Showing papers by "Bethlehem Steel published in 1995"

A simple technique to generate in-plane forming limit curves and selected applications

Abstract: A simple technique to generate in-plane forming limit curves has been developed. This technique is based on the Marciniak biaxial stretch test using a single punch/die configuration, but the specimen and washer geometries have been modified in order to achieve failure in both drawing and stretching deformation modes. The experimental technique is described, and the advantages of using this inplane method over the conventional out-of-plane dome method are discussed. It is shown that (a) sheet thickness has an intrinsic influence on forming limits that is not related to small bending strain variations with thickness or to deformation in the presence of friction and curvature, (b) plastic anisotropy (\(\bar r\) value) does not substantially affect forming limits, and (c) in-plane forming limits are slightly lower (5 to 6 pct) than out-of-plane forming limits near plane strain; these differences are smaller than previously reported values (12 to 15 pct) in the literature.

Solubility products for titanium-, vanadium-, and niobium-carbide in ferrite

Abstract: Carbide- and nitride-forming elements, such as titanium, vanadium, and niobium, play important roles in the metallurgy of many modern steel products. These elements readily precipitate as stable carbides/nitrides during processing, even when present at relatively small levels. The precipitation of these alloy carbides/nitrides provides a means for controlling strength or hardness, grain size, the level of solute carbon, and other factors that affect properties and performance. Precipitation in austenite during hot deformation has received considerable attention and ''solubility products'' for many compounds have been published and used as alloy/processing development tools. The technologically important alloy nitrides generally exhibit relatively low austenite solubility. Alloy nitride solubilities in ferrite are even lower and, for practical purposes, can often be considered zero. In contrast, some alloy carbides exhibit substantial solubility in ferrite. However, thermochemical or solubility data on carbide/ferrite equilibria are sparse and, as a result, few experimental ferrite solubility relationships are available. A method is described herein for obtaining such a relationship from a known or assumed austenite solubility product using information on the activity coefficients of the solutes of interest. Solubility relationships for titanium-, vanadium-, and niobium-carbide in ferrite are then derived from published austenite solubility products and available thermodynamic informationmore » on binary Fe-Ti, Fe-V, and Fe-Nb solid-solutions.« less

Interfacial tensions of liquid Fe-Ni alloys and stainless steels in contact with CaO-SiO2″AI2O3-based slags at 1550 °C

Abstract: In the present work, the interfacial tensions of Fe-Ni alloys in contact with slags of the CaO-Al2O3-SiO2 system were measured at 1550 °C. Nickel additions to the alloy were found to decrease interfacial tension. The effects of alumina and titania additions to the slag on the interfacial tension of the Fe-20 wt pct Ni alloy were determined: alumina was found to increase the interfacial tension by a small amount, while titania was found to decrease it drastically. Using the present interfacial tension data for the CaO-Al2O3-SiO2 system and the ones measured by Jimbo and Cramb, Girifalco and Good’s interaction coefficient (ϕ) was determined as a function of the slag composition using regression analysis and was found to be a useful means of correlating interfacial tension data. The interfacial tension of an Fe-20 wt pct Ni-2.39 wt pct Al alloy in contact with a CaO-Al2O3-SiO2 slag was found to decrease drastically in the first 60 to 75 minutes of the experiment due to the dynamic effects of mass transfer. Slight lowering of interfacial tensions of industrial stainless steels due to sulfur transfer from liquid metal to slag was also observed. The equilibrium interfacial tensions of type 304 stainless steels were found to be more dependent on the slag chemistry than on the nickel and chromium content of the alloy.

Embossed cold rolled steel with improved corrosion resistance, paintability, and appearance

Abstract: An embossed cold rolled metal (e.g. steel) sheet for use in manufacturing appliances and method of making same wherein the surface attributes of the embossed sheet are optimized to improve corrosion resistance of the painted product, promote uniform paint coverage of the sheet surface, reduce paint consumption, enable repainting without loss of pattern crispness, and provide consistent and aesthetically pleasing appearance of the painted sheet. The embossed sheet has a plurality of plateaus and impressions defined therein in a manner such that the arithmetic average surface roughness (Ra) of the plateaus is from about 50 to 100 microinches, the maximum impression depths over a given area are from about 0.0025 to 0.0032 inches, the impression walls define maximum slopes of from about 8-17 degrees, and there are no sharp corners or ridges at the transition points between plateaus and impressions.

Apparatus for controlling molten metal flow in a tundish to enhance inclusion float out from a molten metal bath

Abstract: Flow control apparatus for enhancing inclusion float out in a continuous caster tundish comprising a dam positioned downstream from an impact pad and an energy source positioned between the dam and the exit nozzle of the tundish. The dam receives an incoming flood of molten metal released from the impact pad and redirects the flood of molten metal into multiple sub-flow currents which carry entrained inclusions toward a slag cover on the surface of the molten metal bath to enhance inclusion float out. The energy source provides means to restore kinetic energy to the sub-flow currents and increase the number of passes below the slag cover, thereby further enhancing inclusion float out.

Magnetic shaping of columns of liquid sodium

Abstract: The meniscus of a cylindrical column of liquid sodium in mineral oil was shaped under an electromagnetic field. The electromagnetic field was generated by an alternating current flowing through a coil surrounding the liquid metal column. The equilibrium shape of the meniscus, under the influence of electromagnetic field, was experimentally measured and compared with the predicted results from the mathematical model. The experimental technique used to measure the meniscus shape of the liquid metal column and the development of the mathematical model are presented. The validity of the mathematical model to predict the meniscus shapes is also discussed.

Ferrocyanide-free halogen tin plating process and bath

Abstract: Incorporating an additive into a tin electroplating bath substantially inhibits soluble ferrous ions, ferric ions, and stannous ions from reacting thus minimizing the formation of stannic tin which is lost in the plating sludge.

The influence of laser surface melting on the resistance of AISI 4135 low alloy steel to hydrogen-induced brittle fracture

Abstract: Flat and cylindrical heat-treated AISI 4135 low alloy steel specimens were surface treated using power levels of 50, 100 and 200 W. The results of hydrogen permeation and slow strain rate tension (SSRT) tests show the following. 1. (1) Laser surface treatment of AISI 4135 low alloy steel results in a reduction in the hydrogen absorption kinetics as measured by the permeation test, and also an improved resistance to hydrogen-induced fracture in the SSRT test under galvanostatic charging conditions. 2. (2) The degree of effectiveness in reducing the hydrogen absorption rate is shown to occur at all power levels, and is greatest at the 50 W level. 3. (3) A clear qualitative relationship is described between the hydrogen absorption rate and the time to failure in the SSRT test. This relation was even more striking in terms of the fractographic detail of the fracture face. 4. (4) A possible explanation for the reduced hydrogen absorption as a result of low power laser surface melting treatment is the influence of the rapidly quenched metal surface on the steady state degree of hydrogen adatom coverage or the absorption kinetic rate constant or both. 5. (5) Reverse membrane permeation experiments indicated that the effect of laser surface melting on the permeation flux at constant charging current was not due to barriers in the metal which alter the hydrogen flux gradient across the membrane.

Apparatus and method for vacuum treating molten steel

Abstract: An apparatus for vacuum treating molten steel includes a ladle having a sidewall, a substantially circular closed bottom, and an open top. A first gas injector is operably associated with the bottom for introducing a supply of a selected first gas into the ladle. A barrel degasser is operably associated with the ladle for being introduced into the ladle through the open top. The degasser includes a generally cylindrical shell having a single substantially continuous diameter opening them through defining a treatment space. A second gas injector is radially directed and operably associated with the shell for communicating with the treatment space. A source of the first gas is in flow communication with the first and second injectors. A vacuum source is operably associated with the barrel degasser for applying a vacuum to the treatment space.

Method of preparing titanium-bearing low-cost structural steel

Abstract: A fully killed steel has a composition that is tailored to meet a 50 KSI minimum yield strength after hot rolling and accelerated cooling. The steel has a carbon content in the range of from about 0.05 to about 0.10 percent or from about 0.15 to about 0.27 percent, from about 0.005 to about 0.020 percent titanium, from about 0.004 to about 0.015 percent nitrogen, from 0 to about 0.02 percent vanadium, and the remainder iron plus incidental impurities. The steel is continuously cast, hot rolled to plate, and cooled to a temperature of less than about 1100° F. at a cooling rate lying in a cooling rate band extending from about 2° to about 14° F./sec at 2 inches plate thickness, from about 7° to about 26° F./sec at 1 inch plate thickness, and from about 13° to about 45° F./sec at 1/2 inch plate thickness.

Effects of silicon and nickel contents on the atmospheric corrosion resistance of ASTM A588 weathering steel

Abstract: Nine ASTM A588 low-alloy weathering steels representing three levels of silicon and nickel were prepared by induction melting and hot rolling in the laboratory. Corrosion tests were conducted for eleven years at four atmospheric sites which included industrial, rural, and marine locations. The results were fitted to kinetic equations of the form, C= At B , where C is the corrosion loss, t is time, and A and B are constants in accord with Method 1 of ASTM G101 'Standard Guide for Estimating the Atmospheric Corrosion Resistance of Low Alloy Steels." Both silicon and nickel are shown to have a beneficial effect on the corrosion resistance of A588 weathering steel. For silicon, on average, each 0.1% increase results in a 4% decrease in corrosion loss after 11 years, a 6% decrease in corrosion rate after 11 years, and a 12% increase in the time to reach a 10-mil(250pm) penetration. For nickel, each 0.1% increase results in a 4% decrease in corrosion loss after 11 years, a 7% decrease in corrosion rate after 11 years, and a 15% increase in the time to reach a 10-mil(250μm) penetration. By way of comparison, Method 2 of ASTM G101 predicts a 2% increase in the corrosion index for each 0.1% increase in silicon or nickel.

Method for producing flanged structural products directly from slabs

Abstract: Flanged structural products are rolled directly from rectangular slabs using only a universal mill having web rolls of fixed width corresponding to a selected finished web depth of the finished product. Original slab width is dependent upon the area ratio of the web and flanges in the intended finished product. Flanged structural products are rolled directly from rectangular slabs using only a universal mill having web rolls of fixed width corresponding to a selected finished web depth of the finished product. Original slab width is dependent upon the area ratio of the web and flanges in the intended finished product. As the slab thickness is reduced between web rolls, flange rolls simultaneously apply pressure to the longitudinal edge surfaces of the slab, moving material toward the slab's center. The edge surfaces of the slab become upset in each pass so that the slab thickness at the edges exceeds the original slab thickness. As rolling proceeds, the web rolls are brought closer together as are the flange rolls. At every set point of these rolls, the cross section of the now deformed slab maintains a fixed ratio of areas between the web and the flanges, the same area ratio as in the finished product. The web and flange rolls are moved in precalculated increments until the slab takes on a finished wide flange shape, ready for use in the construction industry.

Development and application of an integrated neural system for a HDCL

Abstract: This study presents the development and application of an integrated neural system in coating weight prediction and adaptive control for a modem hot dip coating line (HDCL). The neural system consists of two multilayer feedforward networks (with backpropagation learning) and a neural adaptive controller (with adaptive learning). They perform coating weight prediction, feedforward control and adaptive feedback control respectively. The production environment analysis and the design of the neural system architecture, associative memory, generalization and stability are addressed in detail. The real-time industrial application results are also given to show the benefits through applying an integrated neural control system in a modem hot dip coating line.

Bake hardenable vanadium containing steel

Abstract: Rolled articles such as hot rolled or cold rolled and annealed sheet and/or strip include effective amounts of vanadium in low carbon steels to produce an improved bake hardenable product especially adapted for automotive use. The use of vanadium in the alloy steel chemistry controls bake hardenability, permits solution annealing at lower temperatures in its manufacturing sequence and specifies a composition range which is more easily cast within desired limits and causes less variation in final mechanical properties. The steel has a composition consisting in weight percent of between 0.0005 and 0.1 % carbon, between zero and less than 0.04 % nitrogen, between zero and less than 0.5 % of a nitride forming element, between zero and 0.5 % aluminium, between zero and up to 2.5 % manganese, between 0.005 and 0.6 % vanadium with the balance iron and inevitable impurities.

Levitation of liquid sodium droplets

Abstract: Droplets of liquid sodium ranging from 1.2 to 2.1 g, immersed in mineral oil, were levitated in an electromagnetic field. The experimental setup was designed and constructed to levitate small metal droplets at audio frequencies. The levitated droplet was found to be very stable inside the inductor, and the equilibrium shape attained by the droplet in the electromagnetic field was measured during the experiment. A surface coupled mathematical model was used to calculate the self-consistent equilibrium droplet shape of liquid sodium under the influence of an electromagnetic field. The predicted shapes of the metal droplet and the position of the droplet inside the inductor compare well with the experimental data.

Laser Surface Alloying with Noble Metals to Impede Hydrogen Ingress Into AISI 4135 Steel.

Abstract: Fe-Pd, Fe-Pt and Fe-Au surface alloys were produced using a technique consisting of electrodeposition of the respective noble metal on quenched and tempered AISI 4135 steel followed by laser surface melting using a CO 2 laser at three power levels. Auger electron spectroscopic depth profiling was carried out to determine the degree to which alloying was achieved. Hydrogen permeation testing carried out on the surface-alloyed specimens showed reduced hydrogen absorption compared with the untreated and the surface-melted-only conditions, with the Pt-alloyed specimens showing the greatest reduction. Attempts made to determine the effect of the laser surface treatment on the hydrogen surface coverage as well as the other parameters of the hydrogen evolution reaction using the I-P-Z model were inconclusive, since several parameters were found to be simultaneously affected by the surface treatment.