Showing papers in "Journal of Materials Engineering in 1989"
TL;DR: In this paper, the effects of grain size on magnetic properties of nonoriented electrical steel sheets were investigated at the commercial power of frequency (50 Hz), and it was shown that core loss, magnetic induction, and ac permeability were optimal at large grain diameters in the irreversible magnetization range, and at small grain sizes in the rotation magnetisation range.
Abstract: The effects of grain size on magnetic properties of nonoriented electrical steel sheets were investigated at the commercial power of frequency (50 Hz). The permeability, magnetic induction, and core loss of test specimens were optimal at their intermediate grain sizes. (LC) core loss W15/50 of Epstein specimens was minimum at a grain diameter of approximately 150 μm, regardless of the silicon content. A study of the relationship between magnetic properties and grain size of ring specimens showed that core loss, magnetic induction, and ac permeability were optimal at larger grain diameters in a weak magnetic field and at smaller grain diameters in a strong magnetic field. It was found that magnetic induction and ac permeability tended to improve at large grain diameters in the irreversible magnetization range and at small grain diameters in the rotation magnetization range.
104 citations
TL;DR: In this paper, a discussion of the corrosion mechanisms at work on magnesium under various environmental conditions is presented, and the role of base metal impurities is investigated, as well as the strengths and limitations of more traditional corrosion protection methods are discussed.
Abstract: Some physical properties of magnesium are reviewed. A discussion of the corrosion mechanisms at work on magnesium under various environmental conditions follows. The role of base metal impurities is investigated. The strengths and limitations of the more traditional corrosion protection methods are discussed. Several modern non-paint surface treatments and still largely experimental corrosion resistant surface modification techniques are assessed. Magnesium based composites are of special interest, in particular the magnesium-graphite fiber composite system. The latter has been identified as unique for certain space satellite applications by virtue of its very favorable physical properties. Its principal drawback, susceptibility to severe corrosion in most environments, is discussed. Some consideration is devoted to preserving the desirable properties of Gr-Mg composites while incorporating interface modification or substitute reinforcement materials. Finally, recommendations are made for successfulab initio design of corrosion protection into magnesium based components in light or recent research developments.
102 citations
TL;DR: In this article, the commercial scale production of Fe-6.5wt% Si sheet has been successfully developed and the details of the magnetic properties of Fe 6.5% Si sheets and some applications to electric devices are described.
Abstract: The commercial scale production of Fe-6.5wt% Si sheet has been successfully developed. Fe-6.5wt% Si sheets ranging in thickness from 0.1 to 0.5 mm can be manufactured in coil form with a maximum width of 400 mm. The following magnetic properties have been achieved.
Fe-6.5wt% Si sheet should be used extensively as an electric and electronic material, owing to its own supreme soft magnetic properties. For example, this sheet is good for use in motor cores or high frequency transformer cores, supreme magnetic shields, and so on. The details of the magnetic properties of Fe—6.5wt% Si sheet and some applications to electric devices are described.
58 citations
TL;DR: In this paper, the authors presented a new material, amorphous Fe-B-Si alloys, that exhibit the largest sensor figures of merit ever measured. And when the material is used as a strain gage, a figure of merit of 4 x 105 is achieved.
Abstract: We present a new material, amorphous Fe—B—Si alloys, that exhibit the largest sensor figures of merit ever measured. In particular we show that when the material is used as a strain gage, a figure of merit of 4 x 105 is achieved [1]. This is three orders of magnitude larger than that of any presently used strain gage. We will show how other sensors, torque sensors for example, can be constructed.
27 citations
TL;DR: In this article, the principal corrosion mechanisms in refractory metal-alkali systems are dissolution, mass transfer, and impurity reactions, and static corrosion studies have verified that the systems are basically compatible.
Abstract: The principal corrosion mechanisms in refractory metal-alkali systems are dissolution, mass transfer, and impurity reactions. In general, niobium, tantalum, molybdenum, and tungsten have low solubilities in the alkali metals, even to very high temperatures, and static corrosion studies have verified that the systems are basically compatible. Loop studies with niobium and tantalum based alloys have not indicated any serious problems due to temperature gradient mass transfer. Above 1000 K, dissimilar metal mass transfer was noted between the refractory metals and iron or nickel based alloys. The most serious corrosion problems encountered are related to impurity reactions associated with oxygen.
27 citations
TL;DR: In this paper, the combined action of wear and corrosion processes was investigated on Cr and TiN thin films ion plated onto 304 stainless steel and M 50 steel, respectively, and the wear process was found to affect the materials' corrosion behavior by lowering the corrosion potential, extending the activation polarization region, and increasing the passive current density.
Abstract: The combined action of wear and corrosion processes was investigated on Cr and TiN thin films ion plated onto 304 stainless steel and M 50 steel, respectively. A new laboratory technique was used to study the simultaneous effects of mechanical and electrochemical parameters during a sliding wear process in a corrosive environment. The wear-corrosion studies were conducted in 0.1M NaCl using potentiodynamic polarization scans. The wear process was found to affect the materials’ corrosion behavior by lowering the corrosion potential, extending the activation polarization region, and increasing the passive current density. The degree to which these changes occur is a primary function of the oxide stability and the repassivation kinetics. The wear process produced a smaller effect in both ion plated films when compared to their steel substrates. The TiN film in particular remained intact after wear-corrosion testing and showed a current density three to six orders of magnitude less than M 50 steel. The TiO2 stability, adherence to the ion plated film, and high rate of formation, together with low film roughness, are the main parameters producing the high wear-corrosion resistance in this system.
23 citations
TL;DR: In this paper, a texture analysis performed on recrystallized Zircaloy-4 sheet using x-ray diffraction techniques, crystallite orientation distribution function (CODF) analysis using pole figure intensity data, predictions on mechanical anisotropy and formability using CODF and appropriate plasticity models, and experimental characterization of mechanical aisotropic mechanical properties using grid technique.
Abstract: Mechanical properties of Zircaloys, like many other hexagonal close-packed (hcp) metals, are sensitive to the textures developed during fabrication processes. These alloys exhibit highly anisotropic mechanical properties, a thorough knowledge of which is needed for selecting materials with good formability characteristics as well as for the predictability of inservice behavior. This paper describes texture analysis performed on recrystallized Zircaloy-4 sheet using x-ray diffraction techniques, crystallite orientation distribution function (CODF) analysis using pole figure intensity data, predictions on mechanical anisotropy and formability using CODF and appropriate plasticity models, and experimental characterization of mechanical anisotropy using grid technique. In addition, the localized plastic flow analysis, which gives the upper limits on the strains that the material can withstand without failure, is also considered. The texture based model predictions of the anisotropy parametersR andP and the formability parameterB show an excellent agreement with the experimental measurements. Analysis of the true stress-strain behavior indicates that necking in this material starts much earlier than the maximum load, and the localized plastic flow analysis gives the maximum strains along the rolling (RD) and transverse (TD) directions of the sheet that the material can be subjected to without the initiation of diffuse or local necking. The material parameters obtained in these analyses control the formability during thermomechanical processing, and the inservice behavior of the material.
22 citations
TL;DR: In this paper, the impact properties of a 5Cr-2W-0.25V steel and a 9Cr-1MoVNb and 12Cr- 1MoVW steels were determined.
Abstract: Chromium-molybdenum ferritic (martensitic) steels are leading candidates for the structural components for fusion reactors. However, irradiation of steels containing molybdenum or niobium in a fusion environment will produce long-lived radioactive isotopes that will lead to difficult waste disposal problems. To alleviate the waste disposal problem, ferritic steels are being developed that are analogous to conventional Cr-Mo steels, but with molybdenum replaced by tungsten and niobium replaced by tantalum. Experimental steels containing 0.1% C, 2 1/4 to 12% Cr, 0 to 2% W, 0 or 0.25% V, and 0 or 0.07% Ta were produced. Charpy impact properties were determined. A 5Cr-2W-0.25V steel and a 9Cr-2W-0.25V-0.07Ta steel had the best impact properties. The impact properties of these two steels as well as those of a 9Cr-2W-0.25V and a 12Cr-2W-0.25V steel were as good or better than the properties of similarly heat treated conventional 9Cr-1MoVNb and 12Cr-1MoVW steels.
21 citations
TL;DR: In this article, the final microstructure of the die-upset magnet, consisting of closely stacked flat Nd2Fe14B grains separated by a Nd-rich boundary phase, is produced by a combination of grain boundary sliding and grain boundary migration.
Abstract: Fully dense and aligned Nd-Fe-B permanent magnets can be prepared from melt-spun amorphous ribbons by a two-step process involving hot compaction and hot deformation. It is the latter processing step that produces alignment. During hot deformation, the randomly oriented and equiaxed Nd2Fe14B grains change to platelet shaped grains such that their crystallographicc axes lie normal to the flat surfaces. The final microstructure of the die-upset magnet, consisting of closely stacked flat Nd2Fe14B grains separated by a Nd-rich boundary phase, is produced by a combination of grain boundary sliding and grain boundary migration. Factors such as temperature, strain rate, grain size, etc. which affect these processes also affect deformation and alignment. Processing optimum die-upset magnets involves optimizing such variables as composition (to obtain maximum percentage of magnetic phase while retaining an appropriate intergranular phase to aid in grain boundary sliding and migration), alignment (to obtain maximum remanence) and microstructure (to provide for domain wall pinning sites).
20 citations
TL;DR: In this article, a tensile adhesion test was applied to two layer coatings (NiCrAlY or NiCrAlZr bond coat with a yttria stabilized zirconia ceramic overlay) which are tested in tension per- pendicular to the surface.
Abstract: Tensile adhesion tests (TATS) which are normally utilized for industrial quality control procedures have been used for research purposes to examine failure mechanisms of plasma sprayed coatings. This work is applied to two layer coatings (NiCrAlY or NiCrAlZr bond coat with a yttria stabilized zirconia ceramic overlay) which are tested in tension per- pendicular to the surface. The mechanical behavior of the bond coat and ceramic overlay were not measured separately. However, the specific component of the coating which sustains the major deformation is related to the failure locus and enables an empirical determination of the bond coat and ceramic overlay deformations to be postulated. It has been determined that adhesive failure within the bond coat exhibits greater failure strain than cohesive failure of the ceramic overlay. This view lends support to the commonly accepted understanding of these intermediate coatings being highly compliant. The absolute extension exhibited by failures which occur only through the ceramic coating (i.e., cohesive failure) is greater than that of adhesive failure because the ceramic coating is much thicker than the bond coat. The stress vs. extension data can be expressed in terms of stress vs. strain, and hence the modulus of the coating components approximated to be about 100 MPa. This value is several orders in magnitude lower than that previously reported in the literature and the technical reasons for this discrepency are discussed.
16 citations
TL;DR: In this paper, new ternary additions capable of imparting ductility to high saturation cobalt-iron alloys, such as 0.2wt% tantalum or niobium, are reported.
Abstract: The paper reports work on new ternary additions capable of imparting ductility to high saturation cobalt-iron alloys. Additions as low as 0.2wt% tantalum or niobium are found to be effective and also beneficial in terms of a higher saturation compared with the conventional 2% vanadium alloy. The magnetic and tensile properties of a 49Co-0.35Ta-Bal. Fe alloy after heat treatment at varying temperatures are reported in detail. The properties are compared with the 2% vanadium alloy, and while the ac losses are higher, the dc characteristics of the tantalum alloy are found to be superior.
Journal Article•
TL;DR: In this paper, a synthese des donnees and analyses relatives a l'emploi de paliers en ceramique for les turbines a gaz dans l'industrie aeronautique.
Abstract: On presente une synthese des donnees et analyses relatives a l'emploi de paliers en ceramique pour les turbines a gaz dans l'industrie aeronautique (alumine, carbure de titane, carbure de silicium, nitrure de silicium, vitroceramique cristallisee). On etudie l'effet des contraintes de contact, des proprietes elastiques, de la temperature, de la vitesse de rotation, on discute de la generation de chaleur, de la lubrification, du montage et de la fabrication
TL;DR: In this article, a brief review of the work published in the last 30 years in Fe-Co-V alloys is presented, and new routes for research on FeCo-X and Fe-co-V-X alloys are pointed out.
Abstract: The development of advanced motors and generators for airspace and special power applications requires the use of soft magnetic materials which have high mechanical strength. In the search for these high strength soft magnetic alloys, a great number of investigations have been done in the last decade, and as a consequence, important advances have been obtained. The Fe-Co alloys present excellent magnetic properties and have been indicated as candidate materials for these power applications. In this work a brief review of the work published in the last 30 years in Fe-Co-V alloys is presented, and new routes for research on Fe-Co-X and Fe-Co-V-X alloys (X is an alloy element) are pointed out.
TL;DR: The mechanism of corrosion protection for Nd-Fe-B magnets by surface treatment with H2CrO4 is believed to be (a) removal of the nucleation site for corrosion by chromic acid etch, and (b) formation of a protective film on the surface by chromate conversion as mentioned in this paper.
Abstract: The corrosion behavior of Nd-Fe-B magnets varies depending on the alloy composition, surface condition, and corrosion environment and temperature. The kinetics of corrosion of Nd-Fe-B magnets in deionized water at room temperature are usually a gradual weight decrease, while those in an autolcave environment are generally a two-step weight change: first, an incubation step; second, linear weight loss. The corrosion products in deionized water are mainly Fe (OH)2, while those in an autoclave are mainly Nd(OH)3. Magnets surface treated with H2CrO4, HF, H3PO4, or their combinations exhibit a significant improvement in corrosion resistance compared with untreated magnets. The mechanism of corrosion protection for Nd-Fe-B magnets by surface treatment with H2CrO4 is believed to be (a) removal of the nucleation site for corrosion by chromic acid etch, and (b) formation of a protective film on the surface by chromate conversion. The combination of surface treatment and alloying with elements such as Dy will further improve the corrosion resistance of the magnet.
TL;DR: In this article, the authors describe the rapid solidification technology process applied to the processing of different neodymium-iron-boron alloys to prepare permanent magnets, which can be used for a wide variety of applications by injection and compression molding.
Abstract: Rapid solidification technology offers outstanding prospects for new cost effective engineering materials with superior properties. The authors describe the rapid solidification technology process applied to the processing of different neodymium-iron-boron alloys to prepare permanent magnets. The materials thus processed have high and low coercivities with differing temperature coefficients for use in varied applications. One of the main advantages of preparing magnets by rapid solidification processing as compared to sintering is that the magnets can be ground without degradation in magnetic properties. The ground powder thus obtained is anisotropic and can be used for a wide variety of applications by injection and compression molding. Energy products of 15-17 MGOe have been achieved by compression molding techniques and energy product of 20 MGOe is possible using this powder.
TL;DR: In this paper, the vacuum work function of chemically vapor deposited (CVD) rhenium was investigated and it was concluded that residual gas pressure was responsible for conflicting work function data.
Abstract: The vacuum work function of chemically vapor deposited (CVD) rhenium was investigated. The thermionic emission technique was used in order to obtain high temperature data. Data were collected as a function of temperature and time, and the total pressure was recorded. X-ray analysis showed that the rhenium was preferentially deposited with the 0001 planes approximately parallel to the emitting surface. The effective work function data were compared with the results of Campbell et al. [1]. It was concluded that the residual gas pressure was responsible for conflicting work function data.
TL;DR: In this paper, the effect of annealing temperature on grain size, maximum permeability and coercive force of 47.5% nickel-iron alloys with different sulfur contents was investigated.
Abstract: The effect of annealing temperature on grain size, maximum permeability and coercive force of 47.5% nickel—iron alloys with different sulfur contents was investigated. Alloys with lower sulfur content require lower annealing temperature to attain specified values of magnetic properties. The experimental results show that the coefficient 3y/Ms, wherey is the domain wall energy andMs is the saturation magnetization, can be used to correlate both coercive force and maximum permeability to grain size.
TL;DR: In this paper, the mechanical properties of the as-cast material and the thermally aged material were investigated and a conclusion was made that cast duplex stainless steel is sufficiently tough, even in the aged condition, to resist crack initiation and propagation under expected nuclear pump service conditions.
Abstract: Cast duplex stainless steel, grade CF-3, used in nuclear pump applications, was thermally aged at 400° C to induce an embrittling phase transformation, thereby simulating long term exposures at 280° C (536° F). The mechanical properties of as-cast material and the thermally aged materials were subsequently investigated. Fracture toughness, Charpy VNotch (CVN), tensile, precracked CVN, nil-ductility transition temperature, and hardness tests were performed on these materials. Tests were run as a function of temperature and loading rate. The as-cast structure of this duplex stainless steel is extremely tough, but thermal aging causes a decrease in upper shelf fracture toughness parameters and absorbed Charpy energy, and a marked increase in transition temperature. However, even the most severely aged material (14406 hr/400° C) appears to possess excellent upper shelf values, although the transition temperature shift is to a relatively high temperature. A conclusion is that cast duplex stainless steel is sufficiently tough, even in the aged condition, to resist crack initiation and propagation under expected nuclear pump service conditions.
TL;DR: In this paper, core loss, permeability, magnetostriction, insulation coating, strip flatness, thickness and width variations, camber, space factor, and physical characteristics are considered.
Abstract: A transformer core requires a low loss, high quality material for good performance. Items affecting the core performance include: core loss, permeability, magnetostriction, insulation coating, strip flatness, thickness and width variations, camber, space factor, and physical characteristics. Consideration of these items will help to improve the core performance.
TL;DR: In this paper, the degradation of three Inconel 617 Alloy Thermal Energy Storage capsules filled with eutectic fluoride salts LiF-MgF2-KF, LiF Mg F2-NaF and LiF F F 2 NaF were analyzed.
Abstract: The corrosion degradation of three Inconel 617 Alloy Thermal Energy Storage capsules filled with eutectic fluoride salts LiF-MgF2-KF, LiF-MgF2-NaF and LiF-MgF2 were analyzed. The ultrahigh purity fluoride salts were previously sealed inside the Inconel capsules under controlled processing conditions and thermally cycled in vacuum over a temperature differential of 200 K near 1000 K for 10,000 hr. It was determined that the microstructural degradation is minimal but some aluminum from the alloy may have been displaced into the salt. Comparisons are made with previously reported equilibrium calculations and a semiquantitative diffusion model is presented to support the possibility of diffusion control over the corrosion. The results indicate that Inconel 617 may be a suitable material for fluoride salts in thermal energy storage applications.
TL;DR: The phase coexistence in the Fe-Nd binary system has been investigated by metallography, x-ray diffractometry, electron microprobe analysis, and differential thermal analysis.
Abstract: Phase coexistence in the Fe—Nd binary system has been investigated by metallography, x-ray diffractometry, electron microprobe analysis, and differential thermal analysis. The technique of diffusion couples also has been used. The Fe17Nd2 compound is peritectically formed at 1185° C and the eutectic reaction is L → Fe17Nd2 + Nd*, occurring at 670° C; the Fe2Nd phase was not found. A double thermal arrest is observed at the eutectic temperature and its origin is not well understood yet.
TL;DR: In this paper, the results of thermal and ion bombardment induced reactions at the interface between the chromium layer and graphite substrate have been studied under an ultra high vacuum (UHV) condition at temperatures between 400 and 750° C. The experimental results are discussed in terms of grain boundary diffusion, ion induced segregation, atomic mixing, and metastable carbide formation.
Abstract: Thermal and ion bombardment induced reactions at the interface between the chromium layer and graphite substrate have been studied, by means of Rutherford backscattering spectroscopy (RBS), auger electron spectroscopy (AES), and reflection of high energy electron diffraction (RHEED) techniques, under an ultra high vacuum (UHV) condition at temperatures between 400 and 750° C. It is found that thermal annealing at temperatures above 650° C for ∼ 15 hr forms the polycrystalline chromium carbide layer of a single Cr7C3 phase on graphite. On ion bombardment of category I, where the linear range of ions is smaller than the thickness of the chromium carbide layer, it is found that the chromium carbide layer is transformed into an amorphous phase but the carbon concentration in the chromium carbide layer is unchanged. On the other hand, on ion bombardment of category II, where the peak of range distribution is located at the interface, it is found that the Cr7C3 phase is tranformed into a Cr3C2 phase, and moreover the normalized sputtering yields of Cr are more reduced than those in the category I, for the same removal rate of carbon atoms at the surface. The experimental results are discussed in terms of grain boundary diffusion, ion induced segregation, atomic mixing, and metastable carbide formation.
TL;DR: In this paper, the role of the Ga addition which enhances coercivity in Nd/sub 14/Fe/sub 79.75/ die upset magnets, metallurgical investigations using Auger electron spectroscopy (AES) and energy-dispersive x-ray spectra-transmission electron microscopy (EDX-TEM) were done.
Abstract: To understand the role of the Ga addition which enhances coercivity in Nd/sub 14/Fe/sub 79.25/B/sub 6/Ga/sub 0.75/ die upset magnets, metallurgical investigations using Auger electron spectroscopy (AES) and energy-dispersive x-ray spectroscopy-transmission electron microscopy (EDX-TEM) were done. Ga has a tendency to be condensed in the Nd rich phase (higher than 2 wt%) and Ga content in the matrix is around 0.2 wt%. The Ga solution in these phases seems to strengthen the pinning force defined at the interface of the matrix and the Nd rich phase. To improve thermal stability further, the Co substitution for Fe in Nd/sub 14/Fe/sub 79.25-{mu}/Co/sub {mu}/B/sub 6/Ga/sub 0.75/ ({mu} = 0 to 20) magnets was investigated. The Co substitution up to {mu} = 20 does not decrease coercivity, while for sintered magnets the Co substitution decreases coercivity very markedly. The irreversible losses for {mu} = 0 and 7.5 after exposure at 180{sup 0}C are over 10% and under 5%, respectively. Using pulverized Nd/sub 14/Fe/sub 71.75/Co/sub 7.5/B/sub 6/Ga/sub 0.75/ die-upset magnets, anisotropic bonded magnets (compression molded) with 15 MGOe of (BH)/sub max/ and 19 kOe of /sub i/H/sub c/ were obtained. The irreversible loss is under 5% after exposure up to 140{sup 0}C. The results ofmore » these studies are detailed in this paper.« less
TL;DR: In this article, the effect of silicon implantation on the microhardness of sapphire and on the modulus of rupture of implanted polycrystalline alumina was also measured and is reported.
Abstract: Ion implantation of silicon ions into sapphire and polycrystalline alumina followed by heat treatment resulted in the precipitation of mullite. A dose of 1 × 1018 Si+ /cm2 followed by a heat treatment at 1400‡ C produced an interlocking mullite surface layer with a needle morphology which was identifiable by x-ray diffraction (XRD). The lower thermal expansion coefficient of mullite compared to alumina produces a compressive surface layer on cooling from the annealing temperature and is evidenced by observations of Vickers indentations. Annealing at 1400‡ C resulted in a 30% increase in fracture toughness for sapphire and more importantly, an increase of 30% was also observed for polycrystalline alumina substrates. The effect of silicon implantation on the microhardness of sapphire and on the modulus of rupture of implanted polycrystalline alumina was also measured and is reported.
TL;DR: Rapid solidification technology is a significant new approach to the production of metallic materials as discussed by the authors, and the application of that technology to magnetic materials has resulted in properties far better than those of comparable materials produced by more traditional processing methods.
Abstract: Rapid solidification technology is a significant new approach to the production of metallic materials. The application of that technology to magnetic materials has resulted in properties far better than those of comparable materials produced by more traditional processing methods. Much of the developmental work has been guided by metallurgical insights. For Fe base metallic glasses, the considerations include glass formation, mechanisms and kinetics of devitrification, and magnetic stability. Crystallographic ordering, which prevents conventional processing of desirable high solute content Fe—Si and Fe—Si—Al alloys, can be circumvented by rapid solidification.
TL;DR: In this paper, the reaction of metallic sodium with a large excess of sodium and potassium nitrate salt mixtures was studied at temperatures up to 873 K. The reaction was exothermic, producing sodium nitrate, sodium oxide, and nitrogen gas.
Abstract: The reaction of metallic sodium with a large excess of sodium and potassium nitrate salt mixtures was studied at temperatures up to 873 K. Reactions were carried out in 316 stainless steel (316SS) vessels to ascertain the extent of corrosive action that would take place if a leak developed in a sodium-to-nitrate heat exchanger employed in a solar thermal, central receiver power plant. The reaction was exothermic, producing sodium nitrate, sodium oxide, and nitrogen gas. A black residue of chromium depleted steel was also found. Heat exchanger damage due to a pinhole leak was estimated by injecting sodium through 316SS capillary tubes immersed in the salt mixture at 873 K. To determine the extent of damage to adjacent material, experiments were designed so that the sodium, which was injected through the capillaries, impinged on INCOLOY® 800 or 316SS targets.
TL;DR: In this article, the compositions of the second phase particles in grain oriented 3%Si-Fe have been studied by using the scanning transmission electron microscope (STEM), and the changes in the composition of the particles through the processes have also been studied.
Abstract: The compositions of the second phase particles in grain oriented 3%Si-Fe have been studied by using the scanning transmission electron microscope (STEM). Second phase particles have been extracted from hot rolled band, primary recrystallized samples, and samples at the early stage of secondary recrystallization. The results of x-ray microanalysis have indicated that copper is a key element in the formation of second phase particles in both conventional and high permeability grain oriented 3%Si-Fe, and thus plays an important role in primary grain growth inhibition. The changes in the composition of the particles through the processes have also been studied.
TL;DR: In this paper, the effect of cold reduction on the magnetic properties of low silicon electrical steel was investigated in the laboratory and in the mill and the results showed that core loss is independent of percentage of cold reductions for both mill and laboratory processed samples.
Abstract: The effect of cold reduction on the magnetic properties of a nonoriented, low silicon electrical steel was investigated in the laboratory and in the mill. Both the hot band gauge as well as the cold band gauge were varied to obtain various cold reductions ranging from 57 to 80%. Magnetic test results from coil centers show that, at a given cold band gauge, core loss is independent of percentage of cold reduction for both mill and laboratory processed samples. Relative permeability, on the other hand, shows a functional relationship with the amount of cold reduction and the relationship varies with cold band gauge. For all cold band gauge, permeability initially improves with increasing cold reduction and this improvement is partially attributed to an increased coiling temperature due to hot band gauge increase. It is also observed that permeability measured from coil ends is substantially lower than that from coil center due to coil end effects. Possible cause and remedy of coil end effects are discussed.
TL;DR: In this paper, a mesh supported fiber metal acoustic medium FM 827 was designed for use in gas turbine auxiliary power unit exhaust environments without supplemental cooling and exposure testing was conducted under conditions which simulated auxiliary power units operation.
Abstract: FELTMETAL fiber metal acoustic materials function as broad band acoustic absorbers. Their acoustic energy absorbance occurs through viscous flow losses as sound waves pass through the tortuous pore structure of the material. Exhaust gas noise attenuation requirements are reviewed. Their selection process for higher performance materials is discussed. A new FELTMETAL fiber metal acoustic material has been designed for use in gas turbine auxiliary power unit exhaust environments without supplemental cooling. The physical and acoustic properties of mesh supported fiber metal acoustic medium FM 827 are discussed. Exposure testing was conducted under conditions which simulated auxiliary power unit operation. Weight gain and tensile strength data as a function of time of exposure at 650{sup 0}C (1202{sup 0}F) are reported. Fabrication of components with fiber metal acoustic materials is easily accomplished using standard roll forming and gas tungsten arc welding practices.
TL;DR: In this article, the microstructures of the steel at various tempering temperatures have been determined and the mechanical properties at room temperature along with fractographic characteristics of the tensile and impact test specimens have been evaluated.
Abstract: Overtempering characteristics of Mn-Cr steel used in retaining rings have been considered. The microstructures of the steel at various tempering temperatures have been determined. Mechanical properties at room temperature along with fractographic characteristics of the tensile and impact test specimens have been evaluated. The metallographic results show that massive carbide precipitation begins at 450‡ C onwards on stress relief. The mechanical test results indicate that the determination of the percentage reduction in area in tensile test, energy absorbed in impact test, and both tensile and impact fractographs give an accurate picture of the health of a retaining ring forging.