BHP Steel Research Articles

Role of Mn and P in Texture of Bake Hardening Steel during Heat Treatment

Samples of three ultra-low carbon bake hardening (ULC-BH) steels (BH-0, BH-Mn, and BH-P) were prepared by two annealing processes followed by water quenching and overaging. The texture evolution in the as-treated steels was explored via EBSD and ODE, and the roles of Mn and P elements as well as heat treatment processes in the texture orientation and intensity were investigated. It is found that overaging significantly increases texture intensity of BH-0 and BH-Mn steel, while markedly hinders the texture development in BH-P steel. Based on the microstructure analysis, it can be deduced that the texture variations in BH-0 and BH-Mn steels mainly contribute to carbide (in BH-0 and BH-Mn steels) and manganese containing compound (in BH-Mn steel) or partially to C segregation to dislocation, while the texture variation in BH-P steel is mainly caused by the P and C co-segregation formed during quenching.

Variation of solute distributions during deformation and bake hardening process and their effect on bake hardening phenomenon in ultra-low carbon bake hardening steels

Three-dimensional atom probe was used to investigate solute carbon and other elements distributions during bake hardening process after pre-deformation and also to analyze their effect on bake hardening phenomenon of the steels. Two different kinds of bake hardening steels were prepared and annealed by water quenching. The as-received samples were pre-deformed at different levels (from 0 to 10%), and baked at 170 °C for 20 min. Distributions and concentrations of solute elements in the steels were characterized with three-dimensional atom probe. Bake hardening values of the steels were examined by tensile experiments. Three dimensional atom probe detection results indicate that C distribution changes little with the increase of pre-deformation in BH-Mn steel. In BH-P steel, however, with the increase of pre-deformation, more C clusters form in the matrix and C concentration decreases. Distribution patterns and the maximum separation distance method results prove that the C cluster is just C segregation or C together with P segregation rather than vanadium carbides precipitate. Moreover, bake hardening experiment results indicate that BH values are similar in the two BH steels and the BH values change only a little as the pre-deformation increases from 2 to 10%. The 4% pre-deformation induces the highest BH values in the two BH steels, and is considered to be the critical pre-deformation in making the balance of Cottrell atmosphere in the two BH steels.

Three dimensional iron flow and heat transfer in the hearth of a blast furnace during tapping process

The aim of this research is to numerically simulate iron flow and heat transfer in the hearth of a blast furnace by solving the three-dimensional turbulent Navier–Stokes equation coupled with the transport equation of energy at steady state. Under the effects of conjugate heat transfer and natural convection, a computational fluid dynamic calculation was performed to generate flow field in the hearth and the temperature distribution in the refractories during the tapping process. The accuracy and computation of the model is validated using operation data from BHP Steel's No. 5 blast furnace. The shear stress and heat flux on the wall were then predicted for the different vertical movements, shapes of the coke zone (dead-man), and the lengths of the tap-hole. As shown in the results, it is worth noticing that an increase in the tap-hole length causes the peak values of shear stress to shift in the increasing azimuthal direction at a particular plane, and the location of the peak value of shear stress coincides with the location of higher temperature actually measured on the hearth wall, signifying enhanced heat transfer to the wall at location of peak stress.

Recent progress on commercialization of castrip� direct strip casting technology at Nucor Crawfordsville

The world’s first commercial installation for direct casting of low-carbon steel sheet utilizing CASTRIP® technology is undergoing production ramp-up at Nucor Steel’s plant in Crawfordsville, Indiana. Construction of the plant was initiated in February 2001 and the first ladle was delivered to the caster in May 2002. Since that time, Nucor Steel has been working with technology partners BlueScope Steel (formerly BHP Steel) and IHI (Ishikawajima-Harima Heavy Industries) to fully commercialize this exciting new technology for the direct production of steel sheet less than 2 mm in thickness.

Numerical modelling of iron flow and heat transfer in blast furnace hearth

The erosion of hearth refractories is widely recognised as the main limitation for a long campaign blast furnace life. Distributions of liquid iron flow and refractory temperatures have a significant influence on hearth wear. In this investigation, a comprehensive computational fluid dynamics model is described which predicts the fluid flow and heat transfer in the hearth; specifically, the flow and temperature distributions in the liquid iron melt, and temperature distributions in the refractories. The accuracy and representativeness of the model was evaluated using plant data from BHP Steel's Port Kembla no. 5 blast furnace and OneSteel's Whyalla no. 2 blast furnace. Generally, there is good agreement between measured and calculated refractory temperature profiles. A series of sensitivity tests provided cause-effect relationships between operational and fluid flow parameters (floating deadman, different extent of refractory erosion, presence of embrittled layer).

Flow Characteristics of a Blast Furnace Taphole Stream and Its Effects on Trough Refractory Wear.

An investigation consisting of plant trials and water modelling studies has been carried out with the aim of gaining a better understanding of flow characteristics of a blast furnace taphole stream and its effect on the trough refractory wear. It has been found that the entrainment of the blast gas into the taphole is the most likely root cause for splashy taphole stream, which is believed to greatly contributes to refractory wear on the trough in the region above the liquid level and on the trough cover. Based on the findings from the present studies, changes were made to furnace operation and casting practices at BHP Steel's Flat Products Division No. 6 Blast Furnace (BF6) to minimise splashy taphole streams. As a result, the refractory wear on the trough and its cover has been significantly reduced. The trough cover life of BF6 has been improved, from 60 000 to 300 000 tonnes of hot metal.

Design and implementation of slag practices for reduction in refractory consumption at BHP steelmaking centres

BHP Steel produces about 8 million tpa of steel for the local and overseas markets. The costs associated with refractory materials are considerable and thus strategies have been developed to reduce the refractory wear in steelmaking operations. The approaches developed take into account some of the key fundamental factors influencing the metallurgical performance of the process and the rate of chemical attack of refractories by molten slags. Thermodynamic models have been used for analysis of plant data and design/tuning of suitable practices to prolong the refractory life via in‐situ coating of refractories with solid phases with high resistance to slag attack. Examples of the results obtained from implementation of such practices are presented.

From EDI to Internet commerce: the BHP Steel experience

Discusses the issue of business‐to‐business e‐commerce implementation and the factors affecting it, considering the appropriateness of the various theories which underpin research into systems implementation (primarily diffusion of innovation and traditional change management theory). Describes the results of a case study of BHP Steel, the largest steel producer and one of the largest companies in Australia, which is a leader in e‐commerce implementation. The results suggest that, over time, the driving force for e‐commerce changed significantly. From an initial push to improve current business processes by adopting EDI to achieve savings and improve efficiency, the company came to be driven by a desire for greater supplier involvement and customer service in later implementations. Discusses the ways in which BHP Steel’s e‐commerce innovations have changed and suggests that, in addition to considering the characteristics of the innovation process, other more contextual aspects of implementation (such as the social system in which the innovation evolves and the timing of the innovation’s introduction) be considered in an inter‐organizational context.

Preliminary study on the application of steel industry slag for phosphorus removal in Constructed Wetland

Industrial waste by-products has been found to be suitable for using as a substratum in CWS (Constructed Wetland System) as it absorbs phosphorus (P as orthophosphate) to a greater extent than sand, soil or gravel matrices. In this study, the possibility of using the slag (waste by-products obtained from BHP steel industry, Australia) as a flocculant (in-line adsorbent addition) was investigated in the batch flocculation experiments. P removal efficiency increased with the increases of the flocculant dose, mixing rate and pH. The pH in the supernatant of the P solution kept increased up to intrinsic pH of the flocculant. This increase was proportional to the flocculant dose and its time. The given sample was introduced for the possible application of upgrading the sewage treatment plants with CWS. The economical feasibility and toxic materials discharge are found to be important factors for the application of this system. A brief discussion was introduced on the use of the slag to suppress P liberation from sediment which is one of major causes for eutrophication of closed water bodies.

Controller design for hot strip finishing mills

The results to date of a collaborative research project with BHP Steel in Port Kembla, Australia, are described. The project is concerned with control of strip tension and looper angle in BHP's hot strip steel rolling mill (the finishing mill). The new controllers have been successfully implemented on the process and now handle all the production at the mill. The paper describes a model of the process, similar to that reported in the work of others. The development of a full nonlinear controller is traced, based on a recursive nonlinear method (cf., backstepping). Insights are drawn into possible system structures, particularly in the output feedback case when tension measurements may not be available. Alternative controller schemes are examined, including a speculative design which contains filters, similar to those obtained from output feedback designs of linear systems, together with nonlinear operators which invite comparisons with variable structure designs. Simulation results, which provided the justification for the final implementation, together with results from actual production records are presented.

Evaluation and Control of Employee Exposure to Diesel Particulate at Several Australian Coal Mines

Abstract Employee exposures to diesel particulate (DP) were measured under normal and abnormal mining operations at BHP Steel Collieries Tower Colliery and other underground coal mines in New South Wales coal fields. DP was measured using submicron samplers developed by the U.S. Bureau of Mines, and the results were verified using quantitative scanning electron microscopy. Personal monitoring (n = 480 full-shift samples) conducted at nine underground coal mines has indicated that the exposure of the work force ranges from less than 0.1 to 2.2 mg/m3 of DP, depending on job type and mining operation. Operations such as longwall moves and stonedusting, which generate elevated levels of dust, cause severe interference to submicron DP measurements. Based on previous knowledge that engine tune and condition affect the balance between gaseous and particulate emissions, five technologies for controlling DP were investigated in a combination of studies conducted in an above-ground simulated tunnel and in a special controlled section of underground mine roadway. Potential improvements were validated by application in standard coal mining operations at Tower Colliery. Tests conducted under controlled conditions indicate that, depending on fuel quality, levels of DP in return airways can be reduced by up to 50 percent, and in actual mining situations a reduction of 20 percent can be achieved in exposure of the work force by the use of low sulfur fuels. In addition, subjective responses from the work force indicate that exhaust emissions from low sulfur fuels provide lower irritation and a more pleasant aroma. The use of water-filled scrubber tanks reduces the level of DP emissions by 25 percent. In addition, it was found that the cleanliness of these tanks in general does not affect their scrubbing properties. Chemical decoking of engines resulted in a reduction of 20 percent in DP in return airways. However, the longterm benefits and cost effectiveness of this treatment in mining operations have yet to be established. A nonflammable, disposable dry exhaust filter constructed from synthetic organic fibers with an operational lifetime in excess of 20 hours was found to reduce DP exhaust emissions by 80 percent. Investigations have indicated that the use of increased ventilation to control DP levels does not follow a simple dilution factor, and in some instances compliance with current regulatory requirements may not produce the required reduced exposure levels. The results from single-component control strategies provide considerable reduction in exposure to DP. However, the most efficient and cost-effective control methodology is the use of a combination of individual systems modeled to operations conducted at each mine.

Design Study for Continuous Caster Tundish Weight Control and Ladle Steel Flow Estimate

Abstract This paper describes a study into tundish weight control and steel flow estimation at BHP Steel - Long Products Division, Newcastle, NSW, Australia, performed during late 1995. Following upon a previous project to successfully implement automatic mold level control at this installation, a study was made on how to improve the weight control in the tundish and to also improve the estimate of steel flow exiting the ladle. The project involved plant analysis, controller design, Kalman filtering and on-line implementation. The feasibility study successfully achieved its objectives and resulted in some modifications to the existing control system.

A Detailed Investigation of Phosphorus Removal in Soil and Slag Media

Kinetic studies on phosphorus (P as orthophosphate) sorption onto a sandy loam soil from North Sydney, Australia, and a slag (waste products from the BHP steel industry, Australia) revealed that more than 90% of the P was adsorbed within 70 and 12 hours for the soil and slag respectively. The pH of the P solution played a critical role in the rate of P removal. Removal was at a minimum at pH 2. Dominant removal mechanism of P at pH less than 8 was physical sorption, while it was chemical precipitation at pH greater than 10. Adsorptive capacity of the slag was 225 and 53 times of that of the soil for the static and dynamic systems respectively. Breakthrough curves obtained from the column experiments are S-shaped and more spreaded with the decrease of influent P concentration. Simulated results from an equilibrium sorption model (ESM) and Freundlich isotherm constants did not always match the corresponding experimental breakthrough data. Mobility of P is restricted by the adsorbent due to its high sorption capacity of P.

PREPARATION AND IMPLEMENTATION OF A SAFETY MANAGEMENT SYSTEM IN BHPP

BHP is a leading global resources company which comprises four main business groups: BHP Copper, BHP Minerals, BHP Steel and BHP Petroleum. BHP Petroleum (BHPP) global operations are divided into four Regions and Australia/Asia Region is responsible for exploration, production, field development and joint ventures in the Asia-Pacific region. In Australia, the Company's largest producing assets are its shares of the Gippsland oil and gas fields in Bass Strait and the North West Shelf project in Western Australia.BHPP operates three Floating Production, Storage and Offloading (FPSO) vessels-Jabiru Venture, Challis Venture and Skua Venture-in the Timor Sea and one FPSO, the Griffin Venture, in the Southern Carnarvon Basin. Stabilised oil is offloaded from all four FPSOs by means of a floating hose to a shuttle tanker. Gas from the Griffin Venture is compressed and transferred through a submarine pipeline to an onshore gas treatment plant.BHPP's Asian production comes from the Dai Hung oil field offshore Vietnam where BHPP is the operator and from Kutubu in Papua New Guinea.In Melbourne, BHPP operates a Methanol Research Plant and produced Australia's first commercial quantities of methanol in October 1994.BHPP is an extremely active offshore oil and gas explorer and has interests in a number of permits and blocks in the Australian-Indonesian Zone of Co-operation.This paper discusses BHPP's approach to safety management, both for its worldwide operations and specifically in Australia/Asia Region. It explains how BHPP's worldwide safety management model takes regional regulatory variations into account. It shows, specifically, how this has been done in Australia/Asia Region using what BHPP considers to be a best practice approach.The paper describes how BHPP Australia/Asia Region benchmarked its performance against other operators in Australia and the North Sea. It explains how the findings of the benchmarking study were used to plan the preparation of a safety management system (SMS). The structure of the SMS is described along with the legal requirements in Australia.The paper concludes that implementation of the SMS is progressing according to plan and points out that safety cases for the FPSOs have been submitted to the Regulators. Implementation of the SMS and the drive for world class safety standards is having a substantial effect and safety performance is improving. One measure of safety performance, the Lost Time Injury Frequency Rate (LTIFR) is down from around 15 at the end of 1994 to under 3 in December 1996.

Discharge Slab Temperature Estimation

This paper reports on a new approach to the temperature sensing of hot slabs of steel at the discharge of a reheat furnace and during the rolling process. Thissoft-sensortechnique uses the measured rolling forces as the raw information for temperature estimation and relies on the existence of accurate rolling and cooling models for the roughing mill. Some results on the application of this slab temperature estimator using operational data from BHP Steel’s Western Port Hot Strip Mill are presented.

Using Seismic Data and Cross-Hole Analysis to Image Fractures

Two stratigraphic bore-holes 335 m apart, drilled to the Bulli coal seam at a mine site in the Southern Sydney Basin, showed an average velocity discrepancy of 10 per cent throughout the entire lithological section. Subsequently, a comprehensive seismic experiment was performed by BHP Steel (AIS) Pty. Ltd. Collieries Division which included the surface seismic reflection, walk-away vertical seismic profile (VSP) and cross-hole recording over the area connecting the two bore-holes. The surface seismic data indicated possible seam disturbances between the bore-holes. The VSP data were of variable quality, while cross-hole data were of the best quality. Strong transverse isotropy was measured through the sandstone unit. The top 100 m of the Bulgo sandstone showed weak P-wave anisotropy. However, shear wave splitting in the Bulgo sandstone suggested fracture induced anisotropy. Methane accumulations were inferred from the reflection and VSP data and Poisson's ratio computed at the receiver borehole. Analysis of these data revealed a high complexity of the zone between and away from the boreholes. The poor quality of reflection and VSP data resulted from the presence of faults, associated fractures and several methane accumulations in the Bulgo sandstone. The overall velocity difference between the boreholes is related to a change in stress field. The results of the experiment showed that where reflection seismic data was poor, the application of three component VSP and cross-hole seismic data can be used to define a structurally complex area which may contain faulting/fracturing and methane. In such areas special care has to be taken in data processing, analysis and time to depth conversion.

Eliciting knowledge for material design in steel making using paper models and codification scheme

Knowledge elicitation (KEL) is the most important stage, but often the principal bottleneck, in the development of knowledge-based systems. Due to the difficulties faced in the knowledge-elicitation process, development of a knowledge-based system for material design in the steel-making industry is a complex task. An attempt is made in this paper to present a new approach to deal with knowledge elicitation for material design problems in the steel-making industry. This paper centres around the human aspects and is based on practical experience gained while developing a knowledge-based system for material design at BHP Steel, Australia. This approach involves codification of the customer's special requirements to identify the knowledge sources involved in the design process. This is followed by the use of paper models to improve the efficiency of the KEL process. The second stage of the structured interviews is based on the customer's special requirement codes for eliciting the missing information and for clarifying any ambiguities or inconsistencies. The paper also discusses the use of non-interviewing techniques to elicit the expert knowledge, in order to reduce the use of expensive interview time. The knowledge-representation scheme developed for the material design system aims at reducing the search time and storage space by utilising a codification scheme to classify various knowledge sources into appropriate categories.

Business Process Redesign Using EDI: the BHP steel experience

EDI should not be seen as a competitive weapon - it does not offer a sustainable competitive advantage to its users as did the earlier inter-organisational systems (such as the various airline reservation systems). Instead EDI provides a standardised infrastructure upon which an adopting organisation can reengineer its business processes and thus confers a long-term, strategic and comparative advantage upon such an adopter. The potential for sustained competitive advantage to be derived from EDI arises from its integration with the organisational structure of its implementor, depending upon the implementing organisation's ability to redesign its business processes appropriately. This paper examines the case of (arguably) the most sophisticated EDI-using company in Australia, BHP Steel, demonstrating the advantages obtainable by an organisation using EDI as a foundation for its reengineered organisational structure and business processes and concludes that: • there are real benefits to be obtained from an inter organisational electronic trading strategy founded on EDI as the enabling mechanism - benefits which are considerably more extensive than EDI's comparatively simple technical nature would appear to offer; • organisational gateways utilising an Application Generic approach to system integration and isolating the communications issue by insisting on the use of international data communications standards do offer a realistic and successful solution to the problem of internal and external trade for large and sophisticated organisations; • the majority of these achievements would have been either unlikely or totally impossible without BHP Steel's commitment to organisation-wide Business Process Redesign.

A method of knowledge acquisition developed in the construction of DESPLATE

This paper describes a knowledge acquisition methodology developed in the construction of DESPLATE, an expert system for diagnosis of faulty plan view shapes of steel plates. DESPLATE is jointly developed with BHP Steel International Group, Slab and Plate Products Division. The project requires input of domain experts from several disciplines, namely, electrical engineering, mechanical engineering, rolling mills technology and operations. The methodology developed therefore involves multiple experts with different disciplinary backgrounds.

INDUSTRY

Setting the stage for market growth. Setting the stage for accelerated worldwide marketing of Galvalume, BHP Steel International Group, Australia, has recently acquired subsidiary, BIEC International, Inc., headquartered in Bethlehem. Both — BHP Steel International Group and BIEC are subsidiaries of Broken Hill Proprietary Co. Ltd. Australia's largest firm.