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Showing papers on "Pearlite published in 2001"


Journal ArticleDOI
TL;DR: In this paper, the microstructure of a pearlitic steel wire with a higher strain as much as 5.1 with tensile strength of 5,170 MPa was characterized.

243 citations


Journal ArticleDOI
TL;DR: In this paper, it is shown that the surface layer of a railway track transforms during exploitation into a nanocrystalline Fe-C alloy and the mechanism of the nanostructure formation is discussed.
Abstract: The microstructure of the surface layer of railway tracks is investigated. It is shown that the surface layer of the rail transforms during exploitation into a nanocrystalline Fe–C alloy. The mechanism of the nanostructure formation is discussed. It is shown that the transformation of pearlite to the nanostructured Fe–C alloy layer is caused by the heavy plastic deformation at the wheel–rail contact zone. The transformation of the microstructure of the surface may take place at rail–wheel contact temperatures less than 230°C and its mechanism is similar to that taking place during mechanical alloying.

239 citations


Journal ArticleDOI
TL;DR: In this article, a mechanistic model for the micro-endmilling process is developed that explicitly accounts for the different phases while machining heterogeneous materials, and it is shown that frequencies in the cutting force signal higher than those that can be explained by the kinematics of the process can be explain by considering the multiple phases in the material.
Abstract: A mechanistic model for the micro-endmilling process is developed that explicitly accounts for the different phases while machining heterogeneous materials. It is shown that frequencies in the cutting force signal higher than those that can be explained by the kinematics of the process can be explained by considering the multiple phases in the material. Experiments are performed on two compositions of ductile iron, pure ferrite and pearlite workpieces. These experiments show that the nature of the variation in the ductile iron cutting force signals can be attributed to the mixture of the phases. Additionally, simulation studies show that the frequency component of the variation is related to the spacing of the secondary (ferrite) phase and the magnitude of this component is determined by the size of the secondary phase particles.

169 citations


Journal ArticleDOI
TL;DR: In this paper, a method for determining both the fraction ferrite and the fraction pearlite is presented, in which the temperature range of the transformation is divided into a ferrite-forming range and a pearlite-formation range.
Abstract: Dilatometry is a useful technique to obtain experimental data concerning transformation kinetics in ferrous alloys. This technique is commonly used in cooling experiments to study the austenite decomposition of hypo-eutectoid steel grades. In the standard analysis of the dilatation signal there are two factors that are normally neglected. During the pro-eutectoid ferrite formation the austenite enriches in carbon, resulting in a non-linear temperature dependence of the specific austenitic volume. Furthermore, the specific volume of the formed ferrite is considerably different from that of the formed pearlite. In total not taking into account these two effects can lead to an error in the determined fraction ferrite of up to 25%. A method is presented that takes into account the two above-mentioned factors. In order to determine both the fraction ferrite and the fraction pearlite, in the analysis the temperature range of the transformation is divided into a ferrite-formation range and a pearlite-formation range. Two possible criteria for this division are discussed, and it is shown that the choice does not have an essential influence on the results.

156 citations


Journal ArticleDOI
TL;DR: In this article, a model for non-isothermal austenite formation in steels with initial microstructure consisting of ferrite and/or pearlite was developed, and a second model to describe the dilatometric behaviour of the steel and calculate the relative change in length which occurs during the formation has been developed.
Abstract: The main aim of this work is to study the mechanisms that control the austenitisation process in steels with different initial microstructures. The compiled knowledge in literature regarding the isothermal formation of austenite from different initial microstructures (pure and mixed microstructures), has been used in this work to develop a model for non-isothermal austenite formation in steels with initial microstructure consisting of ferrite and/or pearlite. The microstructural parameters that affect the nucleation and growth kinetics of austenite, and the influence of the heating rate have been considered in the modelling. Moreover, since dilatometric analysis is a technique very often employed to study phase transformations in steels, a second model to describe the dilatometric behaviour of the steel and calculate the relative change in length which occurs during the austenite formation has been developed. Both kinetics and dilatometric models have been validated. Experimental kinetic transformation, critical temperatures as well as the magnitude of the overall contraction due to austenite formation are in good agreement with calculations.

100 citations


Journal ArticleDOI
01 Oct 2001-Wear
TL;DR: In this paper, the sliding wear behavior of high-chromium white cast iron (16.8% Cr) has been examined as a function of silicon and Mischmetal alloy additions.

93 citations


Journal ArticleDOI
TL;DR: In this paper, the microstructure of fine interlocking acicular ferrite nucleated intragranularly at Ti2O3 inclusions was compared with those of coarser polygonal ferrite/pearlite and aligned ferrite with second phase.
Abstract: Low carbon–manganese wrought steels with three different microstructures were prepared by different thermomechanical treatments without changing the chemical composition and their mechanical properties were compared. The microstructure of fine interlocking acicular ferrite nucleated intragranularly at Ti2O3 inclusions shows higher strength and good toughness at low temperatures than those of coarser polygonal ferrite/pearlite and aligned ferrite with second phase.

81 citations


Journal ArticleDOI
TL;DR: In this article, an industrial forging procedure was developed to evaluate the influence of thermomechanical processing parameters on the microstructure and mechanical properties of V and V-Ti microalloyed steels.

81 citations


Journal ArticleDOI
TL;DR: In this article, a phenomenological kinetic model was developed for the description of diffusional austenite transformations in low-alloy hypoeutectoid steels during cooling after austenitization.

79 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of single and combined additions of vanadium and silicon on the mechanical properties of pearlitic steels being developed for wire rod production were investigated, and it was shown that the alloy additions are beneficial to the structural properties of the steels, especially the tensile strength.
Abstract: Systematic research has been undertaken on the effects of single and combined additions of vanadium and silicon on the mechanical properties of pearlitic steels being developed for wire rod production. Mechanical test results demonstrate that the alloy additions are beneficial to the mechanical properties of the steels, especially the tensile strength. Silicon strengthens pearlite mainly by solid-solution strengthening of the ferrite phase. Vanadium increases the strength of pearlite mainly by precipitation strengthening of the pearlitic ferrite. When added separately, these elements produce relatively greater strengthening at higher transformation temperatures. When added in combination the behavior is different, and substantial strength increments are produced at all transformation temperatures studied (550 °C to 650 °C). The addition of silicon and vanadium to very-high-carbon steels (>0.8 wt pct C) also suppresses the formation of a network of continuous grain-boundary cementite, so that these hypereutectoid materials have high strength coupled with adequate ductility for cold drawing. A wire-drawing trial showed that total drawing reductions in area of 90 pct could be obtained, leading to final tensile strengths of up to 2540 MPa in 3.3-mm-diameter wires.

74 citations


Journal ArticleDOI
TL;DR: In this paper, a static annealing of low-carbon steels severely deformed by equal-channel angular pressing was conducted, which resulted in the formation of cementite precipitations as well as the refinement of ferrite grains to submicrometer size.

Journal ArticleDOI
TL;DR: In this paper, a comparative study has been conducted on the microstructure, tensile, and axial fatigue behavior of two Fe•05Mo•15Cu• 175Ni alloys, made by binder-treated and diffusion alloying processes.
Abstract: A comparative study has been conducted on the microstructure, tensile, and axial fatigue behavior of two Fe‐05Mo‐15Cu‐ 175Ni alloys, made by binder-treated and diffusion alloying processes The mechanical properties will be explained in terms of the pore size and morphology, as well as the heterogeneous microstructures typical of ferrous powder metallurgy materials Binder treatment can provide a variety of advantages in manufacturing, over diffusion alloyed powders, including faster and more consistent flow into the die cavity, increased green strength, and reduction of fine particle dusting In addition to conventional porosity, smaller, ‘‘copper diffusion’’ pores were observed where copper particles had been prior to forming a liquid phase during sintering and diffusing into the Fe particles The microstructure in both alloys was typical of P:M alloy steels, with a heterogeneous microstructure consisting of areas of ‘‘divorced pearlite,’’ martensite, and nickel-rich ferrite The modulus and tensile strength of both types of alloys were equivalent Yield strength in the binder-treated alloy was higher which coincided with somewhat lower ductility The fatigue behavior in terms of stress versus cycles (S‐N curves) was almost identical for the two systems Fractographic observations showed fracture to have initiated primarily at pore clusters in the surface region Fracture surfaces after fatigue tests showed ductile fracture in the interparticle bridge regions, cleavage facets in pearlitic regions, and striations © 2001 Elsevier Science BV All rights reserved

Journal ArticleDOI
TL;DR: In this paper, a new physical significance of the bainite reaction in steels is proposed and analyzed, and it is found that the B petertoddS temperature can be defined by the point of intersection between the thermodynamic equilibrium curve for the austenite→ferrite transformation by coherent growth.
Abstract: The definition of the practical upper temperature limit of the bainite reaction in steels is discussed. Because the theoretical upper temperature limit of bainite reaction, B 0, can neither be obtained directly from experimental measurements, nor from calculations, then, different models related to the practical upper temperature limit of bainite reaction, B S, are reviewed and analyzed first in order to define the B 0 temperature. A new physical significance of the B S and B 0 temperatures in steels is proposed and analyzed. It is found that the B 0 temperature of the bainite reaction in steels can be defined by the point of intersection between the thermodynamic equilibrium curve for the austenite→ferrite transformation by coherent growth (curve Z $$\gamma \to \overrightarrow \alpha $$ ) and the extrapolated thermodynamic equilibrium curve for the austenite→cementite transformation (curve ES in the Fe-C phase diagram). The B S temperature for the bainite reaction is about 50–55 °C lower than the B 0 temperature in steels. Using this method, the B 0 and B S temperatures for plain carbon steels were found to be 680 °C and 630 °C, respectively. The bainite reaction can only be observed below 500 °C because it is obscured by the pearlite reaction which occurs prior to the bainite reaction in plain carbon steels. A new formula, B S(°C) =, 630-45Mn-40V-35Si-30Cr-25Mo-20Ni-15W, is proposed to predict the B S temperature of steel. The effect of steel composition on the B S temperature is discussed. It is shown that B S is mainly affected by alloying elements other than carbon, which had been found in previous investigations. The new formula gives a better agreement with experimental results than for 3 other empirical formulae when data from 82 low alloy steels from were examined. For more than 70% of these low alloy steels, the B S temperatures can be predicted by this new formula within ±25°C. It is believed that the new equation will have more extensive applicability than existing equations since it is based on data for a wide range of steel compositions (7 alloying elements).

Journal ArticleDOI
TL;DR: In this paper, a model that describes the pearlite-to-austenite transformation during continuous heating in a eutectoid steel has been developed, and the influence of structural parameters (such as the interlamellar spacing and edge length of pearlite colonies) and heating rate on the austenite formation kinetics has been experimentally studied and considered in the modeling.
Abstract: A model that describes the pearlite-to-austenite transformation during continuous heating in a eutectoid steel has been developed. The influence of structural parameters (such as the interlamellar spacing and edge length of pearlite colonies) and heating rate on the austenite formation kinetics has been experimentally studied and considered in the modeling. It has been found that the coarser the initial pearlite microstructure and the higher the heating rate, the slower the kinetics of austenite formation. Moreover, both the start and finish temperatures of the transformation slightly increase as the heating rate does, but the finish temperatures are more sensitive to that parameter. A good agreement (with an accuracy higher than 90 pct in the square correlation factor) between experimental and predicted values has been found.

Journal ArticleDOI
M. Hafiz1
TL;DR: In this paper, the correlation between tensile properties, impact toughness, hardness and pearlite content is investigated, and it is shown that the yield and ultimate tensile strengths are increased with increasing pearlite level in the matrix structure.
Abstract: Spheroidal graphite (SG) irons with a variety of matrix-structure have been produced. The correlation between tensile properties, impact toughness, hardness and pearlite content is investigated. The pearlite content is varied from 0 to about 95 per cent by the use of different heat treatment processes. The apparent variation in the properties with the pearlite level reveals the remarkable consistency in the relationships between mechanical properties and pearlite content. The study of the tensile properties showed that the yield and ultimate tensile strengths are increased with increasing pearlite level in the matrix structure. For matrix structure with 94.6% pearlite, the increases are about 91% and 98%, respectively, compared with those of the ferritic matrix material. The impact toughness of SG-iron is influenced significantly by matrix microstructure. Energy of about 230 × 103J/m2 is required to fracture a ferritic matrix SG-iron. On the other hand, when the matrix structure approaches a fully pearlitic matrix the fracture energy is decreased by an amount of 75.5%. The Brinell hardness value is found to increase with increasing pearlite content in the matrix structure of the present material. It increases from about 128 for a fully ferritic matrix to about 258 as the matrix structure approaches a fully pearlitic condition. This change in the hardness value reflects the change in the mechanical properties presented in this study.

Journal ArticleDOI
Yasuya Ohmori1
TL;DR: In this article, the orientation relationships between ferrite, carbide and austenite as well as the habit planes of plate-like transformation products and the mechanisms of transformations are discussed.
Abstract: The studies on the crystallographic features of diffusional transformation of austenite in various steels have been reviewed. A primary ferrite forming at an austenite grain boundary is related to at least one of the austenite grains separated by the boundary with the Bain correspondence. In the case of the microstructures containing both ferrite and carbides such as pearlite, degenerate pearlite, interphase precipitation of alloy carbides, and upper and lower bainites, the crystallographic relationships between ferrite and carbides provide further information to elucidate the transformation mechanisms. In the present report, therefore, the orientation relationships between ferrite, carbide and austenite as well as the habit planes of platelike transformation products and the mechanisms of transformations are discussed.

Journal ArticleDOI
01 Oct 2001-Wear
TL;DR: In this article, the abrasive wear resistance of ductile cast iron with different matrix microstructures (ferrite, pearlite, bainite and martensite) was studied under instrumented single-pass pendulum sclerometry testing.

Journal ArticleDOI
TL;DR: In this article, laser-ultrasonic measurements of longitudinal velocity in the 500-1000°C temperature range in carbon steel samples for different conditions known to affect phase transformations such as cooling rate, carbon concentration, and rolling were performed.
Abstract: This article presents accurate laser-ultrasonic measurements of longitudinal velocity in the 500–1000 °C temperature range in carbon steel samples for different conditions known to affect phase transformations such as cooling rate, carbon concentration, and rolling. Measurements were performed during continuous heating and cooling at rates varying between 0.1 and 20 °C/s. Carbon concentrations ranged from 0.0% to 0.72%. Hot-rolled and cold-rolled samples were measured. For the hot-rolled samples, a reproducible hysteresis was observed in the dependence of the ultrasonic velocity versus temperature of samples having a significant carbon concentration. This hysteresis is attributed to the combined effects of the phase transformation and of the ferromagnetic–paramagnetic transition. In particular, the rate of change of velocity with temperature during heating suddenly diminishes at the Curie temperature, and the velocity behavior during cooling shows clearly the start and end of phase transformations, even allowing discrimination between ferrite and pearlite nucleations. For the cold-rolled samples, significant drops in ultrasonic velocity were observed at the transformation temperatures when the samples were heated for the first time. However, the magnitude of these drops decreased for subsequent heating. These drops are attributed to irreversible crystallographic orientation changes caused by phase transformations. This effect was modeled using the Kurdjumov–Sach transformation relationship. The model calculation agrees well with the experimental data.

Patent
05 Apr 2001
TL;DR: In this paper, a method for manufacturing a high strength bolt excellent in the resistance to delayed fracture and to relaxation, characterized in that a steel product having a chemical composition, wherein C: 0.50 to 1.0 %, Si: 0., 0.5 % or less, Mn: 0, 2.2 to 1 %, P; 0.03% or less and S: 0%.
Abstract: A method for manufacturing a high strength bolt excellent in the resistance to delayed fracture and to relaxation, characterized in that a steel product having a chemical composition, wherein C: 0.50 to 1.0 % , Si: 0.5 % or less, Mn: 0.2 to 1 %, P; 0.03 % or less and S: 0.03 % or less, and having a structure, wherein the total area percentage of pro-eutectoid ferrite, pro-eutectoid cementite, bainite and martensite is 20 % or less and the balance is pearlite structure, is subjected to heavy wire drawing, the resulting wire is subjected to a cold heading to make a product having a bolt form, and the product is subjected to a blueing treatment in a temperature range of 100 to 400°C, thereby to manufacture a bolt form product having a tensile strength of 1200N/mm2 or higher and also being excellent in the resistance to delayed fracture and to relaxation.

Journal Article
TL;DR: The microstructure, tensile, and axial behavior of Fe-Mo-Cu-Ni alloys made by binder-treated processing were investigated and the attendant mechanical behavior compared to that of an anologous processed by diffusion alloying as discussed by the authors.
Abstract: The microstructure, tensile, and axial behavior of Fe-Mo-Cu-Ni alloys made by binder-treated processing were investigated and the attendant mechanical behavior compared to that of an anologous processed by diffusion alloying. Binder tretatment can provide a variety of advantages in manufacturing over diffusion alloyed powders, including faster and more consistent flow into the die cavity, increased green strenght, and reduction of fine particle dusting. In addition to conventional porosity, smaller, copper diffusion pores were observed where copper particles were present prior to forming a liquid phase during sintering and diffusion into the iron particles. The heterogenous microstructure in both alloys was typical of P/M alloy steels, consisting of areas of divorced pearlite, martensite, and nickel-rich ferrite. Tensile and fatigue resistance were enhanced by an increase in the molybdenum content in the alloys. The tensile strenght of both types of alloys was similar and fatigue life was essentially identical for the two systems. Fractographic observations showed that fracture initiated primarly at pore clusters in the surface region. Investigation of small cracks by a surface replication technique showed that fatigue cracks by a surface replication technique showed that fatigue cracks nucleated at pores or pore clusters, and that crack propagation exhibited a significant amount of deflextion and branching, attributed to local obstacles in the interparticle bridge regions, cleavage facets in pearlitic regions, and striations due to cyclic loding.

Patent
Hong-Chul Jeong1, Hae-Chang Choi1
16 Nov 2001
TL;DR: A welding structural steel product exhibiting a superior heat affected zone toughness, comprising, in terms of percent by weight, 0.03 to 0.17% C,0.4 to 2.0%, 0.005 and 0.2% W, at most 0.3 to 0.03% P, at more than 0.004% S, and balance Fe and incidental impurities while satisfying conditions of 1.2≦Ti/N≦2.5, 10≦N/B≦40, 2.5≦Al/N/N
Abstract: A welding structural steel product exhibiting a superior heat affected zone toughness, comprising, in terms of percent by weight, 0.03 to 0.17% C, 0.01 to 0.5% Si, 0.4 to 2.0% Mn, 0.005 to 0.2% Ti, 0.0005 to 0.1% Al, 0.008 to 0.030% N, 0.0003 to 0.01% 0.00 1 to 0.2% W, at most 0.03% P, at most 0.03% S, at most 0.005% 0, and balance Fe and incidental impurities while satisfying conditions of 1.2≦Ti/N≦2.5, 10≦N/B≦40, 2.5≦Al/N≦7, and 6.5≦(Ti+2Al+4B)/N≦14, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 μm or less. The method includes the steps of preparing a slab of the above-described composition, heating the slab to 1,100° C. to 1,250° C. for 60-180 minutes, hot rolling the heated slab in an austenite recrystallization range at a 40% or more rolling reduction followed by controlled cooling.

Journal ArticleDOI
TL;DR: In this article, the effect of vanadium on the thermal stability of ultrafine-grained (UFG) low-carbon steel fabricated by intense plastic straining was examined, and the microstructural evolution during annealing and the tensile properties of the two steels were compared.
Abstract: Two grades of low-carbon steel, one containing vanadium and the other without vanadium, were subjected to equal channel angular pressing (ECAP) at 623 K up to an effective strain of ∼4. After equal channel angular pressing, a static annealing treatment for 1 hour was undertaken on both pressed steels in the temperature range of 693 to 873 K. By comparing the microstructural evolution during annealing and the tensile properties of the two steels, the effect of the addition of vanadium on the thermal stability of ultrafine-grained (UFG) low-carbon steel fabricated by intense plastic straining was examined. For the steel without vanadium, coarse recrystallized ferrite grains appeared at annealing temperatures above 753 K, and a resultant degradation of the strength was observed. For the steel containing vanadium, submicrometer-order ferrite grain size and ultrahigh strength were preserved up to 813 K. The enhanced thermal and mechanical stabilities of the steel containing vanadium were attributed to its peculiar microstructure, which consisted of ill-defined pearlite colonies and ultrafine ferrite grains with uniformly distributed nanometer-sized cementite particles. This microstructure resulted from the combined effects of (a) the preservation of high dislocation density providing an effective diffusion path, due to the effect of vanadium on increasing the recrystallization temperature of the steel; and (b) precipitation of fine cementite particles at ferrite grain boundaries through the enhanced diffusion of carbon atoms (which were dissolved from pearlitic cementite by severe plastic straining) along ferrite grain boundaries and dislocation cores.

Journal ArticleDOI
TL;DR: In this paper, an attempt has been made to establish a relationship between hardness and tensile properties for various single structured steels: ferrite, pearlite, bainite, and martensite.
Abstract: An attempt has been made to establish a relationship between hardness and tensile properties for various single structured steels: ferrite, pearlite, bainite, and martensite. It is found that the proportionality constant A Y of hardness to yield strength changes from 5.79 to 3.17 and is highest for the ferrite steel and lowest for the tempered martensitic steels. A less pronounced change was found in the proportionality constant A T of hardness to tensile strength (from 3.97 to 2.72). A dependence on microstructure of the proportionality constant at 8% strain A 0.08 was found as well. This difference in A was found to be attributable mostly to the effect of different work hardening behaviours owing to different microstructures. Regression analysis shows that hardness can be expressed as a function of accessible material parameters such as composition, grain size, and transformation temperatures for various single structured steels within a certain degree of accuracy.

Journal ArticleDOI
TL;DR: In this article, the authors describe the characteristics and kinetics of graphitization, reviews pertinent laboratory and field experience, and summarizes time-temperature service regimes within which graphitisation can be anticipated.
Abstract: Prolonged exposure of carbon and low alloy steel components to temperatures exceeding 800 °F (427 °C) can result in several kinds of material microstructural deterioration; for example, creep cavitation, carbide coarsening and/or spheroidization, and, less commonly, graphitization. Graphitization generally results from the decomposition of pearlite (iron + iron carbide) into the equilibrium structure of iron + graphite and can severely embrittle the steel when the graphite particles or nodules form in a planar, continuous manner. Graphitization has resulted in the premature failure of pressure boundary components, including high energy piping and boiler tubes. Failure due to graphitization continues to be of concern in long-term aged carbon and carbon-molybdenum steels, both in weldments and in base metal, where, as recently reported, prior deformation or cold work could accelerate the graphitization process. This paper describes the characteristics and kinetics of graphitization, reviews pertinent laboratory and field experience, and summarizes time-temperature service regimes within which graphitization can be anticipated.

Patent
14 Dec 2001
TL;DR: In this article, the authors have disclosed that carbon steels of high performance contain dislocated lath structures in which laths of martensite alternate with thin films of austenite.
Abstract: Carbon steels of high performance are disclosed that contain dislocated lath structures in which laths of martensite alternate with thin films of austenite, but in which each grain of the dislocated lath structure is limited to a single microstructure variant by orienting all austenite thin films in the same direction. This is achieved by careful control of the grain size to less than ten microns. Further improvement in the performance of the steel is achieved by processing the steel in such a way that the formation of bainite, pearlite, and interphase precipitation is avoided.

Journal ArticleDOI
TL;DR: In this article, a theoretical model is presented to calculate the evolution of austenite-to-allotriomorphic ferrite transformation with time at a very wide temperature range.
Abstract: The present article is concerned with the theoretical and experimental study of the growth kinetics of allotriomorphic ferrite in medium carbon vanadium-titanium microalloyed steel. A theoretical model is presented in this work to calculate the evolution of austenite-to-allotriomorphic ferrite transformation with time at a very wide temperature range. At temperatures above eutectoid temperature, where allotriomorphic ferrite is the only austenite transformation product, the soft-impingement effect should be taken into account in the modeling. In that case, the Gilmour et al. analysis reliably predicts the progress of austenite-to-allotriomorphic ferrite transformation in this steel. By contrast, since pearlite acts as a carbon sink, the carbon enrichment of austenite due to the previous ferrite formation is avoided, and carbon concentration in austenite far from the α/γ interface remains the same as the overall carbon content of the steel. Hence, the soft-impingement effect should be neglected, and allotriomorphic ferrite is considered to grow under a parabolic law. Therefore, assumption of a semi-infinite extent austenite with constant boundary conditions is suitable for the kinetics of the isothermal decomposition of austenite. An excellent agreement (higher than 93 pct in R2) has been obtained between the experimental and predicted values of the volume fraction of ferrite in all of the ranges of temperature studied.

Journal ArticleDOI
TL;DR: In this paper, the processes of bainitic structure formation in Fe-9%Ni-C alloys have been investigated by means of transmission electron and hot stage optical microscopies.

Journal ArticleDOI
TL;DR: In this paper, a microstructure-based modeling of the environmentally assisted fracture phenomenon is proposed to rationalize the results for diferent degrees of drawing, based on the model by Miller and Smith of shear cracking in pearlite.
Abstract: This paper analyzes the process of hydrogen assisted cracking in pearlitic steels, which are increasingly cold drawn in the course of manufacturing to produce prestressing steel wires used in prestressed concrete. A microstructure-based modeling of the environmentally-assisted fracture phenomenon is proposed to rationalize the results for diferent degrees of drawing. The approach is based on two items — (i) the model by Miller and Smith of shear cracking (SC) in pearlite; (ii) the mechanism of hydrogen enhanced decohesion (HEDE) proposed by Gerberich. There is an evolution from a predominant micromechanism of SC in slightly drawn steels to a predominant micromechanism of HEDE in heavily drawn steels.

Patent
13 Aug 2001
TL;DR: In this article, a bearing device is provided with a bearing ring and a shaft body that is made of carbon steel including pearlite having a cementite layer structure, and has an end portion caulked onto the bearing ring, at least in the end portion of the shaft body, the layer gap of the cementite in the pearlite is made greater.
Abstract: A bearing device is provided with a bearing ring and a shaft body that is made of carbon steel including pearlite having a cementite layer structure, and has an end portion caulked onto the bearing ring, and in this device, at least in the end portion of the shaft body, the layer gap of the cementite in the pearlite is made greater.

Journal ArticleDOI
Dong-Woo Suh1, Jin Ho Bae1, Jae-Young Cho1, Kyu Hwan Oh1, Hu-Chul Lee1 
TL;DR: In this article, the authors used finite element method (FEM) with regression equations for flow curves of each ferrite and pearlite phase proposed by Hiramatsu et al. and Furukawa et al., which showed that the calculated flow strength of ferrite/pearlite two-phase steel was lower than the experimentally measured one.
Abstract: Flow curves of ferrite/pearlite two-phase steels were simulated using finite element method (FEM) with regression equations for flow curves of each ferrite and pearlite phase proposed by Hiramatsu et al. and Furukawa et al. The calculated flow strength of ferrite/pearlite two-phase steel was lower than the experimentally measured one mainly due to the underestimation of flow strength of ferrite phase according to the yield elongation. To improve the simulation, the flow curves in homogeneous deformation range were considered. Microscopic observations revealed that most deformation was accumulated in the ferrite phase during yield elongation. Flow curves of ferrite phase were re-evaluated based on this observation and flow curves of ferrite/pearlite steels were also re-calculated. Re-calculated yield strength of ferrite/pearlite steels showed good agreement with measured ones, however the work hardening rate of re-calculated flow curves is still lower than that of measured one. The simplicity of pearlite morphology for FEM analysis is thought to be responsible for lower work hardening behavior of calculated flow curve by FEM than that of measured one.