Steel Makers Research Articles

Installation, Startup, and Performance of a Static VAR Compensator for an Electric Arc Furnace Upgrade

This steel maker upgraded the electric arc furnace (EAF) melt shop to increase production and improve the metallurgical quality of their product. The increased electrical load and harmonic generation for the new 50 MVA furnace operation necessitated the installation of an 80 MVAR static VAR compensator (SVC) to meet utility interconnect requirements. This paper is a follow-up and companion to the author's previous paper that documented comprehensive analysis to specify the SVC. This paper describes the sequence of events during the installation, commissioning, and operation of the SVC. It will assess the performance of the SVC compared with the electrical requirements of the utility for voltage regulation, flicker, harmonics, and power factor. Power quality measurements during EAF operation without the SVC established a baseline to compare improvements provided by the SVC as well as compliance with the utility limits. Additionally, events encountered during the commissioning are shared as lessons learned.

Sustainable steel production – Swedish initiative to ‘close the loop’

ABSTRACTEnvironmental considerations of steel manufacturing involve addressing the various aspects of steel production and utilization, namely sustainability based on life cycle assessments (LCAs). The Swedish steel makers took the pioneering national initiative towards a more holistic view on steel production and use. The initiative was funded by the Swedish Foundation for Strategic Environmental Research and co-funded by Swedish steel industries. The programme, named the ‘Steel Eco-cycle’, had the vision closing the loop in the manufacture and use of steel in society. The programme had a multi-disciplinary approach, built around a network of projects with researchers from universities and institutes, environmental specialists and industry sectors participating. The programme envisaged a total optimization of the steel eco-cycle from development of newer steel grades to utilization of steel scrap, thereby retaining the metal values in alloy steels, minimizing losses and recovering valuable metals from slag and dust. Another important objective of the programme was to upscale the process ideas, make industrial tests and eventually implement them in industry. A number of processes developed under this programme are currently being commercialized. The paper will present the steel eco-cycle programme concept and development for a number of innovations.

Dilatometric Study of Phase Transformations in Steels: Some Issues

Abstract Dilatometry is widely used in the investigation of phase transformation in steels, not only by research laboratories but also by most steel makers. Its application includes the determination of CCT and TTT diagrams, and more generally the investigation of phase transformation kinetics under controlled temperature conditions. A basic and often undiscussed assumption in the exploitation of dilatation measurements as a function of temperature is that of a constant and uniform temperature distribution in the specimen, and of a homogeneous material. In the present paper, various issues encountered with a widely used quenching dilatometer were discussed, including longitudinal temperature gradients, deformation anisotropy, or vacuum evaporation of some chemical species.

Corrosion Properties of High-Corrosion-Resistance Galvanized Steel Sheet, Posmac(R)

POSCO, one of the leading-edge steel makers in the world, recently launched a new high-corrosion-resistance galvanized steel product under the name of POSCO Magnesium Aluminum alloy Coating (POSMAC®). POSMAC® is considered to have superior corrosion resistance due to extra metal compositions in galvanic layer, which contains about 3% magnesium and 2.5% aluminum. POSMAC® with relatively thinner galvanic layer could replace heavy-galvanized steel thanks to excellent cut-edge corrosion properties. This new product is used for various applications and chromate or Cr-free coatings are applied to enhance corrosion resistance. Chromate coating is not favored nowadays for health and environmental issues. However, regulations regarding chromate usage are different for regions and trivalent chromate is still allowed even in some countries that prohibit hexavalent chromium. We tested several chromate coating compositions on POSMAC® and tried to determine best compositions for various applications. Darkening (blackening) as well as normal corrosion properties of chromated POSMAC® was tested according to chromate coating composition, especially hexavalent and trivalent chromium concentrations. Cr-free coating is mainly used for applications that require relatively better corrosion resistance against white rust formation such as electronic devices, where aesthetic property is also important. Corrosion resistance of Cr-free coating POSMAC® is enhanced by modifying coating compositions. Various techniques were used in this study to determine corrosion properties, i.e. salt spray test (SST), cyclic corrosion test (CCT), cut-edge corrosion test, etc. Several analytical techniques were used to investigate corrosion and anti-corrosion mechanism by chemical coatings.

On the Aqueous Recovery of Zinc from Dust and Slags of the Iron and Steel Production Technologies

Recently the iron and steel makers as well are much more concerned with the by-products and waste streams generated in their ferrous metallurgical industries. In general, the relevant minor or trace elements (Si, Mn, P, Al, S, As, Cu, Zn, K, Na, Ti, Cr, V, W etc.) are not concentrated very much in the different slags and dust produced and collected during the subsequent processing steps of iron and steelmaking. However, zinc can be an exception, especially when zinc containing (e.g. hot dip galvanized) steel scraps are recycled in electric arc furnaces (EAF) to produce new unalloyed steels.

Mathematical Modeling of Inclusions Deposition at the Upper Tundish Nozzle and the Submerged Entry Nozzle

Nozzle clogging is still a concern for steel makers due to the high-quality requirements and productivity in the continuous casting. The present work studies the factors involved in the inclusion deposition at the nozzle wall using numerical and analytical techniques. For this, a detailed fluid dynamic analysis inside the nozzle in a coupled tundish–mold system is undertaken. The results show that the inclusions reaching the nozzle, only 30% get deposited along its walls mainly at the upper tundish nozzle (UTN) and at the submerged entry nozzle (SEN) ports. These areas of higher deposition are identified close to a low static pressure and a high turbulent kinetic energy dissipation zones. The high-energy dissipation induces a fluctuant velocity increment; consequently, the mean flow velocity increases forcing a reduction of the static pressure in order to preserve the mechanical energy balance. This mechanical energy imbalance is identified as mechanical energy dissipation being recognized by an increment in the vorticity and quantified by an additional term into Bernoulli equation. This complex phenomenon induces zones of high turbulent flow from which the inclusions tend to move toward lower turbulence regions, explaining why the inclusions get deposited in these two typical zones promoting the deleterious clogging phenomenon.

Measuring performance of sustainable manufacturing with recyclable wastes: A case from China’s iron and steel industry

Abstract In recent years, performance evaluation of sustainable operations has attracted a significant amount of research. The current paper seeks to evaluate sustainable manufacturing performance when wastes are recycled and re-used. For example, a typical sustainable process in iron and steel making involves in the first stage forging iron and steel products and in the second stage disposing the wastes. The sustainable manufacturing process then re-uses the recycled waste water in the first stage production. It is important that performance metrics include the operations related to recycling and re-use of the wastes. In a simplified view, such a sustainable operation is a two-stage process. Due to the ability of incorporating multiple performance metrics, data envelopment analysis (DEA) is used to develop our evaluation approach. While traditional DEA treats such two-stage manufacturing process as a black box by ignoring the internal conflicts and cooperation among multiple manufacturing stages, this paper proposes a modified two-stage network DEA model that deals with good and undesirable outputs from the sustainable manufacturing process. A Nash bargaining game between efficiencies of two-stages is proposed to produce unique and fair efficiency decomposition for the two-stage sustainable manufacturing process. The modified two-stage network DEA model is applied to wastewater recycling and reusing in a set of iron and steel makers in China. The results show that the proposed model is more effective than the black box DEA model in calculating efficiency of both two-stages and in identifying the sources of the inefficiency of overall sustainable manufacturing processes.

Chemical, Thermal and Phase Analysis of Malaysia’s Electric Arc Furnace (EAF) Slag Waste

This study aims to characterize and investigate properties of EAF slag waste obtained from Southern Steel Berhad, Penang (one of Malaysia’s largest steel makers), prior to its recycling into valuable products. Before characterization, lump form of the EAF slag was crushed into micron size powder. The properties investigated were loss of ignition (L.O.I.), chemical composition, leaching behavior, thermal properties and mineral phases present. Through XRF characterization, the chemical composition of the EAF slag was obtained. The slag was found to have extremely low L.O.I. (0.01 wt.%). Leaching test proved the slag is non-hazardous and safe to be handled. Meanwhile, thermal analysis (TGA) revealed the EAF slag is thermally stable and unlikely to decompose upon heating. Phase identification and quantification were performed by applying Rietveld refinement method. The EAF slag consisted of gehlenite (Al2O3.2CaO.SiO2 – 45.3 wt.%), larnite (2CaO.SiO2 – 21.0 wt.%), hematite (Fe2O3 – 13.4 wt.%) and wustite (FeO – 20.3 wt.%) mineral phases. The XRD profile fitted well with agreement indices of the refinement (Rwp: 6.658 and GOF: 2.588). The properties investigated in this study are expected to shed lights in evaluating the potential recycling of the EAF slag into various valuable products such as aggregate, brick, ceramic tile and cementing material.

Characterization of EAF Steel Slag Waste: The Potential Green Resource for Ceramic Tile Production

Abstract This study aims to characterize and investigate properties of electric arc furnace (EAF) steel slag waste to ensure its compatibility and suitability in ceramic tile production. Initially, the lump form of EAF slag obtained from Southern Steel Berhad, Penang (one of Malaysia's largest steel makers) was crushed into powder. The slag powder was then characterized in terms of loss of ignition (L.O.I.), chemical composition, leaching behaviour, phase analysis and flow button test. The EAF slag was found to have superior low L.O.I. (0.01 wt.%). In terms of chemical composition, the slag mainly consisted of oxides such as Al2O3, CaO, MgO, SiO2, FeO and Fe3O4, which are similar with typical raw materials (clay, silica and feldspar) for ceramic tile production. CaO based complex oxides such as larnite (2CaO.SiO2) and gehlenite (Al2O3.2CaO.SiO2) were the major mineral phases in the slag while wustite (FeO) and magnetite (Fe3O4) were present as the minor phases. From flow button test, it was observed that the EAF slag began to fuse at 1250 °C. Leaching test revealed that concentrations of the heavy metals leached from the EAF slag in both tap water and rain water conditions were lower than the limit regulated by Department of Environment (DOE) Malaysia. Thus, the slag could be considered as non-hazardous and it is safe to be utilized as one of the raw materials for ceramic tile production. Future studies will focus on body formulation and properties of the ceramic tile incorporated with the EAF steel slag waste.

Comprehensive Analysis to Specify a Static Var Compensator for an Electric Arc Furnace Upgrade

This steel maker is upgrading the electric arc furnace (EAF) melt shop to increase production and improve metallurgical quality of their product. The increased electrical load and harmonic generation for the new furnace operation necessitated the installation of a static var compensator (SVC) to meet utility interconnect requirements. This paper describes a sequence of comprehensive analysis performed to specify the SVC including load flow analysis, flicker analysis, and harmonic analysis studies. The analysis presented in this paper sized and evaluated the proposed SVC reactive compensation to mitigate flicker, harmonics, and power factor for the new EAF and ladle melt furnace installations to comply with the utility interconnect requirements.

Study on the evolution mechanism of oxidation and copper diffusion and precipitation phenomena and their effect on the surface quality of steel plates

Purpose – 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. Design/methodology/approach – 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. Findings – 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. Research limitations/implications – 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. Originality/value – 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.

Designing of Sub-entry Nozzle for Casting Defect-free Steel

Production of defect-free steel is a continuous demand for each & every steel maker. The design of refractories used in steel making process has a vital role on this. Manufacturing of cleaner steel is mostly attributed to the continuous casting process of the steel plant. Defects in steel mainly come from the non-metallic inclusions present in steel that are incorporated during various steel making process. During continuous casting, the main focus is to remove these inclusions to cast defect free steel. The flow pattern of molten steel in the mould plays a vital role in the removal of these impurities. The turbulence of the flowing steel in the mould should be such that more and more impurities will be floated at the meniscus of the mould and they will be captured by the casting powder. But, this turbulence should not be higher enough to capture the particles of casting powder inside the molten steel. So, in order to optimize the turbulent intensity and to get uniform distribution of temperature and velocity in the mould, the design of Sub-entry nozzle (SEN) is very crucial. SEN is used to guide the flow of steel from tundish to mould during continuous casting. The bore configuration and outlet design of SEN along with its immersed depth in the mould determine the flow pattern of steel inside the mould, which is the key factor to produce cleaner steel. This paper focuses on the different designing aspects of SEN to get an optimized and uniform flow of steel in the mould. The designing parameters include bore diameter, bore configuration, port shape, port angle, port dimension, number of ports and immersed depth of SEN inside the mould. Design optimization is done to improve the steel quality by removing the impurities.

Nanostructured steel industrialisation: plausible reality

It is not the first time that a consortium of steel makers, end users and scientists end up with unique approaches and developments in the physical metallurgy of steels. The present paper reveals the scientific and technological developments of a consortium sharing a common intrigue and interest for a unique microstructure, nanostructured bainite. Also known as low temperature bainite, its unique properties rely solely on the scale of the miscrostructure obtained by heat treatment at low temperature (150–350°C). Careful design based on phase transformation theory, some well known metallurgy facts and the necessary industrial experience were the ingredients for a further step towards the industrialisation of these microstructures.

Assessment and Risk Management of Potential Hazards by Failure Modes and Effect Analysis (FMEA) Method in Yazd Steel Complex

Background: Failure mode and effect analysis (FMEA) is a widely used quality improvement and risk assessment tool in manufacturing. The aim of this study is to assess potential hazards by failure modes and effect analysis (FMEA) method in Yazd Steel Complex. Methods: In this descriptive study, we evaluated the risks in different parts of the complex by using FMEA method and by using FMEA Worksheets (PFMEA) derived from the standard (MIL_STD-882). Failure modes and the various components and effects as using quantitative score to the risk priority (RPN) were obtained. PFMEA worksheets were completed and, we reevaluated the weaknesses part of the system. Activities related to each from the different parts of Yazd Steel Complex by using the scores risk priority (RPN) were evaluated. Then the results obtained by using SPSS software were performed by evaluation and analysis. Results: The findings showed that the steel maker lime unite and steel making ingot casting achieved the highest of RPN before and after corrective actions measures (490, 168) and environmental health unite and roll styles unite achieved the lowest of RPN before and after corrective actions measures (28, 20). Conclusions: The results show that the FMEA technique can identify a higher number of hazards than any other technique. The important point is that selection of an appropriate technique plays an important role in identifying a higher number of hazards.

Challenges and Opportunities for Long Product Speciality Steels in India

Metallic and operating cost as well as specific energy consumption are the key to long term viability of steel plants. Usha Martin achieved the highest directly reduced iron (DRI) rotary kiln campaign life which is a good case study for Indian steel makers who consume large quantities of DRI produced through the rotary kiln route. The factors affecting rotary kiln life and how the kiln life was extended at M/s Usha Martin have been elaborated in this study. Energy optimizing furnace (EOF) has good potential for steelmaking in India and it is technically and commercially viable with indigenously available raw materials. The advantage of EOF in the Indian context especially for mini steel plants not having captive mines is highlighted.

Determination of Ms temperature: methods, meaning and influence of ‘slow start’ phenomenon

Knowledge of the martensite start temperature in low and medium alloy steels is of critical importance for steel makers, or any industry involved in the transformation of hardenable steels. Its determination is often carried out by length change measurements in quenching dilatometers. The present paper focuses on the meaning of the information obtained in these experiments and discusses two alternative methods and their respective benefits, particularly with respect to the phenomenon sometimes referred to as ‘slow start’ for the martensite transformation.

Effect of Steel Making Slag on Castability of Medium Carbon Re-Sulfur Steel Grades

Abstract. One of the everlasting problems existing in alloy steel plant is clogging of Submerged Entry Nozzle(SEN) due to accumulation of De-oxidized/Re-oxidized products while casting Medium Carbon Re-Sulfur Steel grades(forging grades).After complete De-sulphurization and De-oxidation, liquid steel have been subjected to Ca-treatment which promote deep De-oxidation and deep De-sulphurization in addition to inclusion morphology control. Finally liquid steel have been injected with sulfur cored wire for chemistry requirement of 0.02-0.035%. All these conditions encourage thermodynamically favorable conditions for formation of various combination of oxide and sulphide inclusions which are highly detrimental to castability in continuous casting of integrated steel mill. This becomes one of the major process interruptions which directly terminate production capacity day by day and also affects the quality of cast product. As well said before “Best Slag Maker Is Best Steel Maker”, we mainly focused on secondary steel making slag at different stages, and found the relation of castability with respect to slag behavior. We arrived at optimal slag nature for better castability in continuous casting of steel.

Environmental Conservation Efforts and Byproducts Recycling Technologies of JFE

JFE is the fifth largest Steel maker in the world with revenue excess of US$ 3 billion. It is committed to creating a more sustainable society through business operations in harmony with the environment. JFE Steel continuously strives to reduce the environmental load in the steelmaking process, resulting in the company’s extensive recycling of energy, water, and other byproducts. This paper reviewed the environmental conservation efforts achieved by JFE Steel. The treatment and recycling techniques of different metallurgical waste and byproducts (such as dust, slag and sludge) were also described in details. At last, the author put forward some expectations for the development of the China's steel companies.

New Development and Application of Microalloyed Medium Carbon Steel for Auto Forging Products

Microalloyed medium carbon steels have been applied for auto forging products at the aim of lower cost since 1980’s in China. Without quenching and tempering processes, the cost of heat treatment was greatly decreased, so they are widely applied in car forgings such as crankshaft, connecting rod. Recently, with the aim of improving performance and reducing production cost, new technologies, such as: reductions of microalloyed elements, tailored components, and mechanical properties forecast, have been developed in China auto industry. The designation, processing, properties prediction and microstructure of auto components have been controlled comprehensively. With the development of new technologies, microalloyed medium carbon steel gradually began to be applied to product important parts, and replace Quenching and Tempering steels. Both steel makers and end product users are expressed their desire to share benefits of technological innovation. The technologies will have a huge developing space and very bright developing prospects in motor parts industry in future.

Numerical Study on Effect of Nozzle Diameter on Plate Cooling in Run Out Table of Hot Plate Rolling Process

The design of cooling systems for running hot steel plates has received much attention because the mechanical and/or metallurgical properties of final products are greatly influenced by the cooling capacity of the system. Thus many steel makers have largely concentrated on simply increasing the cooling water supply capacity of the system. Some researchers believe that plate cooling is a type of thermal communication between the hot plate and the cooling water or the atmosphere, so they have emphasized the importance of thermal conditions such as the cooling water temperature or air humidity. Actually the cooling process is governed by the basic physics of boiling heat transfer between the hot steel plate and the cooling water. Therefore steel makers should be more concerned about the influence of the design parameters of cooling facilities on the boiling phenomenon rather than the simple increase of the cooling water flow rate. In this study, when the diameter of the nozzle supplying cooling water is changed, its effect on boiling heat transfer has been investigated numerically. The average heat flux, the Leidenfrost-steam-layer thickness, the temperature drop and so on were investigated according to nozzle diameter.