Патент USA US2111454код для вставки
Watented Mar. l5, ‘i938 I 2,111,454 HIGH STRENGTH CORROSION RESISTANT FERROUS ALLOY SHEETS Victor ll. Lawrence, Norristown, Pa; assignor to Alan Wood Steel Company, a corporation of Pennsylvania No Drawing. Original ‘application May 25, 1935, Serial No. 23,520. Divided and this applica tion May 15, 1937, Serial No. 142,828 3 Claims. (Cl. 148-31) This invention .relates to the production of other desirable physical properties, that are ob-' tainable by cold rolling and at the same time rolled iron and steel sheets and plates character either bene?cially affect, or at least not mate ized by relatively high resistance to rust and cor rosion, and having‘ high. tensile strength‘ and rially decrease, the corrosion resistance proper ductility as well as other physical properties that ties of the, alloy ascompared with those that would be exhibited by a similar alloy worked by make for ease of fabrication by methods involv the hot rolling process. ing welding, bending and similar operations. By the term "cold rolling” I mean a rolling As pointed out in my ‘co-pending application, Serial'No. 23,520, ?led May 25, 1935, of which this operation carried on with the slab, plate or other body of metal in‘ the cold state orat least at ,a in is a division, it has long been common practice to temperature below the lower‘ critical range at the cold roll iron and steel to obtain increased beginning of the rolling operation,‘ and in which strength. However, cold rolling hasthe disad vantage that it lowers the corrosion resistance of the metal is brought at least to the state of hard-' the metal. Therefore, cold rolling is not applied ness known commercially as “% hard cold rolled”. ' ' ' The comparison ofthe properties of such acold lid where it is desired that the ?nished sheet or plate rolled sheet is made with those of a sheet of sim shall have a high resistance to corrosion, and, ilar analysis thate has been hot rolled and an; .' consequently, it has not been practical to pro ' ‘I _ , , -, v duce cold rolled sheets and plates from special healed or normalized. The new product that I claim as my invention iron and steel alloys designed by reason of their may be produced by selecting a copper-contain-i' 20 composition to have ‘high corrosion resistance. ing iron or steel alloy, of the ferritic type'and bra , In other words, the sacri?ce of corrosion resist ance of these alloys has been such as to make it suitable composition to exhibit resistance to cor and at the same time readily rollable when unattractive from the commercial standpoint to rosion heated, and heating this alloy, in the form of a cold roll them to obtain high strength. There or billet of suitable thickness, to a temper 25 fore, where it is desired to produce sheets and slab ature ‘above or within the upper critical range plates having both high corrosion resistance and and then while accelerating the cooling of ‘ high strength, resort has been had to special iron the metal rolling by applying water ‘or any other cooling and steel alloys combining to a" greater or lesser medium, the combined rolling and cooling being extent the properties of high strength and cor until the metal has cooled or quenched 30. rosion resistance when the alloy is formed into continued to below the critical range. The rolling may be sheets or plates by hot rolling. ' continued after the temperature is below the crit- ‘ Steel sheets of high strength have been pro duced by the alloying of iron with hardening ical'range, in this way combining the effect. of rolling and quenching‘ and imparting to the elements—carbon, manganese, chromium, nickel, cold metal greater tensile and elastic strength with molybdenum, etc., but the fabrication by welding less of ductility to the piece than would re of such iron alloys has involved di?lculties which sult loss by either cold rolling or quenching“ applied have made them commerciallyiundesirable for uses requiring their welding, and the maximum individually. The rolling carried on after the - weldable limits of ferrous alloys hardened by metal is below the critical range does not appear 40’ to adversely a?ect the corrosion resistance prop 40. additions of. one of the above elements, or combi erties of the metal. ' nations of these elements, established by the pres I have found that the rolling operation is ad ent welding technique is too low to permit more vantageously carried out in a conventional three than ,moderate increases in strength. \ high rolling mill through which the pieces are Summarizing the above, sheets and light struc to and fro. A tilting table is provided atv 45 is tural shapes formed from iron or steel alloys com passed each side of the mill to catch the pieces as they bining higher resistance to corrosion, high strength, and good welding properties; have not are rolled and lift them into the return pass.‘ been available at a reasonable cost of production.‘ The starting material-billet, slab,‘ plate or I have found that by appropriate selection of break-down-is.brought at the appropriate tem '50 perature .from a furnace disposed conveniently = the iron or steel analysis with respect to work near the entering side of the mill. The rolls are ability and resistance to corrosion, and conduct kept cool by means of water sprays which elim ing the rolling operations in the manner herein after more particularly described, it is possible to inate change in shape of the rollskdue to heating produce sheets, platesand other relatively thin and at the same time promoting the cooling of" the structural shapes having the high strength and 7 pieces being passed through the rolls. The proc 2 2,111,454 ess can also be carried out on mills other than suitable relation is maintained between the rate of cooling of the material as it undergoes’ rolling ample, two-high or-four-high continuous mills, , and quenching and the rate of reduction to the providing the material is cooled and quenched desired thickness. In the case of heavier sheets, during the rolling operation by the application of say, %"--1%" in thickness, the slab should be Water or other cooling medium. heated to about 2000’ F., or well above the A03 The product may be produced from any one critical range. Starting with a slab of say of a wide range of copper-containing iron and 11/2”-3" thick, reduction to about %” may be steel alloys of the non-austenitic or ferritic type. expected at the time the temperature of the slab 10' One of the advantages of the present invention or plate has fallen to the Ac: point, or around resides in the fact that the product produced 1750° F. for a low carbon steel. The rolling and from relatively cheap iron and steel alloys will quenching should then be continued, the larger. meet strength and corrosion resistance speci? part of the further reduction occurring with the cations that heretofore could only be met by steel in the Aer-AC3 range. However, it is pref resort to more expensive iron and steel alloys. erable to so conduct the operation as to insure A group of relatively inexpensive corrosion re that. some further reduction must be effected sistant iron and steel alloys that are amenable after the temperature of the metal has fallen be to the process of my application Serial No. 23,520, low the A01 range. In this way it is insured that and can be formed into sheets and ‘plates having there will not be any annealing effect which 20 relatively high strength without detrimental would tend to nullify the results of the accelerat— 20 effect on their corrosion resistance, are those cop ed cooling and rolling treatment. At, the same per-containing iron and steel alloys in which the time, further improvement in the strength prop carbon content is kept under 0.50%, the copper erties of the sheet is brought about in this ?nal is under 0.80%, and phosphorus is less than stage under conditions opproaching those of cold 0.10%. I have found, ‘for example, that im rolling but without the detrimental effects on the 25 provement in strength values of the order noted corrosion resistance of the product that is char below may be obtained by rolling a copper-bear acteristic of cold rolling. ing steel of the following analysis range under When starting with pieces that have already the conditions of accelerated quenching herein been brought down to a relatively thin cross-sec~ 30' before described: tion by hot rolling, they may be brought to the 30 Percent combined quenching and rolling operation of the. C _______________________________ __ 0.1 —0.3 present invention at a temperature within the Mn _____________________________ __ 0.30 -0.70 A03 critical range. For example, starting with S _____ ___ ________________________ __ minus-0.04 steel sheets or break-downs that have been hot 35 P _______________________________ __ .06 -0.10 rolled to 1%" and which it is desired to reduce to 35 Cu _____________________________ __ 0.35 — .50 sheets of 1%" thickness, the temperature at the beginning of the combined quenching and roll ing operation may be about 1600° F. Elastic Ultimate limit strength While the invention has been described with lbs/sq. in lbs/sq. in. 40 particular reference to the production of sheets, 40 it will be understood that bene?cial results may Ordinary hot rolled _________________ __ 33, 000 55, 000-65, 000 be obtained in producing other products of thin Present process ______________________ __ 70, 000 90, 000 cross-section such as light plates and strips. In fact, any structural shape that may be formed by and, what is particularly important, these values rolling and having a cross-section of a similar are obtainable without adversely affecting the thinness as sheets and light plates is to be con 45 corrosion resistance of the alloy. sidered as within the scope of the invention. Ex When the product is intended to be fabricated cept where the context indicates a more restrict by welding, the proportion of carbon should be ed meaning, the term “sheet” as used in the speci kept below about 0.30%, and should be propor ?cation and appended claims is to be understood tionately lower if one or more other hardening as including plates and other structural shapes of 50 elements are present in the analysis. By the thin cross-section.’ term “hardening element” is meant any element The term “slab” as used in the speci?cation is which will cause the steel to become appreciably to be understood as including not only slabs as Cl 01 hardened by air quenching from around 2400° F., this term is applied in its more restricted sense in 55 i. e., temperatures adjacent to the welding tem the rolling industry but also billets, plates and perature zone. sheets which have been preliminarily worked by Except to the extent that such alloys are ex hot rolling from the original cast ingots, and cluded for uses requiring welding as above indi which are intended to be further reduced to bring 60 cated, the product may be produced fromv com them to ?nal dimension. 60 mercially available copper-containing irons and I claim: steels of the ferritic type that contain, besides 1. As an improved article of manufacture, a copper, greater or lesser amounts of one or more rolled sheet of a corrosion resistant ferrous-base of the elements chromium, manganese, molyb alloy of the ferritic type containing an effective denum, nickel, silicon, phosphorus and vanadium. amount but less than 0.8% copper, less than 0.5% 65 In carrying out the rolling operation the tem carbon, and less than 0.1% phosphorus, said sheet perature at which the slab or other partially re having the corrosion resistance properties of a duced shape is brought to the rolls will vary some hot rolled sheet of like analysis, and said rolled what depending on the thickness of the slab and 70 the thickness desired in the ?nished sheet or sheet being further characterized by the strength properties and a physical structure such as is pro plate. The thickness of the slab brought to the duced by heating said alloy to a temperature at 70 rolling operation should also be considered in least approximating the upper critical point, then relation to the temperature, the extent of the simultaneously subjecting the alloy to rolling and reduction required and the time involved in quenching and continuing said combined rolling 75 effecting the reduction, so as to insure that a and quenching treatment until the temperature 75 the conventional three-high rolling mill, for ex H ,iiintu of the rolled product has been brought below the - ' of the rolled product has been brought below the 2. As an improved article of manufacture par ticularly adapted to be fabricated by welding, a lower critical range. 3. As an improved article of manufacture,v a rolled sheet of a steel alloy of the ferritic type rous-base alloy of corrosion resistance analysis and of the ferritic type, containing hardening ele 0.04%, phosphorus ODS-0.1%, and copper 0.35 0.5%, said sheet having the corrosion resistance ments in an amount not exceedingsthe hardening equivalent of 0.3% carbon. said sheet having the corrosion resistance properties of a hot rolled sheet of like analysis, and said rolled sheet being by the strength properties and a physical 'struc lower critical range. . rolled sheet composed of a copper-containing fer- * containing carbon (Ll-0.3%, sulphur less than further characterized by the strength properties and a physical structure such as is produced by heating said alloy to a temperature at least ap proximating the upper critical point, then simul taneously subjecting v the alloy to rolling and quenching and continuing said combined rolling and quenching treatment until the temperature properties of a hot rolled sheet of like analysis, and said rolled sheet being further characterized ture such as is produced by heating said alloy to a temperature at least aproximating the upper critical point, then simultaneously subjecting the alloy to rolling and quenching and continuing said combined rolling and quenching treatment until 15 the temperature of the rolled product has been brought below the lower critical range. VICTOR H. LAWRENCE.