Showing papers by "Bethlehem Steel published in 1997"

Effect of the Ti/N ratio on the hardenability and mechanical properties of a quenched-and-tempered C-Mn-B steel

Abstract: Ten experimental 0.18 pct C-1.2 pct Mn- 0.002 pct B steels with various Ti/N ratios were evaluated in this study. The hardenability of these steels was first determined using Jominy tests. Slab sections were then rolled to produce 12.5-mm-thick plates, and subsequently quenched and tempered for mechanical property evaluation. The volume fraction of coarse (greater than 1 µm) TiN particles was measured in all steels using quantitative metallographic techniques. Scanning transmission electron microscopy was used to investigate fine precipitates, and scanning electron microscopy was used to examine the fracture surface of Charpy specimens. The results show that a complete boron (B) hardenability effect is obtained with Ti/N ratios ≥2.9, a value slightly below the stoichiometric Ti/N ratio of 3.4. Any excess Ti, above that which combines with N, provides an additional increase in hardenability on quenching (effect of Ti in solution) and an increase in strength on tempering (Ti (C,N) precipitation). Steels with a higher (Ti)(N) product develop a higher volume fraction of coarse TiN particles during solidification. These coarse TiN particles result in reduced toughness levels of the heat-treated plates evaluated in the present study.

Surface tension and wettability studies of liquid Fe-Ni-O alloys

Abstract: Surface tensions of iron-nickel alloys were measured as a function of oxygen potential at 1550 °C using the sessile drop technique. The surface tension of pure liquid nickel and iron-nickel alloys was measured at a total pressure of 1 atmosphere under varying CO2/CO ratios. An increase in the oxygen potential in the gas phase was found to correspond to a decrease in surface tension of pure nickel and iron-nickel alloys, indicating that oxygen is surface active in both liquid nickel and iron-nickel alloys. At low oxygen potentials, nickel additions to liquid iron were found to cause small decreases in alloy surface tensions; however, at higher oxygen potentials, the surface tension of the alloy exhibited a minimum value as nickel was added to iron. The adsorption coefficients of oxygen in liquid iron-nickel alloys and pure liquid nickel were determined from the surface-tension data using Belton’s analysis, and were found to be similar to those calculated from kinetic studies. Wettability of iron-nickel alloys on an alumina substrate was studied through contact-angle measurements. At a constant alloy nickel content, the contact angle between the alloy and alumina decreased with increased oxygen potential in the gas phase.

Composition and method for producing an alloy steel and a product therefrom for structural applications

Abstract: A high strength low-alloy steel is subjected to a controlled rolling and accelerated cooling process to obtain minimum physical properties while achieving improved mill productivity. The alloy chemistry utilizes a low silicon, carbon, niobium, vanadium, titanium-containing steel composition which is hot worked and accelerated cooled under controlled conditions. The chemistry, controlled rolling and accelerated cooling allows for significant increase in the finishing rolling temperature thereby permitting high rolling output. The alloy chemistry includes a low-carbon grade which also has improved castability, formability and weldability.

Inference equations for fracture toughness testing: Numerical analysis and experimental verification

Abstract: The currently codified fracture toughness testing procedures, e.g., ASTM E 813, E 1152, E 1290, and BSI 7448:Part 1 use a set of inference equations to obtain J and CTOD from the measurements of global displacement and load. These inference equations were originally developed by assuming homogeneous and perfectly plastic material properties. Inaccurate results may be obtained when these inference equations are applied to non-homogeneous specimens and materials with strain hardening. A systematic study of the relationship between crack driving force (J and CTOD) and the remote load and displacement is conducted using finite element method. The relationship derived from the study is compared with the inference equations used in the current standards. The accuracy of the currently codified J and CTOD inference equations and those proposed in recent years is examined. Compared with the codified inference equations, the new equations can be applied to a wide range of crack depth (0.1 {le} a/W {le} 0.5). The new CTOD inference equations provide much more accurate CTOD values for high strain hardening material than is possible using the current standards. The accuracy of the codified inference equations and the new equations is expressed in terms of weld width, strain hardening rate,more » and mismatch levels. The CTOD inference equations are tested through corroboration with experimentally measured values of CTOD in an unwelded HSLA structural steel. The new equations provide better agreement with the experimental measurements than the codified equations.« less

Development and application of an integrated neural system for an HDCL

Abstract: This study presents the development and industrial application of an integrated neural system in coating weight control for a modern hot dip coating line (HDCL) in a steel mill. The neural system consists of two multilayered feedforward neural networks and a neural adaptive controller. They perform coating weight real-time prediction, feedforward control (FFC), and adaptive feedback control (FBC), respectively. The production line analysis, neural system architecture, learning, associative memories, generalization and real-time applications are addressed in this paper. This integrated neural system has been successfully implemented and applied to an HDCL at Burns Harbor Division, Bethlehem Steel Co., Chesterton, IN. The industrial application results have shown significant improvements in reduction of coating weight transitional footage, variation of the error between the target and actual coating weight, and the coating material used. Some practical aspects for applying a neural system to industrial control are discussed as concluding remarks.

Method and apparatus for controlling galvanneal induction furnace operation

Abstract: A method for controlling operation of a galvanneal induction furnace includes the steps of providing a steel strip having a molten zinc coating applied thereto and transporting the strip to an induction furnace in which the strip and coating are to be alloyed The temperature which the strip is estimated to attain just prior to entering the furnace is then calculated A temperature which the strip should achieve during the alloying reaction is then selected The power which must be applied to the furnace to elevate the strip temperature from the estimated temperature to the alloying temperature is then calculated Power is then supplied to the furnace

High energy pump system for use in the descaling of steel

Abstract: This invention relates to a descaling system for use in the manufacture of steel and corresponding method, including a pump recirculation system. The recirculation system is adapted to make high pressure descaling fluid (e.g. water) instantaneously available to the descaling nozzles for spraying, and to maintain a temperature differential between the pump suction and pump discharge less than about 25° F. during both descaling and recirculation.

Planking and method of use

Abstract: The invention is directed to metal planking used to construct planar surfaces, such as patio, porch and balcony decks, and interior floors and roofs of structures. The metal planking comprises an elongated strut and a slidable cap that covers the strut after the strut is fastened to support members in the structure. The strut includes a first flange and first web spaced apart from a second flange and second web, and a cord extending between the first web and the second web. The cord provides a surface for fastening the strut to the support members of the structure, and the cord includes at least one corrugation extending in an upward direction to a location adjacent the plane of the first and second strut flanges. The slidable cap includes a first hem extending along one edge of the cap, and a second hem extending along the opposite edge of the cap. The first and second hems include a seam shaped to slidably receive either of the strut flanges so that the slidable cap can be pushed onto the flanges and slipped along a length of the strut to cover the strut after the cord is fastened to the support members.

Flame detection monitoring system for detecting blockages in blast furnace injection paths

Abstract: A flame detection system for detecting blockage in oil injection paths into blast furnaces utilized in the manufacture of iron. The flame detection system, as designed and installed, monitors the amount of light seen through a blowpipe peephole and causes an alarm to be actuated when a voltage falls below a predetermined threshold thereby indicating that the amount of light being received by a photocell mounted at the peephole is at a low enough level to possibly indicate injection path or port clogging. Efficient calibration circuitry and techniques are also provided.

The origin of striations on the surface of iron–zinc coated steel sheet produced by hot-dip galvannealing

Abstract: Dark striations are often observed on the surface of iron–zinc coated steel sheet annealed immediately after hot-dip galvanizing (galvanneal). The striations can be explained on the basis of the differential formation of an iron–aluminium barrier layer at the steel-bath interface during galvanizing. The contact of a submerged, grooved sink roll in the galvanizing bath with the steel sheet causes variations in the iron–aluminium barrier layer at the interface. A more coherent layer is formed in the areas where there is no contact i.e., the grooved areas on the sink roll. The growth of the iron–zinc coating under a higher local aluminium concentration during subsequent annealing leads to a pitted surface in those groove areas, and creates the appearance of dark striations on the surface of the coated sheet. The aluminium content of the galvanizing bath is a key factor in determining the extent of the non-uniformity imposed by the contact with the sink roll. Consequently the striations can be reduced by lowering the aluminium content of the galvanizing bath.

Apparatus for refurbishing a coke oven doorjamb

Abstract: A method and apparatus for refurbishing eroded portions in coke oven doorjambs including refurbishing apparatus having a framework attached to the coke oven structure adjacent the doorjamb. The framework supports a carriage that is simultaneously moveable in an "X" axis direction and a "Y" axis direction within the boundary so that a machine-cutting tool, attached to the carriage, can be moved from one position directly to another position within the framework boundary. The machine-cutting tool is positioned to make cutting passes alone new metal that is fused into the eroded portions of the coke oven doorjamb.

Effects of Composition and Heat Treatment on the Toughness of ASTM A508 Grade 3 Class 1 Material for Pressure Vessels

Abstract: A laboratory study was conducted to evaluate the effects of composition and heat treatment on the toughness of ASTM A508 Grade 3 Class 1 material for pressure vessels. Five steels were vacuum induction melted and cast as ingots in the laboratory. These heats included a base steel representing the specification mid-range analysis, a steel containing higher levels of Si, Ni, and Cr (high-side composition) as compared to the base steel, and three steels derived from the high-side composition by adding Al, Al/N, and Nb, respectively. The ingots were rolled to plate, heat treated, and evaluated. Among these steels, the high-side composition with additions of Al and N displays the best strength/toughness combination. For example, a 75 mm-thick plate of this steel has acceptable strength and a reference nil ductility transition temperature (RT{sub NDT}) of {le} {minus} 29 C after austenitizing at 875 C, air cooling, and tempering at 660 C for up to 20 hours. Upper-nose temper embrittlement (UNTE) occurs in all these steels. This UNTE is attributed to the precipitation of needle-like Mo-rich carbides during tempering, and is significantly reduced by increasing the cooling rate after austenitizing.

Fracture initiation by local brittle zones in weldments of quenched and tempered structural alloy steel plate

Abstract: The heat-affected zone (HAZ) embrittlement of an API 2Y Grade 50T quenched and tempered offshore structural steel plate, welded by the submerged-arc process at a heat input of 4.5 kJ/mm, was investigated from the viewpoint of identifying the local brittle zone (LBZ) microstructure and the metallurgical factors associated with its formation. Microstructural and fractographic analysis showed the LBZ microstructure to be dual phase martensite-austenite (M-A) constituent. The formation of M-A constituent was found to be related to microstructural banding of the hot-rolled base plate. When the banded base plate was welded, M-A constituent formed only within the band microstructure which penetrated the intercritically-reheated coarse-grain HAZ (IRCGHAZ). The chemistry of the band microstructure in conjunction with the thermal cycle of the IRCGHAZ provided the critical conditions for the formation of M-A constituent in the API 2Y Grade 50T steel investigated. The influence of local brittle zones (i.e., M-A constituent) on the HAZ fracture toughness was evaluated by means of Crack-Tip Opening Displacement (CTOD) tests. These tests showed the steel to suffer embrittlement when the fatigue precrack sampled an intercritically-reheated coarse-grain HAZ which contained M-A constituent, confirming that M-A constituent is the major microstructural factor controlling the HAZ toughness of this particularmore » steel.« less

Beam blanks for direct rolling as-cast into finished products

Abstract: Continuously cast beam blanks having an adjusted flange shaped to provide an (Aw/Af) ratio for direct rolling as-cast into an entire range of finish products in a family of structural shapes.

Adaptive disturbance estimation applied to harmonic disturbance rejection

Abstract: The work presented was motivated by a control problem dealing with regulation of molten steel level during continuous casting. The process is such that influx is controlled based on feedback (liquid-) level measurements and feedforward (solidified-) efflux settings. Regulation of the liquid level to set-point is crucial to the quality of the solidified product, and must be achieved in the face of unmeasured oscillatory disturbances. Therefore, a control design methodology was sought that could provide oscillatory disturbance rejection. The author presents a viable solution to an important design equation relative to system disturbance response. The solution is perfectly general, and can be easily extended to non-square system matrices by use of the Moore-Penrose generalized inverse. Furthermore, it is demonstrated through simulation that it is possible to effect harmonic disturbance rejection using proven linear control methodologies enhanced with adaptation. An ad-hoc parameter estimator is used, and it is found that the overall system response is sensitive to some inherent characteristics of the adaptation technique employed. Alternatively, use of more sophisticated parameter estimation algorithms or nonparametric estimation adaptation may lead to better overall response than is demonstrated herein.