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Identification of the critical process conditions that enhance Cu diffusion in ferrite grain boundaries and promote precipitation of Cu-rich particles in the proximity of steel semi-finished products surface is crucial for every steel maker as it leads to the creation of hot shortness cracks in final products deteriorating surface condition. The purpose of this paper is to reveal the possible effect of Cu segregation in the metal/oxide interface, its role in surface crack initiation and, finally, to propose actions to prevent from hot shortness issues throughout the production chain of steel products.

The here presented study was based on S355 steel plate production starting from re-melting of scrap in an EAF, followed by metallurgical treatment in a Ladle Furnace, continuous casting, re-heating (RH) and thermo-mechanical rolling in a reversing mill. For the purposes of this study, more than ten heats, 100 t of steel each, were analyzed. Here presented are depicted steels in the high and low end of the permitted Cu-wt-% spectrum, 0.4 wt-% Cu (0.15 wt-% C, 1.1 wt-% Mn, VTi micro-alloyed steel) and 0.25 wt-% Cu (0.09 wt-% C, 1.2 wt-% Mn, NbTi micro alloyed steel), respectively.

Although Cu levels of 0.25-0.40 wt-% are well below the Cu solubility in austenite and ferrite (8 percent wt-% and 3 wt-% Cu, respectively) and within specifications, precipitation of Cu-rich particles is observed in industrial semi-finished and/or final products. Cu-rich precipitates and Cu segregation along grain boundaries near the steel surface lead to hot shortness cracks in industrial products.

Hot shortness surface defects related to Cu presence in steel having significantly lower Cu amounts than its maximum solubility in austenite and ferrite does not make sense in first place. Correctly, Cu is expected to remain in solid solution. Identification of Cu-rich particles is explained on the basis of the development of double diffusion actions: interstitial diffusion of carbon (decarburization) and substitution diffusion of copper. Root cause analysis and reliable countermeasures will save financial and material resources during steel production.

Automobile scrap re-melting results in noticeable Cu amounts in EAF produced steel. Presence of Cu-rich particles in grain boundaries near the surface of intermediate or final products deteriorates surface quality through relevant surface defects. Identification of Cu-rich particles is explained on the basis of the development of double diffusion actions: interstitial diffusion of carbon and substitution diffusion of copper. Pre condition for metallic Cu precipitation in ferrite is the Cu amount to be above 3 wt-%, which is ten times higher than the usual permitted Cu amount in such steel grades. This pre-condition is met through austenite oxidation during RH.

The reported mathematical models of gas–liquid flow in single snorkel Rheinstahl–Heraeus (SSRH) are based on the assumption of steady Ar-molten steel flow. The purpose of this paper is to develop a mathematical model to describe the unsteady turbulent flow (CO-Ar-molten steel) with nonequilibrium decarburization reaction.

On the base of the finite volume method, the computational fluid dynamics software CFX is used to predict the unsteady fluid flow, the spatial distributions of CO/argon gas and carbon element. The water model experiment and the industrial experiment are carried out to verify the mathematical models.

A two-way coupling model (T-WCM) based on algebraic slip model is developed to investigate the coupling phenomena. The related results show that T-WCM is more rigorous and accurate than one-way coupling model in predicting carbon content of molten steel. The amount of CO gas, which can enhance turbulent flow and mass transfer, is about three times the argon gas blown into SSRH.

CO gas is the key factor in investigating the transport phenomena. This study fully reveals the truth about the unsteady gas-liquid flow in SSRH. It is necessary to adopt T-WCM based on algebraic slip model to describe the CO-Ar-molten steel flow phenomenon.

The purpose of this paper is to investigate the fatigue and failure of commercial vehicle serial stress-peened leaf springs, emphasizing the technological impact of the material, the thermal treatment and the stress-peening process on the microstructure, the mechanical properties and the fatigue life. Theoretical fatigue analysis determines the influence of each individual technological parameter. Design engineers can assess the effectiveness of each manufacturing process step qualitatively and quantitatively, and derive conclusions regarding its improvement in terms of mechanical properties and fatigue life.

Two different batches of 51CrV4 were examined to account for potential batch influences. Both specimen batches were subjected to the same heat treatment and stress-peening process. Investigations of their microstructure, hardness and residual stress state on the surface’ areas show the effect of the manufacturing process on the mechanical properties. Wöhler curves have been experimentally determined for the design of high-performance leaf springs. Theoretical fatigue analyses reveal the influence of every above mentioned technological factor on the fatigue life of the specimens. Therewith, the effectiveness and potential for further improvement of the manufacturing process steps are assessed.

Microstructural analysis and hardness measurements quantify the decarburization and the degradation of the specimens’ surface properties. The stress-peening process causes significant compressive residual stresses which improve the fatigue life. On the other hand, it also leads to pronounced surface roughness, which reduces the fatigue life. The theoretical fatigue life analysis assesses the mutual effect of these two parameters. Both parameters cancel each other out in regards to the final effect on fatigue life. The sensitivity of the material and the potential for further improvement of both heat treatment and stress peening is appointed.

All quantitative values given here are strictly valid for the present leaf spring batches and should not be widely applied. The results of the present study indicate the sensitivity of high-strength spring steel used here to the various technological factors resulting from the heat treatment and the stress-peening process. In addition, it can be concluded that further research is necessary to improve the two processes (heat treatment process and the stress peening) under serial production conditions.

The microstructure investigations in conjunction with the hardness measurements reveal the significant decrease of the mechanical properties of the highly stressed (failure-critical) tensile surface. Therewith, the potential for improvement of the heat treatment process, e.g. in more neutral and controlled atmosphere, can be derived. In addition, significant potential for improvement of the serially applied stress-peening process is revealed.

The paper shows a systematic procedure to assess every individual manufacturing factor affecting the microstructure, the surface properties and finally, the fatigue life of leaf springs. An essential result is the quantification of the surface decarburization and its influence on the mechanical properties. The methodology proposed and applied within the theoretical fatigue life analysis to quantify the effect of technological factors on the fatigue life of leaf springs can be extended to any engineering component made of high-strength steel.

IT has recently been said by a member of a firm of justly‐famous wire makers (1) that there is probably no finer grade of wire than that designed for aero‐engine valve springs to Air Ministry Specification D.T.D.5A, and despite the fact that this article will deal principally with defects in that wire, the author, from an experience gained from the handling of some hundreds of miles of it, must state at the outset that he can endorse this opinion.

Coatings Solve Descaling Problems. Formidable problems of oxidation and scale formation are encountered in the heat treatment of creep‐resistant and heat‐resistant metals which demand lengthy descaling operations after treatment, or the use of controlled‐atmosphere or vacuum furnaces. Within the last two years, however, Rolls‐Royce Ltd. have developed protective coatings which, as a result of subsequent co‐operation with F. W. Berk & Co. Ltd., are available under the name of Berkatekt for protecting the metals from oxidation, intergranular corrosion and decarburisation during treatment.

The aluminide and CeO₂ and La₂O₃ containing aluminide coatings on carbon steel have been prepared by a pack cementation process. The influence of CeO₂ and La₂O₃ additions on the oxidation rates of aluminide coatings has been investigated. The performance of coatings was studied by measuring oxidation kinetics, metallography, SEM and X‐ray diffraction analysis techniques. The oxidation‐resistance of coated carbon steel is discussed on the basis of a decrease in oxidation rates as well as adherence of oxide scales. The oxidation rates of carbon steel and aluminide coatings were markedly reduced in the presence of CeO₂ and La₂O₃ in the temperature range of 700‐900°C. The oxidation rates were significantly affected by the morphology of oxide scales. In the case where the structure of oxides scales was not seriously disrupted due to decarburisation, the oxidation rates were significantly reduced.

The purpose of this study is to prepare WC-10Co-4Cr coatings using two processes of plasma spraying and high-velocity oxygen fuel (HVOF) spraying. The decarburization behaviors of the different processes are analyzed individually. The microstructural characteristics of the as-sprayed coatings are presented and the wear mechanisms of the different WC–10Co–4Cr coatings are discussed in detail.

The WC–10Co–4Cr coatings were formed on the surface of Q235 steel by plasma and HVOF spraying.

Plasma spraying causes more decarburizing decomposition of the WC phase than HVOF spraying. In the plasma spraying process, η(Cr25Co25W8C2) phase appears and the C content decreases from the top surface of the coating to the substrate.

In this study, two WC–10Co–4Cr coatings on Q235 steel prepared by plasma and HVOF spraying were compared with respect to the sliding wear behavior.

The wear mechanisms of the plasma- and HVOF-sprayed coatings were abrasive and oxidation, respectively.

Nickel aluminide coatings on mild steel have been prepared by pack cementation process. The high temperature oxidation behaviour of the coatings have been studied at 750°, 800° and 850° in flowing air. The influence of different rare earth oxide addition on the oxidation rates of nickel aluminide coating on mild steel has also been investigated. The kinetic of the oxidation of nickel aluminide coating on mild steel, with or without addition of RE2O3 proceeds by a diffusion controlled mechanism as revealed by the parabolic nature of weight gain Vs time plots. At higher temperatures the oxidation rates of the nickel aluminide coatings are lowered down markedly irrespective of rare earth oxide concentration. The oxidation rates are significantly affected by the morphology of the oxide scales, in cases where the structure of oxide scales is not seriously disrupted due to decarburization, the oxidation rates are significantly reduced.

TO make alloy steel we draw almost entirely upon material from outside the United States. We produce our own molybdenum. Our nickel comes from Canada and so does a part of our copper. Manganese and chromium are nearly all imported. We produce some tungsten and substantial amounts of vanadium. Tin, columbium and other vital materials are imported.

Discusses the distress of mine rope‐wires, under the diverse states of stresses and strains of physical, chemical and mechanical origin. Mine rope‐wires undergo complicated cycles of stresses and strains inside the depth of coal and metal mines. This assumes special significance during summer inside the deeper mines. Summarizes recent studies in this field and compares their results.