with an unprocessed base metal are subjected to single point incremental forming process for its performance assessment on formability. The effect of forming parameters on average thickness, wall angle, forming limit strains and surface roughness have been analyzed on the profile forming of a cylindrical cup. To characterize the nature of profile formed structures, metallurgical, grain analysis and micro-hardness studies have been carried out at different locations of the formed segments. Conforming to the results, multi-pass FSPed samples exhibit superior formability followed by single-pass and least in the unprocessed sample.

Joining and characterization of SS-430 using microwave hybrid heating technique

Purpose The purpose of this paper is to based upon the joining and characterization (mechanical and metallurgical) of ferritic stainless steel (SS)-430 using a microwave hybrid heating (MHH) phenomenon. Design/methodology/approach The preliminary experiments were conducted using nickel-based powder as interface material using a domestic microwave oven at a frequency of 2.45 GHz and 900 W power for 720 s. The processed joint was metallurgically characterized by means of X-ray diffraction, Energy-dispersive X-ray spectroscopy and Field emission scanning electron microscopy. Mechanical characterization was done by means of tensile and Vickers’ microhardness testing to check the hardness and strength of the joint. Findings The metallurgical study revealed that the microstructure and formation of numerous phases of Fe2Si3 accompanied by chromium and nickel carbides. The average hardness of 359 Hv at the center of the joint and 637 Hv around the boundaries of the joint was observed. The tensile strength of the joint was observed to 471 MPa with an elongation of 9.02%. The worn surface of the joint signifies the presence of plastic deformation and it was limited due to the presence of harder phases such as Ni3Si and Ni3C. Research limitations/implications The concept of microwave joining of metals is a very challenging task as the temperature can not be controlled in the inert atmosphere of the microwave. It has been also observed that at certain elevated temperatures, the material starts absorbing the microwaves; which is unknown. So, a more intensive study is required to overcome these kinds of limitations. Practical implications MHH technique can be used to process different materials such as ceramics, composites and polymers. SS-430 joined by microwave heating is highly corrosion resistive and has wide applications in refrigerators cabinet panels, dishwasher linings, chimney liners, lashing wires, etc. Originality/value As of the author’s best knowledge, no work has been reported on the joining of SS-430 which has huge potential in the industries. Also, no work has been reported on the characterization of microwave joined SS-430.

Sample preparation methods for optimal HS-AFM analysis: Duplex stainless steel

The contact mode high-speed atomic force microscope (AFM) operates orders of magnitude faster than conventional AFMs. It is capable of capturing multiple frames per second with nanometre-scale lateral resolution and subatomic height resolution. This advancement in imaging rate allows for microscale analysis across macroscale surfaces, making it suitable for applications across materials science. However, the quality of the surface analysis obtained by high-speed AFM is highly dependent upon the standard of sample preparation and the resultant final surface finish. In this study, different surface preparation techniques that are commonly implemented within metallurgical studies are compared for samples of SAF 2205 duplex stainless steel. It was found that, while acid etching and electrolytic etching were optimal for the low resolution of optical microscopy, these methods were less suited for analysis by high resolution high-speed AFM. Mechanical and colloidal silica polishing was found to be the optimal method explored, as it provided a gentle etch of the surface allowing for high quality topographic maps of the sample surface.

The Good ICT Design and Implementation Practices: Metallurgical and Radio-Astronomic Case Studies

This article is a herald of our Book 3 devoted to good ICT (Information and Communication Technology) design implementation practices gained during design and development of the Polish pioneering Computer Control Systems destined for the Steel-Bar Mill of a Warsaw Metallurgical Plant in Warsaw and for the Michelson Interferometer of the Nicolas Copernicus University in Torun. This article describes the basic premises valid for the Steel-Bar Mill system and the position assumed by the small 2-person design team to prove that such complex Computer Control Systems may be designed by local teams using home computer hardware and software systems. The description of Odra 1204 hardware and software available for the project is roughly mentioned together with the presentation of the performance evaluation system developed and run for the Steel-Bar Mill commissioning case and general as well as detailed conclusions. The final phase was mentioned and general conclusions were drawn. The ethical and HB assessment were developed and validated. Similar steps were mentioned and/or described for the Michelson Interferometer (Radio-Astronomic Dish Set planned for the Nicolas Copernicus University in Torun).

The Good ICT Design and Implementation Practices: Metallurgical and Radio-Astronomic Case Studies

This article is a herald of our Book 3 devoted to good ICT (Information and Communication Technology) design implementation practices gained during design and development of the Polish pioneering Computer Control Systems destined for the Steel-Bar Mill of a Warsaw Metallurgical Plant in Warsaw and for the Michelson Interferometer of the Nicolas Copernicus University in Torun. This article describes the basic premises valid for the Steel-Bar Mill system and the position assumed by the small 2-person design team to prove that such complex Computer Control Systems may be designed by local teams using home computer hardware and software systems. The description of Odra 1204 hardware and software available for the project is roughly mentioned together with the presentation of the performance evaluation system developed and run for the Steel-Bar Mill commissioning case and general as well as detailed conclusions. The final phase was mentioned and general conclusions were drawn. The ethical and HB assessment were developed and validated. Similar steps were mentioned and/or described for the Michelson Interferometer (Radio-Astronomic Dish Set planned for the Nicolas Copernicus University in Torun).

Microstructural and mechanical properties evaluation of dissimilar aluminum alloy and bronze joints using friction stir welding

The current research work discusses on the mechanical and metallurgical studies of process of joining aluminium alloy and bronze by using friction stir welding method. The dimensions of base and substrate materials is considered as 100 mm × 50 mm × 4 mm. H13 Tool Steel with conical shape is utilized as a tool and the diameter of shoulder is chosen as 40 mm. The various process parameters such as speed of welding, rotational speed of tool, tilt angle of tool and axial force are considered as the most influencing parameters in this work. The welding speed affects the mechanical properties of friction stir welding weldments. Hence, the experiments are carried out to evaluate hardness and tensile strength of the friction stir weld joint. The output of tensile test suggested that speed of the welding 20 mm/min exhibits a high tensile strength of 94.5 MPa. In addition, maximum hardness value of 75 BHN is attained at the welding 20 mm/min welding speed. From the experimental study, the optimal process parameters are found as 10 kN axial force, 1125 rpm rotational speed, 20 mm/min welding speed and 2° tilt angle of the tool. Further microstructure studies of FSW welded joint resulted that there is existence of reinforcement and even spreading of the particles all over the weld region.Selection and/or Peer-review under responsibility of International Conference on Sustainable materials, Manufacturing and Renewable Technologies (i-SMaRT 2021)

Study the mechanical properties of stainless steel & copper joint by tungsten inert gas welding

This article deals with the challenging dissimilar welding of Stainless Steel (SS) and Copper (Cu) and controlling welding process parameters of this welding for effective heat transfer application and power electronics application by Tungsten Inert Gas (TIG) welding. Two fillers ERCu and ERCuSi-A were used to join the Cu and SS dissimilar welding effectively. Joining Cu and SS is very critical during welding due to important metallurgical differences in the Ferrous-Cu system. This work mainly discussed the metallurgical effect and the control parameters of Cu and SS metal joining. The maximum tensile test fails at SS side at the location of heat affected zone (HAZ) and maximum value of 236 kgf/mm2 tensile strength has been achieved through this research work. The quality of this Cu and SS weld joint has been investigated by Scanning Electron Microscope image, optical microscopic image, hardness, bent test, tensile strength and impact strength. Welding current (A), voltage (V) and welding speed (mm/s) are taken as the control parameters to get the quality weld. From the quality weld the metallurgical studies were investigated.

A study of metallurgical and processing approach of additive layer manufacturing processes for metal tool components production

Additive Layer Manufacturing (ALM), also known as 3D printing technology process of manufacturing that refers models parts from wire, powder, or sheets in a process that produced layer-by-layer from computer aided manufacturing (CAM). This process enables to produce components via solid-state joining or melting process. In this paper, these methods for producing metal tool components production through processing study of ALM methods as heat transfer, processing defects, solidification, mechanical properties, solid-state precipitation and post-processing metallurgical study. The various metal ALM techniques are analysed and compared with analysis of their strengths and limitations. Most of the metal alloys fabricated and produced and developed for production of metal tool components, but recent development of ALM shows as a path for the producing and development of new materials for additive layer manufacturing processes.

Overview of metallurgical studies on weld deposited surface by plasma transferred arc technique

Research on plasma transferred arc (PTA) coatings has increased contemplation due to its augmented appropriateness which results from the advanced materials used in applications like mining, petroleum and power plant sectors. This article further broadens the research scope of investigation, by influencing metallurgical and processing aspects in accordance with the significance of microstructural changes. Martensitic formation with coarser structure, carbide phase formation and fine interdendritic eutectic matrix are the significant metallurgical aspects for an improved surface characteristic. Welding current, powder feed rate and travel speed, are the significant processing variables to achieve the microstructural changes like uniform dendritic growth, finer grain size, etc. The addition of alloying elements and heat treatment are the most observed processing conditions for the formation of precipitates and carbide phases. A schematic summary, the significance of processing variables, processing conditions and process modelling and simulation on metallurgical aspects have been enumerated in this paper. Further, critical comments and findings from in-depth review have also been discussed for the future scope. Hence, this review will be helpful to ascertain the relation among the microstructural evolution, the applicability of microscopic tools and the mechanical properties for the forthcoming researchers and the industrial persons.

Development of new medical Mg-Zn-Ca-Y alloy and in-vitro and in-vivo evaluations of its biological characteristics

Medical magnesium alloys show significant clinical potential as degradable orthopedic biomedical materials. In this study, a new medical magnesium alloy was fabricated and analyzed, with aim of providing a basis for the development of degradable magnesium alloys. Based on previous medical and metallurgical studies, a Mg-Zn-Ca-Y alloy with three different elemental ratios was designed, synthesized, and characterized. Their main composition was α-Mg, and they also contain other phase peaks, such as Mg24Y5. The differences in the contents of the alloy samples resulted in differences in their mechanical properties and biological properties. In general, alloy III exhibited the best properties. The hemolytic characteristics, cytotoxicity and antibacterial activity of the alloy samples were determined through in-vitro experiments while their histocompatibility and osteogenic properties were evaluated through in-vivo tests. The in-vitro tests showed that alloys II and III did not exhibit obvious hemolysis and cytotoxicity while the in-vivo experiments showed that these alloys exhibited good histocompatibility and osteogenic properties, with alloy III showing better characteristics than those of alloy II. Thus, alloy III should be highly suitable for use as an orthopedic internal fixation material.

Анализ причин разрушения деталей трассового изготовления

About 4 % of the connecting pieces used in the construction of oil pipelines in the 1950s–1970s were manufactured in the field. Despite the fact that in recent years the number of such parts has significantly reduced, failures associated with their lack of reliability occupy a noticeable share in the total number of failures in the system of oil trunk pipelines. The purpose of this work is to analyze the typical causes of failure of connecting parts using the example of a tee bend with a reinforcing plate. The authors carried out structural and fractographic studies of the defective structure. On the basis of information about the operating conditions and the actual characteristics of the bend metal, as well as data on the centers of destruction and the nature of crack propagation, computer modeling of the stress-strain state of the part was carried out. Based on the results of metallurgical studies and computer modeling, it was established that the cause of the formation of a through crack in the weld at the junction of the main oil pipeline and the reserve branch was excess stresses in the area of welding of the reinforcing plate to the branch, exceeding the tensile strength of the material of the tee branch pipe.

Investigation of metallurgical and mechanical behavior of forged aluminium alloy hybrid composites

The objective of this study was to fabricate Aluminium Alloy (AA8011) reinforcement such as 5 wt% of Zirconium Oxide (ZrO2) and 5 wt% of Aluminium Oxide (Al2O3) particles were agitated by stir casting route and then strengthened through Uni-direction (X axis), Bi-direction (X & Y axis) and Multi-direction (X, Y & Z axis) forging routes. During the stir casting process, the ZrO2 and Al2O3 reinforcements get incorporated within the matrix and are homogeneously dispersed to obtain Aluminum Matrix Hybrid Composites (AMHC). Further it was taken for uni, bi, multi - directional forging process, which enhances the mechanical and metallurgical behaviour of the Forged Aluminum Matrix Hybrid Composites (FAMHC). In which the mechanical properties like hardness, tensile and impact strength reveals that the multi-direction forged hybrid composite has preferably improved performance than the uni-directional and bi-directional forging. In metallurgical study the Scanning Electron Microscopy (SEM) revealed the homogeneous dispersion followed by the grain refinement of both the particles in the matrix and also it was evident from X-Ray Diffraction (XRD) analysis for the FAMHC samples. This technique also strengthens the hybrid composites due to equi-axial loading on the surface from three directions. On the whole, combined effect of addition of reinforcements through stir casting for fabricating the hybrid composites followed by multi– directional forging technique enhances the performance of the hybrid composite, thus making it a reliable alterative material for high strength applications in automobile and aeronautical industries.

Image-driven discriminative and generative machine learning algorithms for establishing microstructure–processing relationships

We investigate the methods of microstructure representation for the purpose of predicting processing condition from microstructure image data. A binary alloy (uranium–molybdenum) that is currently under development as a nuclear fuel was studied for the purpose of developing an improved machine learning approach to image recognition, characterization, and building predictive capabilities linking microstructure to processing conditions. Here, we test different microstructure representations and evaluate model performance based on the F1 score. A F1 score of 95.1% was achieved for distinguishing between micrographs corresponding to ten different thermo-mechanical material processing conditions. We find that our newly developed microstructure representation describes image data well, and the traditional approach of utilizing area fractions of different phases is insufficient for distinguishing between multiple classes using a relatively small, imbalanced original dataset of 272 images. To explore the applicability of generative methods for supplementing such limited datasets, generative adversarial networks were trained to generate artificial microstructure images. Two different generative networks were trained and tested to assess performance. Challenges and best practices associated with applying machine learning to limited microstructure image datasets are also discussed. Our work has implications for quantitative microstructure analysis and development of microstructure–processing relationships in limited datasets typical of metallurgical process design studies.

Machine learning for metallurgy II. A neural-network potential for magnesium

Interatomic potentials are essential for studying fundamental mechanisms of deformation and failure in metals and alloys because the relevant defects (dislocations, cracks, etc.) are far above the scales accessible to first-principles studies. Existing potentials for non-fcc metals and nearly all alloys are, however, not sufficiently quantitative for many crucial phenomena. Here machine learning in the Behler-Parrinello neural-network framework is used to create a broadly applicable potential for pure hcp magnesium (Mg). Lightweight Mg and its alloys are technologically important while presenting a diverse range of slip systems and crystal surfaces relevant to both plasticity and fracture that present a significant challenge for any potential. The machine learning potential is trained on first-principles density-functional theory (DFT) computable metallurgically relevant properties and is then shown to well predict metallurgically crucial dislocation and crack structures and competing phenomena. Extensive comparisons to an existing very good modified embedded atom method potential are made. These results demonstrate that a single machine learning potential can represent the wide scope of phenomena required for metallurgical studies. The DFT database is openly available for use in any other machine learning method. The method is naturally extendable to alloys, which are necessary for engineering applications but where ductility and fracture are controlled by complex atomic-scale mechanisms that are not well predicted by existing potentials.

Mechanical and Metallurgical Studies on Thixoextruded Al-Si Alloys

Thixoforming is a commonly known material processing technique that involves the fabrication of materials between solidus and liquidus temperatures. One of the prerequisites for this process is that the microstructure of the feedstock material must contain solid near-globular grains in a liquid matrix and a broad solidus-to-liquidus transition range. The aim of the present work is to study the application of Al-Si powder metallurgy (P/M) alloy in the thixoextrusion process and to evaluate the properties before and after extrusion. Al-Si P/M alloys were prepared for various Si compositions (1-7%) and Mg compositions (0.2-0.8%). The best among the Al-4Si and Al-4Si-0.6 Mg were selected based on hardness and density results. Differential thermal analysis revealed the solidus and liquidus temperatures to be 557 and 642 °C for Al-Si alloy and 564 and 636 °C for Al-4Si-0.6 Mg alloy, respectively. Compaction temperature and holding time studies have been carried out and the corresponding optimized parameters are found to be 550 °C and 60 min. Thixoextrusion was performed on the hot compacted preforms for three temperatures namely 560, 580 and 600 °C, respectively. An extrusion ratio of 4:1, strain rates of 0.1, 0.2 and 0.3 s−1 and die approach angle of 60° were used for the tests. Extrudates were divided into three regions namely front, middle and end parts to analyse its mechanical and metallurgical properties. Micrographic analysis revealed the presence of globular grains in the specimen. Hardness values showed a marginal increase from 45 to 60 HV for Al-4Si alloy and 42-80 HV for Al-4Si-0.6 Mg alloy.

Study of metallurgical changes and mechanical properties of dissimilar weldments developed by interpulse current TIG welding technique

This research manuscript compares the metallurgical changes and mechanical behavior of AISI 316 and Monel 400 dissimilar weldments developed by Interpulse TIG welding process with ERNiCrMo-3 and ER316 filler wires. Metallurgical aspects are envisioned by using optical and scanning electron microscopes. Mechanical behavior of welded joints were studied by conducting tensile and microhardness tests. Metallurgical study has shown that the ERNiCrMo-3 filler weldment divulged completely with austenitic phase structure at the weld zone. Also, at the HAZ of Monel 400 clear grain boundaries with fine grains were observed. The mechanical properties corroborated that the weld strength of ERNiCrMo-3 weldment was found better than the ER316 weldment. Microhardness on the weldment made of ERNiCrMo-3 filler has shown higher values than that of base metals. Weldment made by ER316 was observed to fail near the interface of Monel 400 under tensile test due to the existence of micro-pores and partially melted zones. Further, the metallurgical and mechanical properties are compared with that of the weldment developed by TIG welding process.