Metallurgical Studies Research Articles

Provision of iron objects in the southern borderlands of the Han Empire: a metallurgical study of iron objects from Han tombs in Guangzhou

It is widely acknowledged that the iron industry developed during the Han period led to the widespread distribution of iron implements, but how such iron implements were supplied to the peripheries, especially the southern frontiers within the Lingnan region where evidence of local manufacturing has not been widely found, remains unclear. This paper presents the results of analyses of iron objects from Han tombs in Guangzhou, which was a major center in Lingnan, as a means of shedding light on the iron supply system in the region. The metallurgical and SEM-EDS analyses identified cast iron, fined iron, solid-state decarburization of cast iron, and bloomery iron within the tested assemblage. Since evidence for local cast iron manufacturing has not yet been identified in Lingnan, the discovery of iron or steel objects made by the cast iron process suggested that a supply and transportation system for final products might have developed linking Guangzhou, and perhaps other centers in Lingnan as well, to iron production centers located outside the region. Meanwhile, the comparison of slag inclusions (SIs) in bloomery iron products from Guangzhou and smelting slag samples from the Guiping-Pingnan area of Guangxi, which were dated between the Han and Southern dynasties period, did not strongly support a link between the two areas. More studies are needed to further test this potential link. Nevertheless, through collective consideration of the available evidence, we would argue that the supply of iron daily items did rely on external sources, which suggests that a relatively well-developed transportation network might have existed between Lingnan and other parts of the Han Empire.

Musa acuminata (Green corrosion inhibitor) as anti-pit and anti-cracking agent for mild steel in 5M hydrochloric acid solution

• Dried peel of fruit of Musa acuminate was tested as green corrosion inhibitor. • Weight loss, Gasometric, electrochemical polarization and impedance spectroscopy (EIS) techniques were used. • SEM and metallurgical research microscopy study was carried out for the surface study. • Warburg impedance ( Z w ), faradaic current (I F ), capacitive current ( I c ), charge transfer Resistance, r ct and capacitive loop were observed. • 90.00% corrosion inhibition efficiency was observed for mild steel. • Musa acuminate proved to be anti-pit and anti-cracking agent for mild steel in acidic medium. Musa acuminata (Banana peels) was tested as green corrosion inhibitor (GCI) for controlling the problems of pitting and cracking corrosion of mild steel (MS) when comes in contact with 5 M HCl solution. Immersion test, gasometric, electrochemical polarization and impedance spectroscopy (EIS) techniques were employed for the corrosion study. SEM and metallurgical microscopy studies were carried out for the surface study of corroded specimens which confirms the adsorption of GCI molecules on MS surface. Surface study proves the formation of uniform, nonporous film over MS surface confirmed by decline in Faradaic current, increase in capacitive current ( I c ), charge transfer resistance, R ct (8.76 to 33.41 Ωcm 2 ), Warburg Impedance ( Z w ) and capacitive loop in Nyquist plot. High percentage corrosion inhibition efficiency i.e. 90.00% was observed for MS in presence of 4 g/L dried fruit peels of Musa acuminata in 5 M HCl solution. No evidence of pitting and cracking corrosion was seen on the surface of MS treated with Musa acuminate as GCI. Nyquist plots (EIS) of mild steel immersed in 5.0 M HCl.

Studies on effect of laser processed stellite 6 material and its electrochemical behavior

Laser cladding is one of the popular surface modification processes for providing enhanced wear and corrosion resistance to steels in various applications. In this article the investigations on laser cladding of Stellite 6 on EN8 steel has been reported. Stellite 6 is an extremely wear and corrosion resistant alloy and this study reports the corrosion behaviour of the cladded samples. Nine cladded samples were developed with the combination of different process parameters. Each sample was tested for corrosion behaviour using 1 M sulphuric acid solution. Metallurgic studies on the nine samples were conducted and the results have been reported. A clear correlation between the laser cladding parameters and the corrosion behaviour has been established.

Copper alloy production in the Warring States period (475-221 BCE) of the Shu state: a metallurgical study on copper alloy objects of the Baishoulu cemetery in Chengdu, China

Many bronze objects were unearthed in the capital of the Shu state in present-day Chengdu. However, only a few metallurgical studies have been carried out on those objects. This research attempts to study the alloy techniques and possible ore sources of 28 bronze objects recently excavated from the Baishoulu cemetery in Chengdu. Elemental composition and lead isotope ratios were measured, and metallographic observations were conducted. The results indicate that most objects were copper–tin–lead alloys with variable tin and lead content. The samples showed evidence of casting, as well as cold working and annealing techniques. The lead isotope data indicate that multiple lead sources were used in Baishoulu; however, the exact number is not yet known. Most of the lead sources in Baishoulu are the same as those in Zeng state bronze and Chu state bronze. In addition, some of the bronzes came from sources that were widely used in the Central Plains and surrounding regions. This new information aids in understanding the cultural interactions between Shu and other states. Moreover, some bronzes might have used local lead sources. Copper and tin sources were difficult to determine; however, the different trace elemental patterns between Baishoulu and Bayilu bronzes indicate different copper and tin sources might be used. Additionally, copper and lead may originate from different sources in the Shu state. Systematic data are necessary to disclose a possible metal source exchange network involving the Shu state in the Warring States period.

Adverse effects of Ni on the mechanical and corrosion-induced hydrogen embrittlement properties of ultra-strong giga steel used for automotive applications

Previous metallurgical studies have reported the beneficial effects of Ni addition to steels. In this study, however, the mechanical and corrosion-induced hydrogen embrittlement (CIHE) properties of medium C-based ultra-strong steel degraded with increasing Ni content. Steel samples with a higher Ni content had a higher fraction of undissolved cementite (Fe3C) in the martensite matrix, leading to a smaller prior-γ grain size and lattice parameter, and a lower tensile strength. Even at a higher austenitizing temperature, no significant change in the tensile strength of the sample with a higher Ni content was observed. This was attributed to the additional supply of C atoms into the lattice by the further dissolution of Fe3C. The tensile test at a slow strain rate did not reveal a proportional relationship between the Ni content and the CIHE indices, but an inflection point of the Ni quantity in the steel was noted. Based on the results, effective metallurgical strategies with respect to the optimal Ni contents and austenitizing conditions for the steel are proposed.

Comparison of metallurgical and mechanical properties of dissimilar joint of AISI 316 and Monel 400 developed by pulsed and constant current gas tungsten arc welding processes

Dissimilar weldments of AISI 316 and Monel 400 are extensively used in boiler feed water heaters where the weld roots are exposed to high pressure and hot corrosive environments. In this research, metallurgical and mechanical properties of dissimilar weldments of AISI 316 and Monel 400 obtained by pulsed current gas tungsten arc welding (PCGTAW) and constant current gas tungsten arc welding (CCGTAW) processes were compared. The heat input rate and filler wire were same in both welding techniques. Metallurgical properties are studied by employing optical microscope (OM) and scanning electron microscope (SEM). Mechanical properties of dissimilar weldments are determined by tension test and Vickers hardness. The metallurgical study has revealed fine grain structures with clear grain boundaries at the heat-affected zone in PCGTAW weldment. The ultimate tensile strength in PCGTAW and CCGTAW weldments was observed as 554 and 542 MPa, respectively. The ratio of yield strength to ultimate tensile strength is higher in PCGTAW weldment than CCGTAW weldment. The weldment developed by using PCGTAW technique has shown a higher microhardness value at HAZ of both the base metals than the weldment developed in CCGTAW technique.

Influence of laser weld shape on mechanical and fatigue behaviour of single lap laser welded joints

Traditional manufacturing processes, like arc welding and resistance spot welding, are still the main welding processes to join structural components used across the on/off-road vehicle industry. Due to the abundance of data, experiences and insights over the decades of usage, lot of fatigue design data has been generated for different joint geometries produced using these methods. The laser welding process has excellent capabilities to join thin sheet metal structures with minimum heat input resulting into lower deformation and improved productivity that offers significant benefit as compared to the arc and resistance welding processes. However, due to the agility of designing joint configurations and limited availability of understanding regarding the fatigue behaviour of laser welded joints, the need arises for the fatigue design data. Most of the research presents the use of straight linear shape laser welds and limited knowledge exist regarding the influence of shape of laser welds on mechanical and fatigue performance of the laser welded joints. The laser welded joints produce small notch like radius at the root of laser weld which could act as a stress raiser causing early crack initiation. For this work, C-shape laser weld has been selected as the geometric shape in comparison to the straight linear shape of laser weld produced on a series of single lap joints. Detailed fatigue experimental investigation has been carried out for linear and C-shape laser welded joints tested in 3 different orientations with respect to the applied cyclic load and several different R-ratio's and the results are compared. The metallurgical studies have been carried out to understand the failure mode and micro-hardness variations across the weld and heat affected zone. Further, the residual stress profiles have been compared for the C-shape laser weld with the linear welds using detailed X - Ray Diffraction based residual stress measurement.

Microscopic and Metallurgical Studies as a Function on Forensic Investigation of Electrical Fires

Electrical wires with melted ends showing beaded, drop-shaped, and pointed shapes are frequently encountered after fires that may provide useful information on the cause and development of the fire.Various methods have been studied for differentiating between primary arcing beads, (indicating arcing as the fire cause) and secondary arcing beads (indicating arcing as a result of the fire). There are few studies carried out on the melting globules produced due to fire heat. Also, in some major cases, primary arcing beads and secondary arcing beads are difficult to be identified by using one method. In this study, a full scheme of differentiating methods between simulated samples of melting globules, primary arcing beads and secondary arcing beads are processed with macroscopic investigation. The in-depth composition of carbon quantitative analysis and metallurgical analysis of these samples have been studied. The results of this study has proved that the real cases are compatible with simulated ones.

Improvement of tribo-mechanical properties of directionally solidified CM-247 LC nickel-based super alloy through laser material processing

Nickel-based super alloy was used in high mechanical stress applications due to their good creep resistance and oxidation behaviour. However, their undesirable tribological behaviour is the main technical issues in several applications. In this study, nickel-based super alloy CM-247 LC was laser processed in order to improve the tribo-mechanical properties. The metallurgical study was performed using optical microscopy (OM), scanning electron microscopy (SEM) with electron dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD). The optimized laser parameter shows a significant grain refinement with finely dispersed cell-like structure which enhanced the hardness up to 466 HV0.3. The laser-melted regions were showing with subtle variations in the distribution and shape of γ′ precipitates. XRD spectra were dominated from the γ and γ′ peaks. The maximum weaker reflections were consistent with the occurrence of MC carbides. The wear rates of laser-processed sample were reduced significantly while compared with substrate sample. The examined worn surface specifies that adhesion and abrasion was a significant wear. The phases like γ′ morphology, γ-γ′ eutectics and sizes can influence the tribological behaviour.

Temperature Distribution Study of Friction Stir Welded Aluminum Alloy 7075-T6 joints Reinforced with SiC Powders

Abstract Friction Stir Welding (FSW) is a unique process of joining two similar or dissimilar materials by generation of heat between two surfaces (tool shoulder and plate). The bonding made between two materials was achieved by a tool pin profile which makes the material to flow from the advancing side to retreating side. The main advantage of FSW is that during the welding process, the materials are joined with less heat and increased bond strength, due to reduced heat generation it results in better material properties when compared with other conventional welding processes. The experiments were conducted with SiC powders by varying the process parameters by keeping axial load as similar for all the trials. The tool used in the experiments is a high carbon steel D3, with a straight flat cylindrical pin. In the present work, we made an attempt to predict the theoretical temperature distribution for the joints made with FSW process using ANSYS. The temperature profiles were measured across different zones of welded sample for better understanding of temperature flow during the joining process. Metallurgical study was also carried outacross different zones and it is correlated with the theoretical temperature values for better understanding of process parameters and the effect / influence of adding SiC powders in material. From the results it is inferred that both temperature distribution and metallurgical study showed a good agreement due to its refined / coarse grain boundary development. The generation of higher temperature profile proves better mixing of SiC powders during the joining process. However, this work revealed that the process parameters and addition of SiC powders leads a major role in deciding the temperature profile across various zones of the FSW process.

Dissimilar laser welding of commercially pure copper and stainless steel 316L

This research work mainly focuses on the mechanical and metallurgical studies on commercially pure copper and stainless steel 316L dissimilar joints produced by laser welding technique. The following tests were conducted on the laser-welded specimen: the tensile test of weldments, Vickers microhardness, optical metallography, study of the chemical composition of the intermediate layer using EDS. During the tensile tests, the weld region is showing maximum yield and ultimate tensile strength.Moreover the percentage of elongation is higher in the weld region. Vickers microhardness results showed that the Copper base had the least hardness. Whereas in the weld section of Cu-SS316L region had the maximum hardness value. The SEM morphology illustrates the adequate presence of Cu and SS316L constitutes in the weld region.

Investigation on influence of solid lubricants over mechanical behavior of hybrid Al7075-SiC metal matrix composites

Al7075 alloy and its composites have a vast number of applications in the fields of automobile, aerospace, mechanical and marine industries. The study focuses on fabricating Al7075 metal matrix composites (MMC) fortified by Silicon Carbide micro-particles and various solid lubricants for applications in the development of pistons. The composition of the casted specimen has a weight of 90% of Al7075 alloy and 5% of SiC which has to be kept as constant followed by the variating type of solid lubricants (Graphite, Hexagonal Boron Nitride, and Molybdenum Di-sulphide) at a weight of 5% is added. Hybrid Al7075 composites were successfully contrived to be fabricated via the stir casting process. The casted specimens are machined for testing as per required ASTM standards. Static mechanical properties like tensile strength, compression strength and hardness of the fabricated composites are evaluated by conducting the experimental tests while its microstructural properties are analyzed via metallurgical microscopic studies and Energy Dispersive Spectroscopy (EDS). The results are compared to evaluate the best combination of solid lubricants for piston application. The results indicate that in all mechanical properties tested the Al7075 with 5% by wt. SiC and 5% by wt. graphite composite outperformed all other hybrid composites this might be due to the synergic effect of graphite and SiC with Al7075 alloy.

Synthesis, characterization and deformation of Al–4.5Cu/SiCp composites

Present study aims at producing silicon carbide particles (0, 3, 5 and 7 wt%) reinforced aluminium-copper based composites via stir casting route. The forging behavior of developed composites was studied by deforming the stir cast samples. Optical microscopy, Scanning electron microscopy with Energy dispersive spectroscopy and X-ray diffraction techniques were used to study the metallurgical changes in as cast and deformed samples. Microhardness and tensile strength of fabricated composites were measured to evaluate the mechanical behavior. Metallurgical studies revealed refinement and reduction in grain structure, which ultimately leads to improvement in mechanical properties of as cast and forged samples. Increment of 17.58 and 26.74% in microhardness for cast and forged specimens are reported. Ultimate tensile strength for cast specimens is reportedly improved by 28.39% with addition of ceramic particles in base matrix.

Assessment of parameters windows and tool pin profile on mechanical property and microstructural morphology of FSWed AA2014 joints

The role of optimized parameters in deciding the qualities of the friction stir welded joint of 2014 aluminium alloy in terms of the mechanical properties and microstructural features was investigated in this research. A wide range of process parameters viz: tool shoulder diameter, tool pin profile, plunge depth, tool rotation speed and welding speed were selected and their individual effects on the tensile as well as microstructural properties variations were studied in detail. Out of four various selected tool pin profiles the excellent mechanical as well as microstructural properties of the square pin (SQ) tool are due to the unique stirring effect by the pulsating action of the sharp edge of the pin and metal propagation process at the stir area with incorporation with the tool rotation as well as welding speed during the friction stir welding. The SQ pin tool of 24 mm shoulder diameter with a plunge depth of 0.06 mm and tool rotating at 815 rev/mm with welding performed at a speed of 63 mm/min yielded the best quality joint. The ultimate tensile strength is around 86% of the base metal (BM) with excellent metallurgical characteristics contributed by the 84% finer grains than the BM ensured from the detail microstructural analysis of the weld bead. The metallurgical study includes the variations in the grain size at the nugget zone with respect to the selected process parameters as well. Fractography of the welded specimen reveals a ductile and transgranular mode with cup and cone structures on the counterpart.

Necesidad de incrementar la carrera de Ingeniería Metalúrgica en las Universidades Peruanas

En el siguiente artículo, se analizan dos elementos fundamentales: la situación minera en el Perú, y la necesidad de incrementar los estudios de Ingeniería Metalúrgica. Ambos elementos deben estar indisolublemente ligados, ya que responden a necesidades económicas y sociales que cada vez se acentúan más. El trabajo está articulado en varias secciones que inician con un breve análisis histórico del papel de la educación y el desarrollo social, donde se insiste en el rol que juegan las universidades en este rubro. También se ofrecen comparaciones de lo anterior con otros países, tanto dentro del área como a nivel global, para llegar al siguiente objetivo: aportar informaciones necesarias para dar a conocer la urgencia de extender y perfeccionar las carreras universitarias de Ingeniería de Minas en el entorno nacional. Por otra parte, se hace énfasis en los conflictos sociales que lamentablemente se vienen originado y se mantienen en la población relacionada con la minería Para ello se tomaron como base algunos elementos aportados por la tesis de maestría Caminos de encuentro en el manejo de conflictos sociales en el sector minero: caso Cocachacra.

Influence of electrode force on metallurgical studies and mechanical properties of resistance spot welded dual phase (DP800) steel joints

Abstract The DP steels are attractive to automotive sectors due to the improved fuel efficiency, occupant’s safety and reducing the car body weight. The resistance spot welding (RSW) most appropriate eco-friendly process for sheet metal and white body car assemblies over fusion welding. The present research work analysis the impact of electrode force on mechanical and metallurgical characteristics of dual phase steel. In this investigation similar joint of DP 800 joints (lap shear and cross shear) specimen fabricated and tensile shear test was evaluated using a universal testing machine. Micro and macrostructure were evaluated optical microscope. The hardness was taken along the weld nugget using Vickers microhardness tester machine. The electrode force was varied at five levels (3.75 MPa to 4.75 MPa). The tensile shear strength is found to be increased with an increase in electrode force up to a certain limit and then it decreases. The microhardness survey revealed that peak hardness in the nugget zone and the hardness is lower in the HAZ. The softening of HAZ is mainly attributed to inter-critical heating during welding, which leads to weld failure.

Математическое моделирование процесса гидрометаллургической переработки демонтированной угольной футеровки алюминиевых электролизеров

The purpose of the paper is using the method of mathematical (physico-chemical) modeling to study hydrometallurgical processing of spent carbon pot lining of dismantled cathodes from aluminum reduction cells; using the method of thermodynamic analysis, which is based on the built model of the influence of caustic soda solution concentration (NaOH - Na 2 O ку ) and liquid and solid phases ratio to estimate fluorine extraction to solution. Mathematical modeling of fluorine leaching from spent pot lining samples is carried out on the basis of studying the physicochemical laws of the process using the «Selector» program complex based on the minimization of Gibbs energy and is widely used for metallurgical process study. The object of research is a sample of spent carbon pot lining of the aluminum reduction cell of RUSAL Krasnoyarsk OJSC. According to the X-ray phase analysis the fluorine-containing phases in the sample are cryolite Na 3 AlF 6 , chiolite Na 5 Al 3 F 14 , calcium fluoride CaF 2 , sodium fluoride NaF. Besides, Si, Fe, Mg, S, K, Ti are also found in the carbon-containing material under investigation. The behavior of the components of the spent carbon pot lining is evaluated in the process of alkaline processing under the action of the solution with Na 2 O ку concentration of 12.5, 17.5 and 25.0 g/dm 3 using the formed mathematical model. According to the model the best indicators of fluorine extraction into the solution (72.9-90.57%) have been achieved at the reagent concentration of 12.5, 17.5 g/dm 3 Na 2 O ку and the liquid to solid ratio of 10-12:1. The developed model allows to determine the amount of alkaline solution necessary for fluorine extraction and the optimal ratio of liquid and solid phases. The phase composition of cake and forms in which fluorine remains in solid residue (cake) are also determined.

Influence of Local Mechanical Parameters on Ultrasonic Wave Propagation in Large Forged Steel Ingots

In numerous applications, high strength forged steel requires uncompromising quality and mechanical properties to provide advanced performances. Ultrasonic testing are commonly used for material characterization to measure mechanical properties and for nondestructive testing to detect flaws or other features contained in metallic objects. In steel blocks of relatively small dimensions (at least two dimensions not exceeding a few centimeters), temperature and homogeneity are well controlled during the solidification. However, these parameters may become difficult to control during manufacturing of large objects. Forging and heat treatments are known to modify the microstructure and/or the grain size, therefore affecting elastic properties, and consequently, the ultrasonic inspection reliability. In this context, the relationship between ultrasonic group and phase velocity variations with local properties of a forged and heat-treated $$40{,}000~\mathrm {kg}$$ bainitic steel block manufactured in an industrial setting was investigated. The block was cut into a $$20~\mathrm {mm}$$ thick slice that was then divided into 875 parallelepiped samples. A subset was selected for ultrasonic measurements, metallurgical study, and chemical analysis. Ultrasonic phase velocity showed a strong correlation with grain size, whereas group velocity was shown to vary as a function of the Young’s modulus and the chemical composition. Tensile testing was performed to validate the Young’s modulus calculated from the ultrasonic group velocities.

Analysis on mechanical properties of gas tungsten arc welded dissimilar aluminium alloy (Al2024 & Al6063)

Abstract In this project dissimilar aluminium alloys (Al2024 & Al6063) are welded using tungsten inert gas welding in the butt joint with single V edge preparation. The welding is carried out with modifying three set of parameters such as current, gas flow rate and root gap. Welded materials is then subjected to various mechanical behaviour analyses such as tensile strength, hardness, corrosion test and microstructure analyze also carried out using scanning electron microscope for metallurgical study purpose. The main aim is to analyze how welding process parameters changes affect the mechanical behaviour of the aluminium alloys.

Prediction of heat affected zone and other mechanical properties of welded joints of HSLA A588-B of jet blast deflector

PurposeThe purpose of this paper is to predict and optimize the width of heat affected zone (HAZ) with better mechanical properties using suitable welding process and parameters for the fabrication of jet blast deflector (JBD) (high strength low alloy material of grade A588-B was used for fabrication) so that the JBD can sustain high exhaust parameters, because there are different welding zones formed due to the rapid cooling of weld metals. Out of the various zones of welding, HAZ remains the weakest zone in the entire weldment.Design/methodology/approachThe present work describes the modeling, simulation, Modeling of three-dimensional plate and mess generation process are carried out using ICEM CFD software. FLUENT 16.0 software is used for ANSYS simulation where various models are used for analysis and results are validated with the experimental outcomes. High strength low alloy plates are welded by using shielded metal arc welding and tungsten inert gas (TIG) welding processes with two different electrodes. Optical microscopy and scanning electron microscopy were used for metallurgical study. The mechanical properties were evaluated by tensile strength test, vickers microhardness test and impact test. The corrosion resistance was evaluated by performing the potentiodynamic polarization test.FindingsThe present study indicated for better mechanical properties and improved corrosion resistance for TIG welded joints with type 308 L filler.Practical implicationsIn aeronautical, defense, space and research organizations.Originality/valueIt can be shown from the scanning electron microscope technique that sound weld joint is produced with very good mechanical properties and joint also showed better corrosion resistance.