Microstructural evolution of AISI304 stainless steel in the Steckel Mill rolling process

Includes bibliographical references (leaves [105]-110).The microstructural evolution of AISI304 stainless steel in the Steckel mill rolling process is investigated. This study includes the analysis of mill logs, microstructural examination of the mill product, deformation simulations and post deformation heat treatments. The mill logs from industry contains information about various process variables such as temperature, roll speed, dimensions of the mill strip and forces applied to it during the hot mill rolling process. The strain, strain rates and stresses on the mill strip can be calculated from the mill logs. An understanding of the metallurgical changes during rolling process can be gained by analysing the mean flow stress trends that evolve during rolling. Microstructural examination of the strip in different regions allows us to evaluate the property variations in the strip. This was done with microhardness testing, conventional optical microscopy and electron backscatter diffraction. The middle section of the strip demonstrated full recrystallization whereas the head and tail sections demonstrated no signs of recrystallization. The property differences through thickness proved to be negligible. Laboratory simulation was done in uniaxial compression testing on a Cam Plastometer. It was found that the temperature has a profound influence on the flow stress and the microstructure. The strain rates experienced in hot rolling does not have a significant effect on the flow stress and no measurable effect on the hardness. Heat treatments were done on the deformed uniaxial compression samples. The results of these heat treatments were analysed by two different methods: to deform the sample again after the heat treatment and to compare the yield stress from the first and second deformation and to measure the changes in room temperature hardness with the heat treatment time. The latter led to the development of a time to 50% recrystallization equation that allows the prediction of a direct annealing time for complete softening at the conclusion of the hot rolling process

Optimisation and Characterisation of a Curved Bimetallic Blade and its Performance Within a Thermal Motor

In most flat bimetallic strip applications, the bending is employed in the transverse direction, that is, upon the application of uniform heating to the entire strip, the initially straight strip bends transversely up from the flat plane. This study is concerned with a pre-curved bimetallic strip that upon heating up from the ambient, straightens up along the chord line tending to become flatter. The initial ambient radius of curvature of the strip is smaller, and upon heating, the radius of curvature becomes larger. By mounting the curved bimetallic strip with a rotational degree of freedom at each end, and fixing one end against displacement, a chord line displacement of the free end of the strip occurs when the strip is uniformly heated. It is this chord line case that this work investigates and characterises. This work provides a way of evaluating the net combined axial loading case whereby an external load is applied to the free end of the strip as it uniformly heated. The main application of this work is for the characterisation of a curved bimetallic blade within a thermal motor. This is a novel device for converting renewable heat energy into mechanical energy and power as part of a larger energy harvesting network. The curved bimetallic strip with minor modifications, functions as a curved bimetallic blade within the thermal motor. The application of this work has a wider impact, in that it can be used in any other temperature induced force and displacement applications. Thus as a result of this investigation, a new form of linear actuator has been created that can utilise an input heat differential, and produce an output axial force and displacement. The displacements and forces generated by the axial case can be quite large, and as a result of this work, relatively easy to calculate, when designing a thermally driven linear actuator. The thermal motor, which possesses the curved bimetallic strip at the heart of its mechanism, can also be powered by other secondary heating sources such exhaust, or waste heat, that would otherwise be lost to the surroundings

Beyond energy efficiency : actors, networks and government intervention in the development of industrial process technologies

Het proefschrift geeft vier gedetailleerde verhalen over de ontwikkelingsgeschiedenis van industriële procestechnologieën voor de papierindustrie en de staalindustrie: de schoenpers, impulstechnologie, strip-casting technologie en smeltreductie technologie. Deze 4 technologieën staan bekend als doorbraaktechnologieën die het energieverbruik per ton papier of staal beloven te verminderen. De overheid is geïnteresseerd in de ontwikkeling van dit soort technologieën omdat ze op de lange termijn het energieverbruik per ton kunnen reduceren (zodat ook in de toekomst de CO2-emissies van de zware industrie verder om laag kunnen). De vier ontwikkelingsgeschiedenissen worden vergeleken om af te sluiten met suggesties voor de overheid om de ontwikkeling van industriële procestechnologieën te stimuleren. Het proefschrift laat zien dat sturing van energie-efficiënte procestechnologieën lastig is voor de overheid. Technologieontwikkeling voor de zware industrie gaat traag en de stappen die genomen worden zijn klein. Het bouwt sterk voort op het bestaande productieproces. Wanneer de stap van een innovatieve technologie ten opzichte van het bestaande proces te groot is begint men er simpelweg niet aan. Aan de andere kant moet de verbetering van de kosten per ton product wel groot genoeg zijn om de langdurige en dure ontwikkelingtrajecten te verantwoorden. De verbeteringen in energie-efficiëntie liften mee op de ontwikkeling; de procestechnologieën worden ontwikkeld omdat ze de productiecapaciteit van het bestaande proces vergroten of de productkwaliteit verbeteren. Ook al is stimuleren lastig, het is niet onmogelijk. Voor effectieve stimulering is beleid op maat nodig. Het veld van doorbraaktechnologieën voor de industrie is te divers om generiek beleid te voeren. De kans op free-riders is te groot. De overheid moet geïnformeerd zijn over het vertrouwen dat de industrie heeft in een nieuwe procestechnologie. Wanneer het vertrouwen erg laag is of juist erg hoog, dan heeft interventie geen additioneel effect. Overheidsinterventie zou meer succes hebben wanneer de overheid op de hoogte is van de netwerken, de kennis en ervaring van betrokken actoren die de technologie ontwikkelen. Daarnaast moet een overheid oog hebben voor wat de innovatieve technologie met het produktieproces doet. Stimuleren van technologieontwikkeling begint dus niet alleen bij kennis over de doorbraaktechnologie - en dan niet alleen investeringskosten en energiebesparingskosten, maar ook andere voordelen en inpassingskenmerken -, maar juist ook bij kennis over (internationaal actieve) actoren. Inzicht in het internationale technologienetwerk vergroot de kans op succesvolle overheidsinterventie

National Educators' Workshop: Update 1991. Standard Experiments in Engineering Materials Science and Technology

Given here is a collection of experiments presented and demonstrated at the National Educators' Workshop: Update 91, held at the Oak Ridge National Laboratory on November 12-14, 1991. The experiments related to the nature and properties of engineering materials and provided information to assist in teaching about materials in the education community

Energy Efficiency Improvement and Cost Saving Opportunities for the U.S. Iron and Steel Industry An ENERGY STAR(R) Guide for Energy and Plant Managers

Energy is an important cost factor in the U.S iron and steel industry. Energy efficiency improvement is an important way to reduce these costs and to increase predictable earnings, especially in times of high energy price volatility. There are a variety of opportunities available at individual plants in the U.S. iron and steel industry to reduce energy consumption in a cost-effective manner. This Energy Guide discusses energy efficiency practices and energy-efficient technologies that can be implemented at the component, process, facility, and organizational levels. A discussion of the structure, production trends, energy consumption, and greenhouse gas emissions of the iron and steel industry is provided along with a description of the major process technologies used within the industry. Next, a wide variety of energy efficiency measures are described. Many measure descriptions include expected savings in energy and energy-related costs, based on case study data from real-world applications in the steel and related industries worldwide. Typical measure payback periods and references to further information in the technical literature are also provided, when available. The information in this Energy Guide is intended to help energy and plant managers in the U.S. iron and steel industry reduce energy consumption and greenhouse gas emissions in a cost-effective manner while maintaining the quality of products manufactured. Further research on the economics of all measures?and on their applicability to different production practices?is needed to assess their cost effectiveness at individual plants

Laser Cladding for use in Extreme Tribological Interfaces

Coatings are common in engineering applications for protecting the surface of components, either from exposure to environmental conditions or from contact with other components. Laser cladding is a coating technique which allows for thicker coatings of various alloys that enable high load bearing interfaces to operate at a wider range of loads or for longer, for example by increasing durability. This is of great benefit to the railways industry as well as other heavy industries, such as the steel industry. Laser clad coatings have been used extensively in other industries such as oil and gas for increasing the durability of drilling components; in mining and earth moving equipment, for increasing the durability of the components that come in contact with hard soil and rocks. Both are extreme interfaces. In this study, new interfaces and extreme conditions for new industries are investigated, by highlighting the laser clad coating advantages, when used under extreme conditions. The extreme test conditions have not been investigated in published literature, especially with the use of laser clad coatings. This project evaluated the performance of laser cladding coatings on railway components such as the wheel and rail. Other interfaces found in machinery in the steel industry were considered, specifically in the rolling of steel. A variety of interfaces were evaluated by modelling and testing, such as rolling-sliding, high pressure water jet erosion and impact. Three clad materials were identified as suitable for the chosen interfaces, martensitic stainless steel (MSS), Stellite 6 (Co-Cr) and a two-layer clad of Inconel 625 with Technolase. The clad parameters were fixed, resulting in constant material grades, allowing the coatings used in different interfaces to be comparable. The materials choice was based on published research on similar interfaces. Tests were performed on existing test rigs for rolling-sliding and bending tests. The impact test was performed on a rig modified specifically for this study, while a bespoke rig was built for the erosion test. Metallographic techniques were used for all materials, to prepare the samples for characterisation using optical and electron microscopy, as well as nanoindentation and microhardness. Pre- and post-test material analysis was performed. The use of computer modelling was considered mainly for the generation of test parameters, while the results from testing were compared to existing data. Key findings highlight that the use of the selected clad materials under the chosen extreme interfaces can have a positive effect on the durability of the coating, mainly by increasing the wear resistance properties of the coating. Furthermore, the two-layer clad coating showed promising results in stopping crack propagation to the substrate. The test results can be used in predictive tools by researchers in academia, as well as in industry, as a way of introducing laser cladding applications to interfaces of engineering products. Furthermore, the performance of the chosen materials indicates that this study may be used as the basis for selecting similar clad coatings for pilot trials or large scale testing

Advances in Low-carbon and Stainless Steels

This Special Issue of Metals was dedicated to recent advances in low-carbon and stainless steels. Although these types of steels are not new, they are still receiving considerable attention from both research and industry sectors due to their wide range of applications and their complex microstructure and behavior under different conditions. The microstructure of low-carbon and stainless steels resulting from solidification, phase transformation, and hot working is complex, which, in turn, affect their performance under different working conditions. A detailed understanding of the microstructure, properties, and performance for these steels has been the aim of steel scientists for a long time. This Issue received quality papers on different aspects of these steels including their solidification, thermomechanical processing, phase transformation, texture, etc., and their mechanical and corrosion behaviors

Modelling and experimental study of the spray forming of dissimilar metals

This research describes a systematic study to develop a strong interfacial bond in as-sprayed dissimilar metallic alloys. Non-destructive three-dimensional microstructure and residual stress characterisations via X-ray micro-computed tomography and neutron diffraction, respectively and numerical modelling of the preform shape evolution, transient heat flow and thermal residual stress developed were employed. The study revealed quantitatively the links between the key spray forming parameters, corresponding microstructures formed and the interfacial bonding characteristics in thick as-sprayed dissimilar metallic alloys.The key novelties of this research include:- The development of a preform shape and heat flow model that incorporates: (1) the use of a mesh deformation method with automated re-meshing algorithm to model the growing preforms and address the coupling of droplet mass/enthalpy input at the deposition surface and (2) a substrate induction preheating model.- Validated against experimental measurements, the preform heat flow model was used to establish the correlations between the preform thermal history and microstructures formed. The correlations established based on the tomography and diffraction measurements showed their interrelationship and agreements with one another. The correlations also provided the crucial links to take into account the effects of the microstructure formed on the corresponding material properties and stresses developed in the preform after cooling.- The combined use of thermal residual stress modelling and neutron diffraction in this research presents, for the first time, the nondestructive quantitative assessment of the interfacial bonding in thick as-sprayed dissimilar steels preforms. The effects of different substrate and spray temperatures on the microstructures, residual stress and interfacial bond developed were investigated systematically.- The dynamics of the atomised droplets rapid microstructural change during deposition were revealed when subjected to rapid Joule heating (~500 K s-1) to a range of isothermal temperatures in the vicinity of the precipitate solvus and alloy solidus temperatures with a short (~10 s) high temperature holding time. A finite element model of the transient heat flow in the powder compact was developed to provide more quantitative information of the specimen internal temperature distribution which was otherwise unavailable and the rapid microstructural change in the powders was rationalised in terms of the transient temperature conditions. These results can be useful in reconciling thermal histories and microstructures in the as-sprayed preforms, and may guide the optimisation of the spray forming process if desirable microstructural features are to be preserved into the bulk preform.- The elastic and plastic deformation behaviours of the spray formed steels containing different levels of porosity and the integrity of the bonded interface of the spray formed dissimilar steels were studied in situ via three-point bend tests with neutron diffraction. The study revealed the role of the constituent phases in the as-sprayed high speed steel when subjected to stresses above the elastic limit and the characteristics of the interfacial bond formed in comparison to the non-destructive assessment carried out in this research

Fast algorithms for material specific process chain design and analysis in metal forming - final report DFG Priority Programme SPP 1204

The book summarises the results of the DFG-funded coordinated priority programme \"Fast Algorithms for Material Specific Process Chain Design and Analysis in Metal Forming\". In the first part it includes articles which provide a general introduction and overview on the field of process modeling in metal forming. The second part collates the reports from all projects included in the priority programme

Best Available Techniques (BAT) Reference Document:for:Iron and Steel Production:Industrial Emissions Directive 2010/75/EU:(Integrated Pollution Prevention and Control)

The BREF entitled ‘Iron and Steel Production’ forms part of a series presenting the results of an exchange of information between EU Member States, the industries concerned, non-governmental organisations promoting environmental protection and the Commission, to draw up, review, and where necessary, update BAT reference documents as required by Article 13(1) of the Directive. This document is published by the European Commission pursuant to Article 13(6) of the Directive. This BREF for the iron and steel production industry covers the following specified in Annex I to Directive 2010/75/EU, namely: • activity 1.3: coke production • activity 2.1: metal ore (including sulphide ore) roasting and sintering • activity 2.2: production of pig iron or steel (primary or secondary fusion) including continuous casting, with a capacity exceeding 2.5 tonnes per hour. The document also covers some activities that may be directly associated to these activities on the same site. Important issues for the implementation of Directive 2010/75/EU in the production of iron and steel are the reduction of emissions to air; efficient energy and raw material usage; minimisation, recovery and the recycling of process residues; as well as effective environmental and energy management systems. The BREF document contains 13 chapters. Chapter 1 provides general information on the iron and steel sector. Chapter 2 provides information and data on general industrial processes used within this sector. Chapters 3 to 8 provide information on particular iron and steel processes (sinter plants, pelletisation, coke ovens, blast furnaces, basic oxygen steelmaking and casting, electric arc steelmaking and casting). In Chapter 9 the BAT conclusions, as defined in Article 3(12) of the Directive, are presented for the sectors described in Chapters 2 to 8.JRC.J.5-Sustainable Production and Consumptio