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The research material (type 347H alloy steel) has been characterized using optical microscopy and an EDS/SEM system. Annealing experiments have been conducted at temperatures range of 600–1050°C for 30 min–20 h by using an atmosphere-controlled furnace. Normal grain growth with intermediate grain size has been related to the favouring of creep resistance to recommend the material suitable for boiler tubes at operating temperatures up to 750°C for long duration. The kinetics of grain growth in the 347H has been shown to behave similar to a pure metal in the initial stage of annealing in the range of 0–30 min, beyond which the grain-growth process was found to be suppressed due to second-phase (NbC) particle-pinning and solute drag effects. The grain-growth exponent n is computed to be in the range of 0.117–0.313; the deviation from ideal kinetic behavior (n=0.5) has been scientifically justified. The activation energy for grain growth Qg, for the investigated alloy, has been graphically computed and validated. [ABSTRACT FROM AUTHOR]

The current state of GOST, which regulates the quality of the structure of steels and alloys, has significantly lagged behind the progress in the compositions and technologies for obtaining modern steels and alloys. Using the example of microstructural banding of steel, it is shown how to overcome this gap and bring the methodology developed in Russia to the level of interstate GOST.Other problems of quantitative evaluation of structural components of steels and alloys that can become the basis of industry, national and interstate standards are considered: microstructural heterogeneity of sheet metal; non-metallic inclusions in steel, including automation of GOST 1778-70, evaluation methods using the ASTM E1245 methodology and statistics of extreme values, as well as automatic particle analysis; central axial inhomogeneity of a slab; liquation strip in sheet metal; the proportion of coarse bainite blocks used to describe the properties of modern pipe steels; the structure of joints after multi-pass welding; the metallurgical quality of heat-resistant nickel alloys; the structure of alloys treated in a semi-solid state; the structure of pre-eutectic silumins; non-metallic inclusions in aluminum alloys (PoDFA method); the structure of high-strength cast iron; grain size distribution.

Abstract The automotive industry is turning to advanced high strength steels (AHSS) to reduce vehicle weight and increase fuel efficiency. However, the zinc coating on AHSS can cause liquid metal embrittlement (LME) cracking during resistance spot welding. To understand the problem, the severity of the cracking must be measured. Typically, this is done from the weld cross-section. Currently, there is no standard procedure to determine which plane through the weld must be examined to gauge cracking severity, leading to a variety of practices for choosing a cutting plane. This work compares the magnitude and variability of LME severity measured from the plane of exhibiting the most severe surface cracking to arbitrarily chosen planes. The plane exhibiting the most severe cracks had more and longer cracks on the cross-section than the arbitrarily chosen plane, resulting in a higher crack severity measurement. This higher absolute measurement increased the relative accuracy of the examination, allowing for fewer welds to be examined to precisely determine the effect of LME mitigation methods on cracking severity, how welding parameters affect LME cracking severity and the predicted LME affected strength of a particular weld.

Foreign metallographic standards are updated every 2–5 years and include an image analyzer, which was used for the first time more than 20 years ago. All valid modern standards are based on quantitative metallography methods, since visual estimation using the rating charts method contrary to direct stereological measurement by means of an image analyzer cannot provide unity of measurements. The status of State Standard GOST 1778–70 has been analyzed; until now, it is used in the revision of 1970, and high-priority problems of its improvement are formulated with allowance for the world experience of development of standard practice for determining the nonmetallic inclusions in steel. Herewith, the use of an automatic image analyzer should be available for all estimation methods described in State Standard GOST 1778–70 together with the visual estimation by methods Sh and manual measurements using methods K, P, and L. The practice of direct stereological measurements of the volume fraction, size, number, shape, and distribution of nonmetallic inclusions in steel should become one of the methods of State Standard GOST 1778. The names of rating charts (OT (DO = dot oxides), SN (NDS = non-deformable silicates), SKh (BS = brittle silicates), etc.) should be considered conditional, since optical metallography cannot estimate the chemical composition of the complex multiphase deoxidation products retained in the finished metal after secondary steelmaking. Interlaboratory round-robin tests, which are required for objective assessment during acceptance tests performed by the manufacturers and consumers of metal products, should become regular practice for provision of measurements unity. [ABSTRACT FROM AUTHOR]

Particle/grain size and their number density arecommonly characterized in two dimensions (2D) from planaroptical or SEM micrographs of polished samples. Accurateconversion of such quantities into the three dimensional (3D)values are necessary for prediction of material properties.Several contradicting conversion correlations are available inliterature. The main objective of the current works it to verifysome of them. For this purpose, geometrical (3D) models ofrandomly distributed mono-size spheres were constructed andsliced at different planes. The particle count and their size werevariated within the same control volume. The statisticalinvestigations of the date suggested a (2D)-to-(3D) conversionfactor of 1.152377 ± 0.009427, which is very close to some ofearlier works [A. N. Sinha, 1999].

Abstract Duplex stainless steels (DSS) are used in off-shore platforms due to their good properties resulting from the combination of two phases, namely austenite and ferrite. Secondary intermetallic phases, such as alpha prime (α´) and sigma (σ), which are harmful, can be formed at temperatures above 400 °C, or by a casting process. This study investigates the formation of sigma phase by thermal cycles running in a dilatometer (800 °C, 850 °C, 900 °C and 1,000 °C) for 1h, and at 850 °C for 3h and 7h. The optical microscopy of the DSS microstructure subjected to 800, 850 and 900 °C for one hour revealed a small fraction of σ phase with nucleation in the contour of ferrite/austenite phases, and tests by ferritoscope indicated a decrease (~4%) in a magnetic fraction (ferrite). However, samples subjected to dilatometric cycles at 850 °C for 3 hours showed an 18% decrease in the magnetic phase and quantitative metallography revealed a 33% fraction of σ phase precipitated in the ferrite phase. Tests conducted at 850 ºC for 7 hours indicated a high fraction of σ phase precipitated (approximately 50%), starting in the grain boundary, austenite/ferrite, and advancing in ferrite grain.

The microstructure of nodular cast irons is characterized by the presence of spheroidal graphite nodules. Metallographic tests may show irregular or degenerated graphite nodules that indicate a reduction in tensile strength of the material as well as its yield limit. This work proposes a computer vision algorithm to estimate the amount of degenerated graphite nodules as well as image analysis necessary to determine the relationship between this quantity of degenerated nodules and the loss of mechanical properties of the nodular cast iron. The proposed algorithm was tested using two cast iron samples, by measuring their microhardness and tensile strength. The results show that the amount of degenerated graphite nodules is inversely proportional to the limit of traction resistance. Sample "A", of the two samples tested, presented more degenerated nodules than "B" and a lower limit of traction resistance; therefore, it needs less strength to break. [ABSTRACT FROM AUTHOR]

In the paper, the authors present the history of stereology development in Poland from the 1930s until now. The authors concentrate on the talented scholars whose hard work, dedication, and enthusiasm contributed to popularizing stereological methods of quantitative assessment. From Hugo Steinhaus to now, the evolution and increase in popularity of stereology is briefly shown. The most significant achievements are described in more detail.

The article presents the results of tests of influence of the thermo-mechanical treatment parameters on the mechanical properties and microstructure of steel 23MnB4 for cold-upsetting. Measurements of the ferrite grains and pearlite colonies were conducted with the use of Met-Ilo program supplemented by additional procedures dedicated to structure analysis of ferritic-pearlitic steel. The process of rolling was conducted in simulation in semi-continuous finishing train arrangement with different temperature and cooling rate. Elaborated procedure of quantitative analysis of microstructure and conducted mechanical properties tests will be used during preparations of modified technologies of wire rod rolling to prepare products made of steel, the microstructure of which is characterised higher utility properties.

The paper presents the results of research concerning the influence of hot plastic working parameters on the deformability and microstructure of a Ni-Fe superalloy. The research was performed on a torsion plastometer in the range of temperatures of 900-1150°C, at a strain rates 0.1 and 1.0 s-1. Plastic properties of the alloy were characterized by the worked out flow curves and the temperature relationships of flow stress and strain limit. The structural inspections were performed on microsections taken from plastometric samples after so-called “freezing”. The stereological parameters as the recrystallized grain size, inhomogenity and grain shape have been determined. Functional relations between the Zener-Hollomon parameter and the maximum yield stress and the average grain area have been developed and the activation energy for hot working has been estimated.

The article presents the results of tests of influence of the thermo-mechanical treatment parameters on the mechanical properties and microstructure of steel C70D for wire rod. The methodology of quantitative description of pearlite morphology in steels with the use of the method on which a new computer program “PILS” - Pearlite Inter-Lamellar Spacing is based was presented. In order to verify the method, some quantitative tests of microstructure in samples after physical simulation of heat-plastic treatment were conducted on a deformation dilatometer device with diverse cooling rate for steel C70D. The process of rolling was conducted in simulation in continuous finishing train arrangement. Elaborated program and conducted tests will be used during preparations of modified technologies of wire rod rolling to prepare products made of steel, the microstructure of which is characterised with smaller interlamellar spacing.

The paper discusses the main stages of the automatic quantitative analysis of parameters of the'-dispersed phase in high-temperature polycrystalline nickel alloys and indicates their main difference from the standard methods of analyzing disconnected phases. We present 4 classes of characteristics of dispersed phase particles. These characteristics include the volume fraction, the dimensional parameters of particles and the spatial distribution parameters. For example, we calculated the parameters of the '-phase of a blade made of a heat resisting nickel alloy In792. The volume fraction and the equivalent diameter of the '-phase disperse particles increase in operation while their concentration decreases. These parameters of the '-phase change with changes in the mechanical properties of the alloy. The shape of the particles and the scatter of '-phase concentration change little in the process of operation.

In order to quantify ferrite content, three techniques, XRD, ferritoscope and optical metallography, were applied to a duplex stainless steel UNS S31803 solution-treated for 30 min at 1,000, 1,100 and 1,200 °C, and then compared to equilibrium of phases predicted by ThermoCalc® simulation. As expected, the microstructure is composed only by austenite and ferrite phases, and ferrite content increases as the solution treatment temperature increases. The microstructure presents preferred grains orientation along the rolling directions even for a sample solution treated for 30 min at 1,200 °C. For all solution treatment temperatures, the ferrite volume fractions obtained by XRD measurements were higher than those achieved by the other two techniques and ThermoCalc® simulation, probably due to texturing effect of previous rolling process. Values obtained by quantitative metallography look more assertive as it is a direct measurement method but the ferritoscope technique should be considered mainly for in loco measurement.

The paper discusses determination of materials porosity by the method of comparison defined in the standard GOST 9391–80 «Hard sintered alloys. Methods used for porosity and microstructure determination». The necessity and possibility of porosity assessment by the method of computer planimetry are shown. Using GOST 9391 standard scales the porosity was determined by means of the «Image SP» program for processing of images. It is shown that the error of determining the porosity is associated with a low quality of graphic material which also makes difficult determination of porosity by the method of comparison.

Non-metallic inclusions found in steel can affect its performance characteristics. Their impact depends not only on their quality, but also, among others, on their size and distribution in the steel volume. The literature mainly describes the results of tests on hard steels, particularly bearing steels. The amount of non-metallic inclusions found in steel with a medium carbon content melted under industrial conditions is rarely presented in the literature. The tested steel was melted in an electric arc furnace and then desulfurized and argonrefined. Seven typical industrial melts were analyzed, in which ca. 75% secondary raw materials were used. The amount of non-metallic inclusions was determined by optical and extraction methods. The test results are presented using stereometric indices. Inclusions are characterized by measuring ranges. The chemical composition of steel and contents of inclusions in every melts are presented. The results are shown in graphical form. The presented analysis of the tests results on the amount and size of non-metallic inclusions can be used to assess them operational strength and durability of steel melted and refined in the desulfurization and argon refining processes.

The paper presents the test results of microstructure and resistance to abrasion and erosive wear of single and double-layer coatings with arc-coated powder wires on the iron matrix. It was shown that adhesion of coatings is in the range of 14.39 - 24.72 MPa. The closed porosity of the coatings determined from SEM images is in the range of 0.69 - 2.45% and was significantly lower than the porosity determined from the images obtained from the optical microscope, which was 5.49 - 8.11%. The 95 MXC coating's hardness of the matrix was about 100HV0.05 higher compared to the AMI 100 coating matrix. The intensity of the erosion of AMI 100 coatings was lower than the intensity of the erosion of 95 MXC coatings. [ABSTRACT FROM AUTHOR]

In the paper, the authors present the history of stereology development in Poland from the 1930s until now. The authors concentrate on the talented scholars whose hard work, dedication, and enthusiasm contributed to popularizing stereological methods of quantitative assessment. From Hugo Steinhaus to now, the evolution and increase in popularity of stereology is briefly shown. The most significant achievements are described in more detail. [ABSTRACT FROM AUTHOR]

Simulated HAZ continuous cooling transformation (SH-CCT) diagram presents the start and end points of phase transformation and the relationships of the microstructures of HAZ, temperature and cooling rates. It is often used to assess the weldability of materials. In this paper, a weathering steel Q345C which is widely used in the bogies manufacturing was studied. The cooling times from 800C to 500C () were from 3 s to 6000 s, aiming to study the microstructures under different cooling rates. Different methods such as color metallography were used to obtain the metallography images. The results show that ferrite nucleates preferentially at the prior austenite grain boundaries and grows along the grain boundaries with a lath-like distribution when is 300 s. Austenite transforms into ferrite, pearlite and bainite with decreasing . Pearlite disappears completely when s. Martensite gradually appears when decreases to 30 s. The hardness increases with decreasing . The SH-CCT diagram indicates that the welding input and should be taken into consideration when welding. This work provides the relationships of welding parameters and microstructures. [ABSTRACT FROM AUTHOR]

The anelastic strain measured using tensile loading-unloading loops in pure Mg and in binary solid solutions of Mg-Al and Mg-Zn, with contents of 0.5, 2 and 9 at% Al and 0.8 and 2.3 at% Zn, was correlated with available data for the area fractions and number densities of twins, for applied strains of up to 3%. For pure Mg, no anelastic strain was observed up to about 4% area fraction of twins and at an applied plastic strain of ~1.7×10 −4 , after which it increased rapidly, levelling off at a plastic strain of ~1%. The alloys followed the same pattern, but from much smaller minimum area fractions of twinning, <1% for Mg-Zn, and ~2% for Mg-Al, at applied plastic strains of ~2.5×10 −4 and ~3.1×10 −4 , respectively. The anelastic strain saturated at a maximum value of ~0.002 for all alloys, save for the 9%Al for which it reached a much larger level (~0.004). The correlation with the number density of twins followed similar patterns. For a given alloy, the magnitude of the anelastic effect can be related to the applied stress in excess of that required to initiate microplasticity. The results are discussed in terms of the solid solution hardening and softening effects upon basal and prism slip in the dilute alloys, and of short range order upon slip and twinning in concentrated Mg-Zn. [ABSTRACT FROM AUTHOR]

Optical microscopy (OM) is often the first technique used to characterize surfaces of materials because of its simplicity and low cost. However, the information obtained by OM is usually limited to the geometry and spatial distribution of microstructural features. We present an advanced OM technique to perform quantitative microstructure analysis of polycrystalline metals and to assess partial grain orientation information from measurements of reflectance over a range of incident light directions. Our technique relies on the collection of a series of optical micrographs under controlled illumination conditions. We find a marked direction-dependence of reflectance and ascribe it to sub-micron facets on the surfaces of individual grains. These surface facets are, in turn, correlated to grain orientation. We automate our technique via digital processing and numerical analysis of micrographs, enabling it to generate a wealth of microstructure data while remaining simple to use and inexpensive to implement. [ABSTRACT FROM AUTHOR]

Gas metal arc welding (GMAW) is one of the most common methods used in the automotive industry to assemble car body parts of dissimilar high strength steels. Load bearing capacity of these components depends largely on the quality (e.g. absence of cracks, microstructure and mechanical strength) of weldments. In this context, GMAW, with the use of an austenitic steel filler, of a new advanced high strength TWIP sheet steel and a TRIP sheet steel is investigated in this research. Quality of butt weld beads being examined in terms of processing, microstructure, and mechanical properties. The grain coarsening and microstructural changes, as well as volumetric fraction of each phase, in the heat affected zone at the TWIP and TRIP side of the joint were also determined. The optimal heat input range needed to obtain good quality joints was determined, achieving ultimate tensile strengths over 585 MPa and fracture elongations over 9%. [ABSTRACT FROM AUTHOR]

There is a steady increase in the implementation of dual phase steels in stamped automotive components. Therefore, steel suppliers who develop dual phase steels are interested in predicting the microstructure-properties relationship for optimization of microstructural design. This goal is achievable by micromechanical modeling. The representative volume element (RVE) method has been a popular technique for micromechanical modeling of dual phase steels. It is generally considered that 2D modeling underestimates the flow curves and that 3D modeling predicts the experimental stress-strain curves more accurately. However, much of the research has focused on 2D modeling. This paper develops 3D micromechanical modeling of DP500 and bainite-aided DP600 steels by including statistical quantitative metallography data in the models. More than 3000 grains were analyzed in each steel. Hence, both volume fraction and morphology of martensite were statistically determined. This model predicted the ultimate tensile strength of these two dual phase steels with less than 0.5% error. [ABSTRACT FROM AUTHOR]

In order to quantify ferrite content, three techniques, XRD, ferritoscope and optical metallography, were applied to a duplex stainless steel UNS S31803 solutiontreated for 30 min at 1,000, 1,100 and 1,200 °C, and then compared to equilibrium of phases predicted by ThermoCalc® simulation. As expected, the microstructure is composed only by austenite and ferrite phases, and ferrite content increases as the solution treatment temperature increases. The microstructure presents preferred grains orientation along the rolling directions even for a sample solution treated for 30 min at 1,200 °C. For all solution treatment temperatures, the ferrite volume fractions obtained by XRD measurements were higher than those achieved by the other two techniques and ThermoCalc® simulation, probably due to texturing effect of previous rolling process. Values obtained by quantitative metallography look more assertive as it is a direct measurement method but the ferritoscope technique should be considered mainly for in loco measurement. [ABSTRACT FROM AUTHOR]

The polycrystalline cast IN100 superalloy was selected for this investigation. It is characterized by dendritic segregation. The major phases which are present in the IN100 superalloy are the ordered γ′ (Ni3Al-type) phase together with a disordered solid-solution γ matrix, and carbides. Additionally, a structural element occurs in the microstructure: colonies of (γ + γ′) eutectic. The main purpose of this work was to report on the following steps of the IN100 superalloy investigation: specimen preparation with microstructure revealing, image acquisition, computer-aided image analysis with detection of the investigated areas and their measurements. The volume fractions and chemical compositions of the phases were assessed using conventional metallographic and analytical electron microscopy techniques. [ABSTRACT FROM AUTHOR]

The article focuses on the importance of X-ray computer topography (CT) technique in research works. Topics discussed include use of the CT in material science community by acquisition of 3D images, numerical modeling of microstructures and tomography based imaging which includes phase imaging and crystal grain imaging. The methods and shortcomings of the CT for extracting topological parameters have also been discussed.

Abstract: The fracture characteristics of Al–Si based eutectic alloy are investigated in the unmodified and modified conditions under compression. The investigations are carried out at different strain rates and temperatures. Fracture of the alloy starts with eutectic Si particle fracture and modification plays an important role in particle fracture. The fraction of fractured particles is found to be always lesser in the modified condition than in the unmodified condition. Particle fracture increases with increase in strain. It is found that the Si particle fracture shows an increase with increase in strain rate and decreases with increase in temperature at 10% strain. Large and elongated particles show a greater tendency for fracture in the unmodified and modified conditions. Particle orientation plays an important role on fracture and the cracks are found to occur almost in a direction normal to the tensile strain imposed upon the particles by the deforming matrix in the unmodified alloy. The modified alloy shows a random distribution of fractured particles and crack orientation. The criteria of fracture based on dislocation pile-up mechanism and fiber loading explain the observed difference in particle fracture characteristics due to modification. The particle fracture for the modified alloy is also discussed in terms of Weibull statistics and the existing models of dispersion hardening. Particle/matrix interface decohesion is observed at higher strain rates and temperatures in the modified alloy. Dendritic rotation of 10° is also observed at higher strain rates, which can increase the amount of particle fracture. [Copyright &y& Elsevier]

This paper presents a methodology for assessing the phase composition and the results of structural stability tests of the sand-cast Mg–4Al–4RE alloy after annealing it at 175 and 250°C for 3000h. The microstructure was analyzed with optical, scanning electron, and transmission electron microscopy. The phase composition was determined with X-ray diffraction. The structure of the Mg–4Al–4RE (AE44) alloy is composed of large grains of α-Mg solid solution, needle-shaped precipitates of the Al11RE3phase, polyhedral precipitates of the Al2RE phase and Al10RE2Mn7 phase. After annealing at 175°C for 3000h, no changes in the alloy structure are observed, whereas after annealing at 250°C the precipitates of the Al11RE3 phase are found to be in the initial stages of spheroidization. The coarse-grained structure and unfavorable morphology of the intermetallic phases in the sand-cast AE44 alloy, which are caused by low solidification rates, result in low creep resistance up to 200°C and low mechanical properties at ambient temperature and at 175°C. [ABSTRACT FROM AUTHOR]

Under certain conditions, strain rate sensitive materials such as dual phase steels, show formability improvement under high strain rate forming which is known as hyperplasticity. In this research, two commercial dual phase steel sheets, DP500 and DP780, were formed under quasi-static conditions using the Nakazima test and under high strain rate conditions by electrohydraulic forming (EHF) into a conical die. Macro-strains, measured from electro-etched circle grids with an FMTI analyzer, showed remarkable formability improvement in EHF specimens. Micro-strains, i.e., the strains in the ferrite and the martensite, were calculated by quantitative metallography of more than 7000 ferrite grains and 10,500 martensite islands. The goal was to investigate the deformation improvement of the constituents under EHF. Around 20 and 100% deformation improvements were observed in ferrite and martensite, respectively. Furthermore, as a micro-mechanical modeling technique, correlation of the micro-strains with the macro-strains was investigated by applying the mixture rule. Results showed a reasonable correlation between the macro and micro-scale strains; however in banded microstructures, the strain in the martensite should be determined precisely for more accuracy. [ABSTRACT FROM AUTHOR]

A method to determine the basic parameters describing planar two-dimensional (2D) spatial arrangements of precipitates is presented. It is based on the observation that the total number of particles (precipitates), the total area, and total perimeter length of features examined in the microstructure at each step of dilation/erosion transformation uniquely depend on their initial 2D geometry (size, shape, and mutual spatial arrangements). These parameters have a clear physical interpretation such as the distribution of distances between precipitate boundaries that are measured along the shortest pathway between them. It is also argued that the network of the shortest pathway represents the dendrite and sub-grain boundaries. On this basis, the width distributions of the dendrites and sub-grains were determined. [ABSTRACT FROM AUTHOR]

Magnesium alloys due to their low density and high strength-to-weight ratio are promising material for the automotive and aerospace industries. Many elements made from magnesium alloys are produced by means of sand casting. It is essential to investigate impact of the applied mould components on the microstructure and the quality of the castings. For the research, six identical, 100x50x20mm plates has been sand cast from the Elektron 21 magnesium casting alloy. Each casting was fed and cooled in a different way: one, surrounded by mould sand, two with cast iron chills 20mm and 40mm thick applied, another two with the same chills as well as feeders applied and one with only the feeder applied. Solid solution grain size and eutectics volume fraction were evaluated quantitatively in Met-Ilo program, casting defects were observed on the scanning electron microscope Hitachi S3400N. The finest solid solution grain was observed in the castings with only the chills applied. Non metallic inclusions were observed in each plate. The smallest shrinkage porosity was observed in the castings with the feeders applied. [ABSTRACT FROM AUTHOR]

The effect of boron (between 0.06 and 0.11 wt%) on the microstructure, hardness and compression properties of cast Ti-6Al-4V was investigated. Compression properties were examined in the temperature range from room temperature to 1000°C. It was found that the addition of boron refines the as-cast microstructure in terms of prior beta grain size and alpha colony size. This microstructural refinement led to an increase in compressive yield strength from room temperature up to 700°C. Three different strain rates (0.001, 0.1 and 1 s) were evaluated during compression testing from which it was found that the compressive yield strength decreased with decreasing strain rate from 600°C up to the beta transus temperature. [ABSTRACT FROM AUTHOR]

The ASTM Standard for NiTi alloys does not specify the method to be used for the analysis of inclusions. Quantitative analysis is generally done by optical metallography with a computer program to measure size and area fraction. This study gives a comparison of quantitative analyses of inclusions by scanning electron microscopy using backscattered electron imaging (SEM-BEI) and quantitative analyses by optical metallography. Seven samples of 6.3-mm hot-rolled NiTi were evaluated. The coil samples were selected to exhibit a wide range of inclusion content. Each sample had a different Ni to Ti ratio corresponding to a different transformation temperature range (TTR) from A = −25 °C (Ni = 50.79 a/o) to A = +95 °C (Ni = 49.63 a/o). Quantitative analyses by optical and by SEM-BEI are in reasonable good agreement for maximum particle size and maximum area fraction. Both methods of analysis show that carbide and intermetallic oxide inclusion populations in VIM-VAR hot-rolled coil vary significantly in the amount and size of inclusions with the alloy transformation temperature. Therefore, an analysis of a larger number of samples at each TTR is needed to develop statistically precise data. All carbide inclusions were less than 12.5 μm and less than 1.0% area fraction in all the samples. Maximum size and area fraction of carbides decreased as TTR increased. Intermetallic oxide size and area fraction increased with increasing TTR Intermetallic oxides are fractured and separated from the matrix during hot working. However, stringering is very limited. The fracturing appears to happen in high TTR alloys but not in low TTR alloys. This dependence on TTR suggests that chemistry in or around the oxides affects their fracture behavior. [ABSTRACT FROM AUTHOR]

Abstract: This paper constitutes part of research conducted on the possibility of forming alloys based on intermetallic phases from the Fe–Al system via thermoplastic processing. Insufficient plasticity, which is an inhibitor of further development of these intermetallics as construction materials, makes the range of their applications limited. In the paper, an analysis is conducted of the influence of deformation parameters on the structure of an alloy of Fe–Al with the B2 type structure. Axi-symmetric compression tests were carried out at temperatures ranging from 600 °C to 1200 °C and at a deformation rate from 0.001 s1 to 10 s−1. Structural examination was carried out using light microscopy and transmission electron microscopy. A quantitative evaluation of the structure was made with the use of “Met-Ilo”. The results obtained will be used for the development of mathematical models determining the influence of deformation parameters on the alloy structure. [Copyright &y& Elsevier]

The steels of different carbon content were tested with respect to their microstructural and selected mechanical parameters variations. The original combinatorial method, based on the phase quanta theory, was applied in the quantitative metallographic assessment. Hence, the adequate geometrical parameters of steel microstructure were possible to be determined. Moreover, the selected mechanical parameters of the materials were evaluated using non-destructive and destructive methods. The results enabled to formulate some significant quantitative relationships between microstructure and mechanical parameters. [ABSTRACT FROM AUTHOR]

Abstract: The present research arises from the need to gain knowledge to control the precipitation of interdendritic dispersed graphite in mottled Nihard cast irons used in the outer ring layer of industrial duplex work rolls. Industry desires a volume fraction of 2.5–4% graphite, distributed homogeneously across the layer thickness, with a reasonably constant, high number of particles across the layer, with a predominantly short flake-graphite shape. The objective was to ascertain the role of metallurgical manufacturing parameters and their interaction with graphite precipitation in the layer, and in the outer and inner sections of the roll collar. These rolls, used in the finishing stands of hot strip steel mills, were processed by a double pour method using vertical centrifugal casting machines. Analysis was conducted using a fractional Design of Experiments (DOE) program consisting of 16 industrial trials based on the study of 7 manufacturing factors at 2 levels. The analyzed responses, obtained by quantitative metallographic techniques, were: the volume fraction, V V, number per unit area, N A, and the graphite morphology across the layer thickness. The results confirmed that an increase from 0.5 to 0.8kg/T of SiCaMn added as a bath inoculant in the ladle increased the fraction of precipitated graphite without affecting N A. An outstanding result was that the addition of 1kg/T of FeTi as a bath inoculant did not modify the amount of precipitated graphite but significantly affected the morphology, favouring the development of elongated graphite shapes. [Copyright &y& Elsevier]

The effect of plastic deformation on the grain boundary surface area per unit volume and edge length per unit volume is examined using two methods. The first by applying homogeneous deformations to tetrakaidecahedra in a variety of orientations and the second by using the principles of stereology. It is shown that the methods produce essentially identical results. It is now possible to calculate changes in the grain parameters as a function of a variety of deformations, for combinations of deformations, for complex deformations and for cases where it is not necessary to assume an idealised grain microstructure. [ABSTRACT FROM AUTHOR]