Metal Chemical Composition Research Articles

Effect of Electron-Beam Welding Speed on Weld Metal Mechanical Properties of 5V Titanium Alloy

The results of metallographic studies of 5V titanium alloy welds obtained with the range of electron-beam welding speeds from 20 to 120 m/h are presented. It was established that at all welding speeds some identical microstructure of a weld metal is formed, which can differ only in sizes and shapes of the primary crystals. The results of Vickers hardness, ultimate tensile stress and yield stress estimation by sample-free indentation methods are shown. The weld metal hardness distribution in the transverse direction is homogeneous while from the top to the root an increase in hardness values at all welding speed modes is occurred. It was also revealed that both the hardness and strength of the weld metal grow with the rising welding speed, herewith the increase in these properties in the top of the weld is more significant than in the root. According to the analysis of the interrelation between structure and mechanical properties it was concluded that the main reason of mechanical properties fluctuations is a change in the weld metal chemical composition as a result of the volatile components evaporation during welding.

CHANGES IN THE COMPOSITION OF NON-METAL INCLUSIONS AND CONTAMINATION STEEL D DURED BY ALUMINUM

Using optical and electron microscopy methods, the pollution of grade D carbon steel by nonmetallic inclusions in samples taken at the stages of metallurgical redistribution (EAF → LF → VOD → Casting). Metal contamination and chemical composition of non-metallic inclusions are determined. It was shown that deoxidation at the stage of production of the intermediate by aluminum leads to the formation of nonmetallic inclusions of corundum (Al2O3) in the metal melt, the proportion of which in total over all redistributions is 52%. Identification and assessment of contamination by non-metallic inclusions showed that subsequent stages of out-of-furnace treatment lead to a decrease in total pollution by inclusions. After evacuation and addition of Al and SiCa, corundum inclusions acquire a globular shape with a maximum size of not more than 6 μm. During solidification, the total contamination by non-metallic inclusions does not change, however. Contamination with silicate inclusions decreases, and the inclusion of corundum increases. The inclusions of corundum are irregular in shape, the high contamination with the inclusions of corundum is caused by secondary oxidation of aluminum during casting, as well as the ingress of products by overgrowing of the casting nozzle into the solidified continuously cast billet.

Uniform system for grouping of steels in welding manufacture by ISO/TR 15608

Recommendations to assign steel grades most commonly used in industry and energy of the Republic of Belarus to a specific group and subgroup of the international standard ISO/TR 15608 are presented. These recommendations were made on the basis of a comparative analysis of the base metal chemical composition and its mechanical properties, given in the national and foreign standards for sheet and pipe metal rolling. Analysis of mechanical properties have been included conditions of thermal and thermomechanical treatment of the base metal. The information presented in the article can be useful for a wide range of welding specialists in documentation development for welding processes (WPS, WPQR), issuing welders attestation certificates (qualification test certificate) and other technological documentation.

Diversification of the production and processing of pulverized wastes and ores based on the SER jet-emulsion unit

The principles of creating a self-organizing jet-emulsion reactor (SER) are considered, the role of dissipative structures in solving problems of controlling the metal chemical composition is shown. The technological scheme of the unit is presented, in which it is possible to process pulverized materials with a wide range of changes in chemical composition, including sludge, scale, poor pulverized ores and tailings.

Thermodynamic simulation of silicothermic chromium reduction process

Thermodynamic modeling of chromium reduction from the oxide system of the following composition was carried out, (wt %): 25.0 – 37.5 CaO, 25.0 – 12.5 SiO 2 , 25 CrO 3 , 5 FeO; 14 MgO, 3 MnO, 3 Al 2 O 3 . Silicon of ferrosilicon of FeSi20, FeSi45, FeSi65 grades was used as a reducing agent in amount of 110 % of stoichiometrically needed for iron, manganese and chromium reduction. Modeling was performed on HSC Chemistry 6.12 software package developed by Outokumpu (Finland). Calculations were performed using “Equilibrium Compositions” module in the initial nitrogen medium at total pressure of 0.1 MPa and in temperature range of 1500 – 1700 °С with step of 50 °С. The thermodynamic characteristics of chemical compound CrO (II) was introduced into the database. Thermodynamic constants of CaCr 2 O 4 compound presented in a database have been adjusted. Calculation results were presented in form of graphic dependences of change in degree of chromium reduction η Cr on temperature t, slag basicity (CaO)/(SiO 2 ), and silicon concentration in ferrosilicon [Si] FeSi . It was shown that increase in the process temperature from 1500 to 1700 °C at (CaO)/(SiO 2 ) = 2 reduces η Cr by 1.87, 6.04 and 7.38 % when using FeSi20, FeSi45 and FeSi65 reducing agents respectively. It was found that increase in (CaO)/(SiO 2 ) from 1 to 3 at temperature of 1600 °C leads to an increase of η Cr 2 by 17.3, 14.2 and 12.5 % using FeSi20, FeSi45, and FeSi65 respectively. Increase in silicon concentration from 20 to 65 % in [Si] FeSi ferrosilicon facilitates an increase of η Cr by 9.5, 5.9 and 4.2 % at slag basicity of 1, 2 and 3 respectively and at temperature of 1600 °C. Chemical composition of metal was determined. Results of thermodynamic modeling can be used to calculate degree of chromium reduction from recovery period slags of the argon-oxygen refining process in stainless steel production.

Prediction of the failure mode of automotive steels resistance spot welds

ABSTRACT In this study, the critical nugget size, at which the failure state in tensile shear test changed from the interfacial failure mode to the pull-out failure one, was estimated as a function of nugget and base metal hardness. The proposed approach could address the effect of various parameters involved in resistance spot welding process, such as sheet thickness, base metal chemical composition and physical properties of electrodes and sheets. The reliability of the present model was evaluated using independent experimental results. Based on the obtained results, the effect of steel composition on critical nugget diameter was found to be more important, especially for the sheets thicker than about 1 mm, whereas predicted nugget sizes by previous models could not guarantee the pull-out failure mode.

Влияние скорости ЭЛС на механические свойства металла шва титанового сплава 5В

The results of metallographic studies of 5V titanium alloy welds obtained with the range of electron-beam welding speeds from 20 to 120 m/h are presented. It was established that at all welding speeds some identical microstructure of a weld metal is formed, which can differ only in sizes and shapes of the primary crystals. The results of Vickers hardness, ultimate tensile stress and yield stress estimation by sample-free indentation methods are shown. The weld metal hardness distribution in the transverse direction is homogeneous while from the top to the root an increase in hardness values at all welding speed modes is occurred. It was also revealed that both the hardness and strength of the weld metal grow with the rising welding speed, herewith the increase in these properties in the top of the weld is more significant than in the root. According to the analysis of the interrelation between structure and mechanical properties it was concluded that the main reason of mechanical properties fluctuations is a change in the weld metal chemical composition as a result of the volatile components evaporation during welding

The chemical composition formation of the weld metal during welding over a layer of modifying granulated additive

ABSTRACT The formation analysis of the weld metal chemical composition during welding of bridge structures made of 10ХСND steel under the flux over a layer of granular modifying additive is given. It is shown that the chemical composition of the weld metal is determined not only by the composition of the materials involved in the welding process, but also by the trajectory of their delivery to the weld pool. The greatest effect of grinding grain in the weld metal takes place when the modifier enters the bath, bypassing the arc column. On the grounds of thermodynamic analysis it is shown that at welding over a layer of granulated additive, titanium dioxide modifying particles are captured by liquid metal flows, bypassing the process of dissociation. At the same time the refractory particles of the intermetallide compound TiAl2O5, which are the nuclei of the solid phase in the crystallization zone of the weld pool, are formed as a result of interaction with aluminium oxide coming from the flux. The relationship between the particle size of TiO2 in the composition of the granular additive and the size of non-metallic inclusions in the seam is established.

Prediction of the Ultimate Tensile Strength in API X70 Line Pipe Steel Using an Artificial Neural Network Model

An artificial neural network (ANN) model has been developed for the analysis and simulation of the correlation between the chemical composition and mechanical properties of high strength low alloy (HSLA) steel X70. The input parameters of the model consist of the base metal chemical composition (C, Si, Mn, the sum of Cr+Cu+Ni+Mo, the sum of Nb+Ti+V, carbon equivalent CEpcm) and the yield strength (YS). The outputs of the ANN model include the ultimate tensile strength (UTS) of the test material. Scatter plots, correlation coefficient (R) and mean relative error (MRE) were used to assess the performance of the developed neural network. Interestingly, the model output is efficient to calculate the mechanical properties of high strength low alloy steels, especially the ultimate tensile strength as a function of chemical composition and yield strength of the used material. The obtained results are in a good agreement with experimental ones, with high correlation coefficient and low mean relative error. The predictions accuracy of the developed model also conforms to the results of mean paired T-test.

Integrated Approach to Determine Operational Integrity of Crane Metal Structure

One of the elements limiting the crane life cycle and affecting the safety of its operation is a metal structure. Currently, there is no single scientifically-based approach to assess the operational integrity of crane metal structures. The paper deals with issues related to the development of an integrated approach to determine the operational integrity of crane metal structures, based on a combination of numerical methods of calculation (the finite element method and boundary states calculation) and magnetic coercive non-destructive control. The research of the influence of the metal chemical composition, its microstructure and the controlled elements thickness on coercive force values have been carried out. In order to take into account these parameters, it is suggested to use certificated experimental samples with variable cross sections. The practical value of the research is to apply the integrated approach that will eliminate the disadvantages of a separate method, complement these methods, increase the objectivity and accuracy of determining the operational integrity of crane metal structures.

Study of properties of cored wire based on ferrochrome gas-cleaning dust

Applying of wear-resistant alloyed coatings by build-up welding is one of methods to provide high operation properties of technological, metallurgical in particular equipment. Technologies of strengthening by direct alloying or reducing of alloying materials from oxide phases by reducing agent directly in the arc during building-up are most efficient ones. For build-up, cored wires are used frequently nowadays. A possibility to manufacture cored wires based on ferrochrome production gas-cleaning dust and powders of silicon, aluminum, and aluminum production gas-cleaning dust as reducing agents considered. Chemical composition and relation between cored wires components quoted. Manufacturing of 5 mm diameter wire accomplished at laboratory facility by running through draw plate. Duringestimation of efficiency of the manufactured cored wires application a regime of build-up was selected, study of chemical composition of built-up metal carried-out, wearing tests made, measuring of built-up samples hardness carried-out. Coefficients of chrome recovery coefficient at different relation between filling materials were calculated. Statistical processing of the study results accomplished statistical dependences of components content influence onthe built-up layer properties plotted. Study of the built-up showed, that chrome recovery in the built-up layer depends completely on the cored wire filling coefficient. At that under other conditions being equal, the hardness always correlates with the wear, and increase of chrome concentration results in reduction of the surface wear. Dependents of mass share elements comprising the cored wire content on built-up layer hardness and its wear resistance determined. The dependences obtained can be used for forecasting of builtup layer hardness and its wear resistance while built-up metal chemical composition varying.

Effect of steel casting speed mode on quality of continuously casted billet

The speed of billet withdrawal from a continuous caster (CC) mold has a decisive effect on the CC productivity. However, increase of the speed results in an increase of pollution of the CC metal by non-metallic inclusion and increase of surface defects of CC billet. Estimation of steel casting speed mode impact on the degree of different defects formation presented for long products CC billets, casted at a five-strand CC of radial type. Defects of CC billet from Ст3сп steel grade studied for a billet having section of 150×150 mm. The purpose of the study was to determine the degree of influence of withdrawal speed, metal chemical composition and billets cross section dimensions on billets quality. Array of industrial data of more than 550 billets studied, 80.4% of which were casted by an open stream and the balance – by a closed stream. As a result of the CC billets quality study it was confirmed, that during metal casting by an open stream the degree of evolution of form defect, like rhombic defects, internal and surface defects is higher comparing with those when casting by a closed stream. General tendency of increase of the CC metal pollution by non-metallic inclusions at the increase of billet withdrawal speed. The tendency is similar for both casting by an open and by a closed stream. However, during casting by an open stream the increase takes place rather evenly. During casting by a closed stream a sharp increase of billets with defects were observed at the billets withdrawal speed exceeding 2.4 m/min. Linear dependencies of billets withdrawal speed while casting by a closed stream on the degree of liquation cracks evolution and general strips, edge point pollutions and peripheral fine structure metal zone thickness determined. To improve the long products billets surface, casted by a closed stream, it was recommended to restrict the withdrawal speed of the billet from a carbon steel of general quality by the value of 2.4 m/min.

Depletion, technology, and productivity growth in the metallic minerals industry

Technological advancements dictate the productivity growth in all industries, including extractive ones. In the peculiar case of metallic mineral industries, this growth is also impacted by the natural variation in the metal content and chemical composition of the ore input, in the course of cumulative extraction and depletion of resources. Through a disaggregated treatment of productivity data achieved by using the input-output data on subprocesses of copper production and correlating them with input characteristics (ore grade), this study identifies and evaluates the impacts of the periodic changes in the natural input, as well as those of the technological progress, while reasonably controlling the influence of the other unrelated factors. This provides an objective assessment of the manner and extent of mitigation of the impact of the depletion-driven changes in the natural inputs of the said industry, through technological advancements. It reveals that the continuous and incremental developments in technology, successfully offset the detrimental effects of depletion on the copper sector productivity, often aided by the geological characteristics that changed to the miners’ advantage. However, the impact of depletion stands to outweigh the gains from innovative technologies, as soon as the ores breach a minimum threshold level of purity or chemistry. This study thus establishes the usefulness of productivity studies in estimating the impacts of depletion that may not proceed in strictly sequential and uni-directional manner. More importantly, it shows that the impacts are neither uniform nor linear and are not always detrimental to productivity growth. Though the study is primarily based on copper industry, the findings hold relevance for other metal industries too.

Alternative PWHT to Improve High-Temperature Mechanical Properties of Advanced 9Cr Steel Welds

Fil: Burgos, Ariel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologias y Ciencias de la Ingenieria "Hilario Fernandez Long". Universidad de Buenos Aires. Facultad de Ingenieria. Instituto de Tecnologias y Ciencias de la Ingenieria "Hilario Fernandez Long"; Argentina

Review of the Hard-Facing Technology Application for Reparation of the Given Parts in Various Branches of Industry

Abstract This paper deals with the problem of defining the optimal procedure for reparation of the machine parts of large dimensions and complex shapes. The procedure consists of establishing the causes of the part's damages, definition of the reparation technology, with selection of its parameters and ways of execution. The reparation is done by hard-facing, with heat treatment that consists of preheating, additional heating and the post hard-facing tempering. The process parameters' selection includes choosing the right filler metal(s), ways and order of depositing the hard-faced layers, ways of reaching and maintaining the preheating temperatures, checking of the base metal's chemical composition and mechanical properties and deciding on the post-process heat and mechanical processing of the executed hard-facing. The executed reparation of the forging hammer's mallet, presented in details, serves as an example how the reparation can successfully serve as a substitute for procuring the new part and thus producing the savings both directly in lower costs and indirectly in shortening the down-time of the damaged part operation.

Developing New Powder Wire for Surfacing Details which Works in the Wear Resistance Conditions

The paper presents the influence of chemical compositions and structure of the deposited metal on its hardness and wear resistance in abrasive-shock conditions. Metal Was deposited by the arc powder wire automatic welding. The studies have shown that increasing nikel contain to 0.65% in the surfaced steel and cobalt additive while reducing carbon contain to 0.17-0.23%, provides martensite and former austenite grain size disintegration. In consequence of multivariate correlation analysis, it was determined dependence to the hardness of the deposited layer and the wear resistance of the mass fraction of the elements included in the flux-cored wires of the system Fe-C-Si-Mn-Cr-Mo-Ni-V-Co. Obtained dependences could be used in predicting hardness and wear resistance of the deposited metal while changing welding metal chemical composition.

CORROSION RESISTANCE OF UNS S31803 STAINLESS STEEL WELDED JOINTS

The corrosion resistance of duplex stainless steel welded joints is affected by different parameters such as filler metal chemical composition, heat input, shielding gas composition and post welding heat treatment temperature. In most cases such parameters interact with each other so that it is very difficult to foresee their effect on corrosion resistance of welded joints without specific experimental tests. In this work the best combination of shielding gas composition and post welding heat treatment temperature that guarantees the corrosion resistance of the joint according to ASTM A932, method C, was found. Two shielding gases were tested during welding, Ar (100%) and a mixture of Ar (87%), He (10%) and N (3%), while the solution temperatures were 1050 °C and 1070 °C. It was found that only the samples welded with the mixture of Ar (87%), He (10%), N (3%) as shielding gas and solution heat treated at 1070 °C passed the corrosion test completely.

Stabilization of heavy metals in fired clay brick incorporated with wastewater treatment plant sludge: Leaching analysis

Wastewater treatment sludge or known as sewage sludge is regarded as the residue and produced by the sedimentation of the suspended solid during treatment at the wastewater treatment plant. As such, this sludge was gained from the separation process of the liquids and solids. This sludge wastes has becomes national issues in recent years due to the increasing amount caused by population and industrialization growth in Malaysia. This research was conducted to fully utilize the sludge that rich in dangerous heavy metals and at the same time act as low cost alternative materials in brick manufacturing. The investigation includes determination of heavy metal concentration and chemical composition of the sludge, physical and mechanical properties. Wastewater treatment sludge samples were collected from wastewater treatment plant located in Johor, Malaysia. X-Ray Fluorescence was conducted to determine the heavy metals concentration of wastewater treatment sludge. Different percentage of sludges which are 0%, 1%, 5%, 10%, and 20%, has been incorporated into fired clay brick. The leachability of heavy metals in fired clay brick that incorporated with sludge were determined by using Toxicity Characteristic Leaching Procedure (TCLP) and Synthetic Precipitation Leachability Procedure (SPLP) that has been analyzed by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results show a possibility to stabilize the heavy metals in fired clay brick incorporated with wastewater treatment sludge. 20% of the sludge incorporated into the brick is the most suitable for building materials as it leached less heavy metals concentration and complying with USEPA standard.

Changes in macroelements, trace elements, heavy metal concentrations and chemical composition in milk of Croatian spotted goats during different lactation stages

The research was conducted on days 60, 90, 120 and 150 during the lactation with the aim to determine the effect of lactation stage on the concentration of crucial elements and chemical composition in Croatian spotted goats' milk. Milk yield significantly decreased (from 1.15 to 0.76 kg/day), while the concentration of Ca, Mg, P, Zn and Mo in the milk of the goats significantly increased during lactation. The concentrations of Cr, Cd and Pb in milk were very low, with no significant deviations during lactation. The quality of milk from Croatian spotted goats is adequate compared with other breeds in the surrounding area of Croatia.

Mechanical and Acoustic Characteristics of the Weld and the Base Metal Machine Part of Career Transport

Currently, many industries use foreign-made machinery. There is no opportunity to purchase quality original spare parts for which machinery. Therefore, enterprises operating this equipment are looking for producers of analogues of various parts and assemblies. Quite often, the metal of such analog components turns out to be substandard, which leads to their breakdown at a much earlier date and the enterprises incur material losses.Due to the fact that the complex of performance characteristics and the resource of products are laid at the stage of their production, it is extremely important to control the quality of the raw materials. The structure, mechanical, acoustic and magnetic characteristics of metal samples of such destroyed details of quarry transport as hydraulic cylinders and detail “axis” of an excavator are investigated. A significant spread of data on the chemical composition of metal, hardness and characteristics of non-destructive testing is established, which gives grounds to recommend to manufacturers and suppliers of parts is more responsible to approach the incoming quality control. The results of the investigation of metal samples by destructive and non-destructive methods of control are compared, which showed that the spectral-acoustic method of nondestructive testing can be used to control the quality of the responsible machine parts under conditions of import substitution.