Showing papers by "Bethlehem Steel published in 1980"

Niobium carbonitride precipitation and austenite recrystallization in hot-rolled microalloyed steels

Abstract: The response of austenites to thermomechanical treatments is studied in a series of niobium (columbium) HSLA steels. Interactions between composition, plastic deformation, strain-induced precipitation, and austenite recrystallization are described and related to previous work in the field. Niobium in solution prior to deformation leads to significant retardation of subsequent austenite recrystallization if Nb(C,N) precipitation takes place prior to or during the early stages of recrystallization. Such straininduced precipitation proceeds in two stages: initially at austenitic grain boundaries and deformation bands, and later on substructural features in the unrecrystallized austenite. The latter precipitation is accelerated only if it occurs in the unrecrystallized austenite; if recrystallization precedes Nb(C,N) precipitation, then the precipitation reaction is much slower. Thus, the Nb(C,N) precipitation and austenite recrystallization reactions are coupled phenomena. The conditions necessary for such an interaction are analyzed, and it is proposed that the level of supersaturation of Nb(C,N) in the austenite at the deformation temperature is a critical factor in determining whether or not an effective interaction will operate at that temperature.

Chemistry, microstructure, and reduction characteristics of dolomite-fluxed magnetite pellets

Abstract: The addition of dolomite to iron ore pellets improves high temperature reduction properties, primarily by increasing their softening point and reducibility. This study was made to ascertain the compositional ranges within which dolomite fluxed magnetite pellets show such an improvement over good acid pellets. A variety of compositions with MgO levels from 1 to 2 wt pct and CaO/SiO2 ratios of 0.6 to 1.8 were prepared using Hibbing magnetic concentrate. These compositions were balled and then pot-grate fired to various temperatures. Petrographic examination and electron microprobe analyses were used to characterize the phase assemblages. Reduction characteristics were also evaluated. As evidenced by the following petrographically observed relationships, the CaO/SiO2 ratio (c/S) was found to be the controlling factor for pellet microstructure: a) The low c/S ( 1.3) pellets were mostly calcium ferrite-bonded. Intermediate c/S compositions contain more magnesioferrite than do either low or high basicity compositions. Pellets must be fired to a high enough temperature to generate sufficient liquid for ion transport but not so high as to cause pellets to stick together. Well-fired pellets with a c/S of 1.3 or less performed adequately in low temperature degradation tests. Pellets with a c/S of 0.8 or greater displayed satisfactory swelling behavior. Therefore, we determined that pellets within a c/S range of 0.8 to 1.3 are technically acceptable. Pellets containing 1.5 wt pct MgO had the best reduction characteristics, but all fluxed compositions reduced faster and more completely than did acid pellets. Increasing MgO content up to 2.0 pct increased the softening temperature by 165‡C over acid pellets. On the basis of pellet test results and taking into consideration the auxiliary influence of economic and operating considerations, we determined the optimum composition of dolomite fluxed Hibbing pellets to be 1.5 pct MgO and a C/S of 0.8.

Optical attenuation monitor system and method

Abstract: Light operative apparatus is located inside electro-optical instrument viewing window, such as that used by a radiation pyrometer or dimensional gage in a steel mill environment, to detect and compensate for optically attenuating objects which may accumulate on the outside surface of the viewing window. Light beam irradiates viewing window from inside and optics collects light radiation backscatter which varies as a function of light-scattering attenuating objects that have accumulated on the viewing window outside surface. A light backscatter detector feeds display, alarm and instrument compensation functions.

Method of improving the ductility of the coating of an aluminum-zinc alloy coated ferrous product

Abstract: This invention relates to an aluminum-zinc alloy coated ferrous product whose coating is highly ductile, and to the method whereby such improved coating ductility may be realized. The process is characterized by the steps of thermally treating the aluminum-zinc alloy coated product by heating to a temperature between about 200° F. (93° C.) and 800° F. (427° C.) and holding for a period of time to effect metallurgical structure changes, among them being the precipitation of a second phase incoherent with the matrix, followed by slow cooling to at least 400° F. (205° C.). The resulting product is characterized by an aluminum-zinc alloy coating with a hardness no greater than about 115 VHN, and preferably no greater than about 110 VHN.

Culvert structure having corrugated ribbing support

Abstract: A low-profile culvert structure comprising in combination, a plurality of arch-shaped corrugated structural metallic sheets secured to each other in such a manner as to form an elongated shell having typically a low rise to span ratio, and a plurality of transverse reinforcing ribs, each in the form of a corrugated metallic sheet. The transverse reinforcing ribs are secured to said shell at intervals along the length thereof, preferably to both the interior and exterior of the elongated shell.

Microalloying effects in hot-Rolled low-Carbon steels finished at high temperatures

Abstract: As part of a program to improve the toughness of steels for structural shapes and thick plates, the effects of columbium (niobium) (0 to 0.24 pct) or vanadium (0 to 0.23 pct) in conjunction with aluminum (0 to 0.06 pct) on the properties of hot-rolled 0.1 pct carbon steels were determined. Experiments were conducted on a laboratory mill to obtain 25 mm (1 in.) plate. Although the primary interest was to improve toughness in materials finished above 980 °C (1800 °F), finishing temperatures in the range 845 to 1150 °C (1550 to 2100 °F) were investigated. Impact properties of columbium steels finished above 980 °C (1800 °F) were very poor. This effect was attributed to the presence of acicular Widmanstatten structures and relatively coarse grain-boundary precipitates. Toughness improved dramatically at finish-rolling temperatures of 955 °C (1750 °F) and below as a result of the combined effects of grain refinement and reduced precipitation hardening. For the vanadium steels, variations in finish rolling temperature did not have such a marked effect on properties. Aluminum additions considerably lowered the impact transition temperature of the vanadium steels. Although aluminum also improved the impact properties of the columbium steels, the effect was not sufficient to produce good toughness in steels finish-rolled above 980 °C (1800 °F). Thus, although superior properties may be obtained in the columbium steels finished below 925 °C (1700 °F), vanadium steels generally had better impact properties at higher finishing temperatures.

Method of producing an aluminum-zinc alloy coated ferrous product to improve corrosion resistance

Abstract: This invention relates to an aluminum-zinc alloy coated ferrous base product which exhibits improved atmospheric corrosion resistance, and to the process whereby such improved corrosion resistance may be realized. The process is characterized by the steps of heating such coated product to a temperature within the single phase region for the composition corresponding to the aluminum and zinc of said coating, defined as α in the FIGURE in the accompanying drawing, preferably at a temperature between about 650° F. (343° C.) to 750° F. (399° C.), for a period of time to solution treat the aluminum-zinc alloy coating overlay, and cooling slowly to at least 350° F. (177° C.). The resulting product is characterized by improved atmospheric corrosion resistance as a result of the combination of an aluminum-zinc alloy coating overlay having a structure comprised of a fine dispersion of beta-zinc within a matrix of alpha-aluminum, and a thin intermetallic layer interposed between said overlay and said ferrous base.

Method for measuring the thickness of a refractory in a metallurgical apparatus

Abstract: A method for measuring the thickness of a refractory laid-up against the interior surface of the steel shell of a metallurgical apparatus includes placing at least one monitoring device in a critical wear area of the apparatus in a manner such that the free end of the device is at a known distance from the hot face of the refractory and the confined end extends beyond the outer surface of the steel shell. The device is connected to an electronic time-domain reflectometer by electrical connecting means. Timed pulses are generated and impressed in the device by the instrument and reflections of the pulses are received by and are visually displayed on the reflectometer. The length of the device appears on the display as a straight line bounded by two inflections. The straight line is indicative of the thickness of the refractory. The device includes a metallic conductor coaxial with an outer metallic sheath and separated therefrom by a refractory having a desired dielectric constant. The device has a free end and a confined end. The confined end may be contained in a junction box provided with electrical connecting means. Electric insulating packing may be used in the junction box.

Method of determining coke level

Abstract: Instruments measure and periodically store coke vertical temperature profile data sets at multiple coke guide levels within expected level range. Computer detects highest level in each data set above a reference temperature and terminal plots coke level as a function thereof.

Cutting-torch holder

Abstract: Apparatus for automatically maintaining a cutting torch a predetermined distance from an uneven work surface having transverse and longitudinal irregularities includes a slide member which is adapted to move in a vertical direction in response to such irregularities and is pivotally attached to a support arm, roller means ride on and traverse the uneven work surface, the support arm is attached to the roller means and a cutter torch is fixed in a holder vertically, adjustably attached to the support arm.

Method and apparatus for measuring roll gap and alignment for continuous casters

Abstract: Strand-like apparatus for measuring roll position, i.e., roll gap and/or roll alignment, is moved through a caster between roll faces of a series of oppositely spaced pairs of conveyor rolls which define either a straight or curved strand travel path. Apparatus includes carrier means having resiliently deformable parallel sensing surfaces with an elastomeric core, and plural lateral and plural diagonal inductive distance measuring means pivotally linked to the sensing surfaces for generating roll gap and alignment signals. These signals are recorded. Single and multiple harness means attach single and multiple measuring apparatus to a powered starter bar at one or more lateral strand axes, thereby to make lateral roll position measurements during multiple or single passes, respectively.

Zinc-alloy coated ferrous product resistant to embrittlement

Abstract: ZINC-ALLOY COATED FERROUS PRODUCT RESISTANT TO EMBRITTLEMENT Abstract of the Disclosure This invention is directed to an improved zinc containing metallic coated ferrous product, particularly sheet and strip, which is resistant to intergranular penetration by zinc and embrittlement of the ferrous base. Use of such zinc containing metallic coated ferrous product in elevated-temperature service, such as found with certain appliances and automotive exhaust components, is enhanced by the coated products of this invention. The resistance to embrittlement of the zinc containing metallic coated ferrous base, when subjected to elevated service temperatures, is achieved by the use of a high-phosphorus containing steel base. For a plain carbon steel base, a phosphorus content of at least 0.020% by weight, preferably at least 0.030%, and more preferably at least 0.039% was found sufficient to render such zinc-alloy coated ferrous base resistant to embrittlement by zinc. By use of such high phosphorus ferrous base, for the reception of a zinc containing alloy coating, an improved metallic coated ferrous product has been found which resists intergranular penetration by zinc and embrittlement of the ferrous base. Such coated product has extended service life at temperatures above about 450°F (232°C) and when restored to room temperature possesses a high degree of ductility.

Fatigue and corrosion resistant flexible wire strand assembly

Abstract: The end of a wire strand adjacent to a hot metal or resin type end fitting is relubricated after application of the fitting to the strand by injecting lubricant through a thin tube extending between the wires of the strand in the hot metal or resin portion of the fitting from the surface of the hot metal or resin to the neck of the fitting.

The effect of tin on the toughness of some common steels

Abstract: The primary purpose of this investigation was to determine the effect of tin on the toughness of six common plate, structural, linepipe, and rail steels containing zero to 0.25 pct Sn. To put the changes in toughness into better perspective, the effect of tin on tensile properties was also noted. The effects of tin on Charpy transition temperatures and shelf energy are dependent on steel grade or a combination of grade and heat treatment; for example, an increase of 0.01 pct Sn increased the 20 J transition temperature by zero to 2.3°C. Contrary to the case for transition temperature, the effects of tin on tensile properties do not depend on steel grade or a combination of grade and heat treatment. The tensile effects in the present study were found to be consistent with those noted in previous literature cited in the paper. A mechanism to explain the effect of tin on toughness is considered.

The Enriched Element for Finite Element Analysis of Three-Dimensional Elastic Crack Problems

Abstract: An improved procedure for enriching three-dimensional isoparametric elements with the asymptotic crack front solution is described. Results from finite element calculations, involving these enriched elements, for the three-dimensional problems of a straight crack in plane strain and an axisymmetric penny-shaped crack which demonstrate the high degree of accuracy attainable are presented. Some finite-element solutions for through-crack and surface flaw problems are then reported showing the influence of a free surface on the variation of the stress intensity along the crack edge. Special treatments of the crack front-free surface stress intensity are implemented and the results discussed.

Solid-state video camera having a video signal processor

Abstract: The low resolution of state-of-the-art solid-state video cameras with quantized image arrays has limited their usefulness in high-accuracy dimension measurement systems. A video output signal processor with a simple computing element improves the apparent resolution of these cameras by a factor of 10 and more. This is enough to widen the range of measurement applications for these cameras.

Method for beneficiating coal ore

Abstract: A new heavy liquid parting medium comprising an emulsion of water and a substantially water immiscible heavy parting liquid for use in beneficiating ores by gravity separations such as sink-float processes. The specific gravity of the emulsion parting medium can be adjusted by proportioning the relative amounts of water and the substantially water immiscible heavy liquid. As-mined coal is beneficiated using a water-trichlorofluoromethane emulsion as the parting medium in a sink-float separation process.

Theoretical and practical considerations of sheet steel surface cleanliness

Abstract: Paint failure on cold-rolled sheet steel occurs by cathodic delamination of the paint film. Steel exposed at discontinuities in the paint coating becomes the anode of an electro-chemical corrosion cell, and adjacent areas under the paint become the cathode of that cell. Highly alkaline conditions are created under the paint, severely weakening the coating system bond at the pretreatment/steel interface. Nonuniformly distributed amorphous surface carbon contamination is primarily responsible for the variable paint performance observed. Adjusting mill practices in pickling, tandem rolling, and annealing resulted in improved steel surface cleanliness.

Bearing retaining and positioning means

Abstract: An arrangement for retaining and positioning a tapered journal sleeve or bearing on the tapered journal of a rolling mill roll utilizes a circumferential groove in the cylindrical end of the roll, in which groove a number of cylindrical rollers are placed. The rollers have a diameter which is greater than the depth of the groove. Thus the rollers project outwardly from the groove and act as a stop for an extractor sleeve. Hydraulic fluid is used to force the tapered journal sleeve onto or off of the tapered journal of the rolling mill roll.

Stable Growth of Surface Cracks

Abstract: This paper describes the results of a theoretical study of the stable growth of a part-through crack emanating from a free surface. A three-dimensional finite element program, incorporated with enriched elements at the crack border, is developed to determine the stresses or displacements, or both. Increments of crack growth are predicted by application of the strain energy density theory assuming that the crack profile coincides with the path of minimum strain energy density function, dW/dV. A preset value of (dW/dV) c is used to develop various crack profiles under stable growth while a critical strain energy density factor, S c =r c (dW/dV) c , is assumed to determine global instability that corresponds to the onset of rapid crack propagation.

Remote measurement of concentration of a gas specie by resonance absorption

Abstract: The concentration of a selected gas specie at a situs determined by directing a laser beam at the situs, the beam including a wavelength within the resonance absorption band of the gas specie, and measuring the intensity of the laser beam energy scattered from two spaced volumes along said beam at the situs. The ratio of measured intensities is a relative measure of the concentration of the gas specie at the situs.

Method for wiping hot dip metallic coatings

Abstract: The occurrence of defects on wire coated with an aluminum-zinc alloy coating applied by hot dipping in a molten coating bath is substantially decreased by preventing the deposition of zinc powder particles upon the surface of the molten aluminum-zinc coating prior to solidification of the coating. The deposition of metallic zinc powder particles upon the molten aluminum-zinc coating may be alleviated in several different manners, including preventing the formation of the zinc powder, preventing the accumulation of the zinc powder upon the surface of the molten aluminum-zinc bath, decomposing the zinc powder before it accumulates and exhausting or removing the zinc powder from the vicinity of the molten metal coated wire as it leaves the molten bath. Several novel apparatus arrangements for accomplishing the above are disclosed.

Method of heat treating a steel composition for chipper knife

Abstract: A ferrous alloy suitable for use as a knife in a rotary wood chipper, said alloy consisting essentially of, by weight, ______________________________________ Broad (%) Preferred (%)______________________________________Carbon .40-.60 .45-.50Manganese 1.0 max. .20-.40Phosphorus 0.035 max. 0.025 max.Sulfur 0.035 max. 0.025 max.Silicon 1.50 max. .30-.50Nickel 2.00 max. .25-.35Chromium 4.0-6.0 4.6-4.8Molybdenum 1.0-3.0 1.9-2.1Aluminum 0.10 max. 0.010-0.030Iron* balance balance______________________________________ *includes optional additions in nominal amounts of columbium, titanium, vanadium, tungsten, cobalt. The alloy, in a heat-treated condition, is characterized by (1) a high level of toughness on the order of 100 ft-lbs min. on unnotched specimens, (2) good wear resistance, (3) good machinability, (4) a hardness of at least 56 HRC after a double temper at 950° F. or higher, and (5) being hardenable using a maximum of 1850° F. as the austenitizing temperature.

Analysis of Sensor-Lance Samples for Basic Oxygen Furnace Control

Abstract: As part of a new basic oxygen furnace (BOF) steelmaking control system, procedures were developed for rapidly handling and accurately analyzing steel samples taken with a sensor-lance from an upright vessel. Determinations must be: (1) accurate to control the steelmaking process and assure that the heats are made to specifications, and (2) rapid to reduce BOF turnabout time and thus provide the potential to increase productivity. A pneumatic tube carrier was developed to safely transport hot (2200°F) lance samples to the laboratory. The samples are cut and cooled simultaneously on a high-speed abrasive cutoff machine equipped with a specially designed sample clamp and a high-volume water cooling system. Initially, the analytical performance was not as good as that obtained from conventional cast disk samples. Analysis deviations were traced to large slag-type sulfur-bearing inclusions in the lance samples. Accurate analyses were then obtained by increasing the spectrometer preburn time from 3 to 15 s. More than 1000 trial heats have been made. The procedures we developed permit hot samples to be removed from the lance sampler, sent to the laboratory, analyzed, and reported in about 3 minutes.

Method of making metal forming punches

Abstract: An inexpensive method to make a punch for piercing or forming metal includes cutting a piece from a bar or rod, applying a phosphate and lubricant coating to the piece, extruding one end of the piece into a polygonal shape, annealing the piece, press or machine relieving the piece, machining the end of the piece having the polygonal shape and heat treating the piece to the proper hardness.

Cooling naphthalene-bearing waters and gas streams

Abstract: COOLING NAPHTHALENE-BEARING WATERS AND GAS STREAMS Abstract of the Disclosure A method for cooling naphthalene containing gas streams using recirculated cooling water comprising physically separating suspended naphthalenic solids from the used cooling water, injecting a water immiscible solvent for naphthalene into the clarified cooling water, and vigorously mixing the solvent and cooling water to form a dispersion which is recooled in an indirect heat exchanger without serious buildup of naphthalenic solids in the heat exchanger and recycled to cool the gas stream

One side coating of continuous strand

Abstract: Improved method for the continuous coating of one side only of a metal strip with molten coating metal, more particularly, one side galvanizing of a ferrous metal strip. The method includes moving a metal strip, supported by a deflector roll having a width less than that of the strip, in an arcuate path through a bath of molten coating metal with the side of the strip to be uncoated contacting the deflector roll. To prevent coating of the strip, a stream of gas is directed toward the edges of the side of the strip contacting the roll which project beyond the roll and against the surface of the bath.