US3196052A - Prestressing wire and method of manufacturing the same - Google Patents

Prestressing wire and method of manufacturing the same Download PDF

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US3196052A
US3196052A US120441A US12044161A US3196052A US 3196052 A US3196052 A US 3196052A US 120441 A US120441 A US 120441A US 12044161 A US12044161 A US 12044161A US 3196052 A US3196052 A US 3196052A
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Prior art keywords
wire
tensile
stress
tension
temperature
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Hann Kenneth Graeme
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Somerset Wire Co Ltd
Allied Steel and Wire Ltd
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Somerset Wire Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21F—WORKING OR PROCESSING OF METAL WIRE
    • B21F99/00—Subject matter not provided for in other groups of this subclass
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C9/00—Cooling, heating or lubricating drawing material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D3/00—Straightening or restoring form of metal rods, metal tubes, metal profiles, or specific articles made therefrom, whether or not in combination with sheet metal parts
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/08—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement

Definitions

  • This invention relates to a new or improved method of straightening metal wire.
  • the present invention is concerned with the straightening of cold drawn high tensile steel wire which is formed of plain medium carbon and high carbon steel as opposed both to alloy steel, and also to mild steel, the tensile strength of which latter steel is too low for it to be useful for the purposes herein described.
  • the invention is concerned in particular with medium and high carbon steel wire having a carbon content within the range of 0.35% to 0.9%.
  • medium and high carbon steels manganese and silicon are present by reason of having been added as deoxidising agents in accordance with ordinary steel manufacturing practice, the manganese content usually not exceeding 0.7% and rarely, if ever, exceeding 1.0% and the silicon content usually not exceeding 0.4% and rarely, if ever, exceeding 0.8%, the sulphur and phosphorous contents of which usually do not exceed 0.04% and 0.03% respectively, and the maximum permissible upper limit of these two latter elements being in general 0.06% in each case; with iron and the usual residual, i.e., commercial impurities forming the balance of the composition.
  • Medium and high carbon steel having a composition as described in this paragraph, in particular a carbon content within the above range of 0.35% to 0.9% is herein referred to as plain carbon steel.
  • a further specific and very important application of the invention is in the production of pre-stressing wire for reinforced concrete construction wherein it is of especial importance that the wire should not only be of a markedly straight configuration but should also possess particularly good tensile properties including a high ultimate tensile stress and the maximum resistance to creep under a continued tensile loading. That is to say in such application to pre-stressing wire, it is most important that the wire should possess a low stress relaxation, that is to say, the minimum of reduction or falling off of its tensile stress from some initial maximum, during the continued tensile loading of a piece of wire, the length of which is kept constant. In other words, the strain in the wire therein is maintained at a constant value of progressively reducing the tensile loading, i.e., the tensile stress in the wire and over an extended period of time.
  • such stress relaxation characteristic is a measure of the, usefulness of the wire as a pro-stressing wire.
  • This wire of diameter 0.2" was advanced in the cold state through a rotary straightening machine as aforesaid, and I found a reduction in the 0.1% proof stress of between 10 and 15% and a reduction in the ultimate strength of the wire by substantially 5%.
  • a principal object of the present invention is the provision of a new or improved method of straightening cold drawn plain carbon steel wire, which method avoids the aforesaid impairment of certain of the mechanical properties of the wire as occurs if the wire is straightened in the cold state by the existing technique above referred to, which method in accordance with this invention serves incidentally to improve substantially certain of the mechanical properties of the wire, namely in particular to improve substantially its creep resisting properties un der tension as well as to increase the elongation of the wire before failure under tension.
  • a further object of the present invention is to provide an improved method of manufacture of a plain carbon steel pro-stressing wire by which the wire is characterized by a particularly low stress relaxation.
  • a further object of the present invention is to provide a new or improved method of manufacturing a plain carbon steel pro-stressing wire which is characterized by having a particularly high ultimate tensile strength.
  • the present invention in its essentials comprises a method of straightening a cold drawn plain carbon steel wire and having a carbon content within the aforementioned range of 0.35% to 0.9%, and preferably within the range of 0.4% to 0.8%, wherein the wire after the cold drawing operation is heated to a tempering temperature within the range of 150 C. to 500 C., and preferably within the range of 200 C. to 400 C., and a controlled tension is applied to successive lengths of the so heated wire, such tension being of magnitude sufiicient to effect a permanent elongation and straightening of the wire without subjecting the wire to such a high tensile stress as to cause it to fracture.
  • the foregoing method in addition to producing a straightening effect on the wire, also results in relieving local stresses by the subjection of the wire to a tempering operation, and improves significantly the tensile properties of the wire, notably by increasing its ultimate tensile stress and improving its creep resistance and stress relaxation under continued tensile loading.
  • DEFINITIONS H (1) By the expression permanent elongation employed herein is meant that the elongation imparted to the wire when heated to a tempering temperature as defined below is at least partially retained after the wire has cooled to normal, i.e., room temperature.
  • the elongation of a given length of wire which is produced is greater than that expected from the sum of the strain in the wire due to the applied tensile load and the linear expansion due to the rise in temperature.
  • tempering temperature is meant a tempering temperature as customarily understood in the art of heat treating the plain carbon steel to which the invention is applied, that is to say it is a temperature within the tempering range to which the steel would be heated after a quenching operation for the purpose of increasing its ductility.
  • tempering temperature will necessarily, of course, be below the lowest transformation point in the iron carbon diagram and will necessarily vary in accordance with the analysis of the particular steel concerned.
  • tempering temperature would, as is well understood, be within the range of 150 C. to 500 C., and as hereinafter explained would preferably be within the range of 200 C. to 400 C.
  • straightening as used herein is meant that the shape of the wire which is subjected to the straightening operation is made to conform more closely to an absolutely straight configuration, but such expression is not herein intended necessarily to imply that'the wire is so shaped by the method according to this invention as to be perfectly straight, although it is believed that in fact by the method according to this invention it is possible to produce wire. in a form which closely approximates to that of absolute straightness.
  • the invention is capable of a general application of which one very important application is in the production of wires for use in the manufacture of wire spokes
  • the invention is especially applicable to the production of wires for use in pre-stressed concrete as not only does the particularly straight configuration of the wire facilitate its use for this purpose, but as hereinbefore explained under paragraphs (b) to (d) inclusive above, the improvement in the tensile properties make it especially suitable for this work.
  • pre-stressing members wire formed of plain carbon steel as herein defined, and produced by ordinary cold drawing operations, and these entail the disadvantage that when they are subjected to a tensile load equal to half or more than half of the breaking load, the elongation of the wire increases with time and concurrently the stress in the wire held at a constant strain relaxes with time.
  • the present invention is essentially concerned with a method of straightening cold drawn wire formed of plain carbon steel, and although the method may be applied to such wire which has previously been subjected to a cold drawing operation, the cold drawing operation and the straightening method in accordance with the present invention are preferably combined, so that the drawing down die or the reducing rolls employed in the cold drawing operation may co-act with the wire pulling means employed in producing the required tension, such pulling means comprising various known forms of gripping devices, for example caterpillar gripping jaws, or a power driven rotating block or capstan, around which the wire would be wound continuously after its straightening.
  • the preferred method of heating the wire or the like is by direct resistance heating, i.e., by passing an electric current through that part of the wire or the like which is being subjected to the tensile loading, but other methods of heating may be used such as induction heating, or by passing the Wire through the lead orsalt bath, or through some form of furnace.
  • the invention may be applied to wire or the like of plain configuration, or it may be applied to wire which is of indented configuration peripherally, and the indenting operation may be combined with the straightenin method the subject of this invention.
  • the invention is applicable to plain, medium and high carbon steels as distinct from alloy steels and comprising a carbon content within the range of 0.35% to.0.-9%.
  • the minimum'valuepf this range is determined by the fact that with a carbon content below 0.35% the ultimate tensile strength of the steel is too low for the steel to be commercially useful in the production of wire required to possess marked tensile strength, as in the case, for example, of pre-stressing wire, and for the foregoingreason 0.4% carbon represents the minimum useful carbon content for many applications of plain carbon steel wire.
  • the upper limit of 0.9% for the carbon range is determined by the fact that 0.8% carbon is the eutectoid composition for iron carbon, and carbon in amount greater than 0.8% tends during the production of the wire to form at the grain boundaries pre-eutectoid cementite which reduces the ductility of the metal and makes the drawing operation more difficult. For this reason 0.8% carbon is the preferred upper limit for the carbon range.
  • FIGURE 1 shows a schematic layout of one form of plant for carrying out one specific method in accordance with the present invention
  • FIGURES 2, 3 and 4 illustrate modifications of the plant depicted in FIGURE 1 for carrying out respectively three modified forms of the said method
  • FIGURE 5 shows a graph illustrating the improvement in certain physical properties obtained in the finished wire when subjected to the straightening method forming the subject of this invention
  • FIGURES 6, 7, 8 and 9 are graphs depicting the relaxation characteristics of pro-stressing wires of a number of different analyses, and which wires have been subjected to the method of this invention.
  • the invention is here depicted as applied to the straightening of plain carbon steel wire so as also to improve the tensile properties thereof and to render the wire particularly useful for pre-stressed concrete construction.
  • the wire is first advanced in the cold state through one or more drawing down or reducing dies, one only of which dies of conventional form is indicated at 10 in the drawing, such die or dies serving to effect reduction in the cross section of the wire and thereby effectively to grip it.
  • the wire is advanced continuously through this die 10 by means of a continuously rotating power-driven capstan or block 11, around which the wire is coiled by the continued rotation of the capstan or blocked in the known manner.
  • This capstan or block 11 is generally of conventional form but has a diameter which is substantially larger than that normally used, a particularly convenient diameter to be employed being 350 to 500 times the wire diameter, i.e., a diameter of 100" in the case of wire of 0.2 diameter, which 100" diameter is substantially four times larger than that normally used.
  • the length of the wire advancing continuously from the drawing die to the capstan or block is depicted at 12.
  • the drawing die 10 is connected through lead 13 to one side of a motor generator of known form indicated diagrammatically at 12 and adapted to supply alternating or direct current at a low voltage, conveniently 20 to 40 volts, and at a substantial amperage, for example, of the order of 200 to 500 amperes.
  • a motor generator of known form indicated diagrammatically at 12 and adapted to supply alternating or direct current at a low voltage, conveniently 20 to 40 volts, and at a substantial amperage, for example, of the order of 200 to 500 amperes.
  • this motor generator is connected by lead 15 to a plurality of spring loaded current collecting brushes 16 which are in electric conducting engagement with the wire 12 at a position intermediate the drawing die 10 and the capstan or block 11, these brushes being so arranged as to permit of the wire advancing freely in relation thereto as it is coiled around the capstan or block.
  • the arrangement is such that a heavy current of the value above indicated is thereby passed along that part of the wire 12 which is between the brushes 16 and the drawing die 10.
  • the side of the motor generator 14 which is connected to the drawing die 13 is further connected by another lead 17 through adjustable resistance 10 and brush gear 19 to the rotating capstan or block 11 so as thereby to pass current along that part of the wire 12 which is between the capstan or block 11 and the brushes 16.
  • the adjustable resistance 18 is adjusted so as to maintain the wire 12 as it advances from the brushes 16 towards the capstan or block 11 at a substantially constant temperature, and a convenient current to pass along the wire between the brushes 16 and the capstan or block 11 for this purpose is one of the order of 50 to amperes, i.e., of magnitude substantially less than that passed along that part of the wire which is between the drawing die 10 and the brushes 16.
  • the arrangement is in fact such that a heavier current is passed along that part of the wire which is advancing from the drawing die to the brushes so as to raise this part of the wire relatively rapidly to the desired temperature, and the wire is subsequently maintained at such temperature for a predetermined period of time by the passage of the lesser current therealong between the brushes 16 and the capstan or block 11.
  • the maximum temperature to which the wire is heated is in fact a tempering temperature, namely, a temperature within the range of to 500 C., the preferred value of this temperature within the foregoing range being dependent upon a number of different factors as follows:
  • composition in particular the carbon content of the plain carbon steel employed.
  • the wire is heated to a maximum temperature which is within the range of 150 to 500 C., and preferably within the range of between 200 to 220 C. as the lower limit, and 400 C. as the upper limit, one especially preferred temperature range where the carbon content is approximately 0.8% being 350 to 400 C.
  • the definedlimits of 150 C. and 500 C; are determined as follows.
  • the lower temperature limit is determined by that fact that:
  • (ii) 150 C. represents the lowest practical temperature limit at any rate with the higher carbon contents, e.g., 0.7 to 0.9% at which the wire under commercial conditions of operation can be stretched without fracture, to produce a useful permanent elongation, i.e-., of at least 1%.
  • the defined limit of 500 C. represents the maximum temperature at which the stretching of the wire can be eifected consistent with the retention of a sufficiently high ultimate tensile strength for the process to be useful.
  • Such means comprise a tube 20 through the interior of which the wire passes, the tube having a bore substantially greater than the diameter of the wire and the end of the tube nearest to the capstan or block being partially closed 'so as to provide therein merely a central hole 21 of bore slightly greater thanthe diameter of the wire so as to provide a guide for the wire and maintain it substantially central within the tube.
  • the tensile load is applied to the wire by the action of the power driven capstan or block 11 in advancing the wire through the drawing die and the reduction in cross section at the drawing die must be sufliciently great as to enable this to exert the necessary grip on the wire for this purpose, so that the capstan or block may exert on the wirea tensile force sufficiently great as to produce the elongation in the length of the wire heated to the temperature aforesaidwhich is greater than the sum of the strain in the wire due merely to the tensile load and the linear expansion due to the rise in temperature. Otherwise the desired straightening of the wire would not be effected, and concurrently the above referred to improved creep resisting and elongation characteristics of the wire under tension would not be obtained.
  • tensile loading which is applied to the wire may be within the range of approximately 35% to 70% of the breaking load, and preferably is between 35% to of the breaking load, i.e., with a carbon steel .wire having a carbon content of 0.76% and a breaking load of approximately 100 tons per square inch the tensile loading applied may correspond to' a tensile stress in the wire of approximately 50 tons per square inch.
  • the invention as shown in FIGURE 2 may be similarly applied to wire which has previously been drawn down by taking a length of such drawn down wire, winding it around a feeding drum 24 provided with a brake or other means for retarding its rotation, the wire being fed from this feeding drum 24 to thepower driven capstan or block 11 and subjected in so doing to heating, tension, and cooling by means arranged in exactly the same way as in the case of the plant depicted in FIG- URE 1, as will be apparent from this FIGURE 2 of.
  • FIGURE 3 may advantageously be applied to wire which is not galvanised in that this arrangement is a simpler one than that of FIGURE 1 by its omission of the brushes 16.
  • the invention may also be applied to indented wire which, after the conclusion of the drawing down operation, is indented in the known manner by passing it, as shown in FIGURE 4, between a pair of indenting rolls 25 of known form provided in the usual way with a series of peripheral indentations or recesses.
  • indented wire is advantageous as applied to pre-stressed concrete.
  • I drawing down die 10 is replaced by one or more sets of reducing rolls indicated diagrammatically at 26, which serves to elIect equal reduction of the wire, and these reducing rolls may replace the drawing down die 10 with the arrangements depicted in FIGURES 1 and 3.
  • a transformer for supplying low voltage alternating current at the desired current density.
  • pro-stressing wire formed of cold drawn plain carbon steel and processed i.e., subjected to the method of this invention, using the particular plant depicted diagrammatically in FIGURE 3 of the accompanying drawings, are as follows:
  • Examplel l Example H i Example III 0. 70 O. 40 0. 51 0. 23 0. 061 0. 203 0. 021 0. 037 0. D45 0. D24 0. 028 O. 029 Manganese. 0. 63 0. 69 0. 61 Iron and re dual impurities t) 1 The remainder.
  • Comparative tensile tests were performed on wire in accordance with each of the three examples, these comparative tests being performed in the case of each of the three examples on wire subjected to the method the subject of this invention, under the conditions specified in Table A, and hereinafter referred to as processed wire, together with otherwise identical wire, i.e., of the same analysis manufactured under the same conditions and cold drawn to the same final diameter of 0.202"; such latter wire in each case being not, however, subjected to heating under tension in accordance with the present invention.
  • Such latter wire for convenience in description is herein referred to as unprocessed wire.
  • Example I the improvement of the tensile properties obtained with the processed wire as compared with the unprocessed wire, is further illustrated by the graph depicted in FIGURE 5 of the accompanying drawings, wherein is depicted two stress-strain curves for wire of the foregoing specific composition cold drawn down in each case by the final drawing down die to a diameter of .202, wherein the dashed line depicts the stressstrain curve obtained with the wire after drawing down before processing, and the continuous line depicts the stress-strain curve of this same wire after both drawing down and processing in accordance with the foregoing specific example.
  • test length of 29 was taken in each case and the test specimen was subjected to tension in a known form of creep testing machine embodying a heating furnace surrounding the wire so that the test could be carried out at both room and elevated temperatures, the latter being checked continuously by three thermocouples spread over the gauge length of the specimen.
  • the metal of the wire was stressed to a value of between 50% and of the ultimate tensile strength of the wire at room temperature, and after loading the Wire to the determined percentage within the above range of the ultimate tensile strength, the extension of the wire under the tensile loading was noted and was thereafter kept constant by periodically removing a portion of the tensile load applied to the wire, namely, by removing Weights from the beam of the tensile testing machine.
  • the stress relaxation tests are a measure of the behaviour of the wire under service conditions, i.e., as a pro-stressing wire in concrete constructions, and the reduction in the tensile stress both at room and elevated temperature is a measure of the ability of the wire to maintain its desired pro-stressing characteristics, i.e., its initial tensile loading both at room temperature and also when subjected to moderate heat as may occur during the initial stages of a building fire.
  • the usefulness of the wire as a pre-stressing wire is denoted by the percentage of the stress reduction or stress relaxation over a given period of time from the initial value; the smaller the reduction the greater the utility of the wire.
  • both the processed and unprocessed lengths of wire in the case of Example I, having the higher carbon content, namely, .76%, were loaded to an initial loading of 80 tons per square inch.
  • This initial loading was found too great in the case of the tests which were performed with Example I at elevated temperatures, and lower initial loading values were employed corresponding to the limit of proportionality in the tensile test, the initial loading selected for each elevated temperature being the same in the case of the unprocessed wire as well as for the processed wire at the particular temperature involved.
  • the initial loading of the wire was again of a lesser degree than that employed in Example I at'room temperature, the initial loading being 60 tons per square inch in the case of Example II and 66 tons per square inch in the case of Example III.
  • the stress relaxation for both the processed and unprocessed wire in each of the three examples at the end of 1000 hours for both room temperature and also for the particular elevated temperature tests above referred to is set out in the following Table C, in which table is set out both the initial stress to which the wire was subjected, and alsothe final stress at the end of 1000 hours while maintaining the length of wire constant. In the table is also set out the percentage reduction in stress necessary to maintain the constant length of the test specimen during the test, which percentage reduction stress is herein referred to by the term percentage stress relaxation. In this Table C, the abbreviation R.T., is used to indicate room temperature.
  • a further series of tensile tests and stress relaxation or creep resistance tests were carried out on a number of lengths of wire processed in accordance with the invention, in which the lengths of wire, following the cold drawing thereof, were stretched by differing amounts at various temperatures including a number of temperatures selected within the range of to 500 C.
  • the so processed wire was subjected to tensile tests in which measurements were taken of the ultimate tensile stress and the 0.1% proof stress.
  • the ratio of SF to S0 in each of the stress relaxation tests i.e. creep tests, was evaluated as providing an indication of the reduction in tensile stress necessary to maintain the length of the specimen unchanged under the tensile loading.
  • An extended stress relaxation test was performed with a length of wire according to Example I, i.e., with a carbon content of 0.76%, and stretched at a temperature of 200 C. so as to produce a permanent elongation, i.e., stretch of 2% at that temperature.
  • Two specimens which were respectively so processed were taken and initially loaded to a tensile stress of 100 and 110 tons per square inch at room temperature and subjected to stress relaxation tests at this room temperature, which was actually C., in a manner similar to the tests already described. The result of this further series of tests is set out in the graph forming FIGURE 9.
  • the tensile stress in the more highly stressed specimen fell at a more rapid rate during the first few hours than the specimen stressed to the lesser initial value and took considerably longer to reach a zero relaxation rate. Nevertheless the more highly stressed specimen attained a zero relaxation rate corresponding to total cessation of further creep under a stress in excess of 100 tons at the expiration of less than 8000 hours, while the specimen stressed initially to the lesser value attained zero relaxation at a tensile load of no less than about 93 tons per square inch after the expiration of a little more than 6000 hours.
  • a method of increasing the resistance to creep under tension of Wire for use in reinforced concrete construction comprising subjecting plain carbon steel wire having a carbon content within the range of to .9% to a cold drawing operation by advancing the same through drawing means, applying tension to the drawn wire to effect its advancement through the drawing means,
  • a method of increasing the resistance to creep under tension of plain carbon steel wire as herein defined for use in reinforced concrete construction comprising heating cold drawn plain carbon steel wire having a carbon content within the range of 0.35% to 0.9% to a temperature within the range of to 400 C., while simultaneously applying a controlled tension to the heated wire, and producing in the wire a permanent elongation of between 1% and 2%.
  • a method of increasing the resistance to creep under tension of plain carbon steel wire as herein defined for use in reinforced concrete construction comprising heating cold drawu plain carbon steel wire having a carbon content within the range of 0.4% to 0.9% to a temperature within the range of 200 to 400 C., while simultaneously applying a controlled tension to the heated wire so as to produce in the wire a permanent elongation of between 2% and 5%.
  • a method of increasing the resistance to creep under tension of plain carbon steel wire as herein defined for use in reinforced concrete construction comprising subjecting plain carbon steel wire having a carbon content within the range of 0.7% to 0.8% to a cold drawing operation by advancing the same through drawing means, applying tension to the drawn wire to effect its advancement through the drawing means and While sub jected to said drawing tension heating said wire to a temperature within the range of 350 to 400 C., and maintaining the drawing tension at such value as having regard to the time during which each wire length is maintained at the drawing temperature and the value thereof as to impart a permanent elongation to the wire and in 15 crease the creep resistance thereof without at the same time applying a tensile force sufficiently great to the wire as to efiect failure of the Wire under the applied tensile load.
  • a method of increasing the resistance to creep under tension of plain carbon steel Wire as herein defined for use in reinforced concrete construction comprising subjecting plain carbon steel wire having a carbon content within the range of 0.4% to 0.8% to a cold drawing operation by advancing the same through drawing means, applying tension to the drawn wire by means of a power rotated capstan or block around which the wire is coiled to effect its advancement through the drawing means, heating the wire after its emergence from the drawing means and while subjected to said drawing tension to a temperature within the range of 250 to 400 C., and maintaining the drawing tension at such value as having regard to the time during which each wire length is maintained at the drawing temperature and the value thereof as to impart a permanent elongation to the wire and increase the creep resistance thereof without at the same time applying a tensile force sufficiently great to the wire as to effect failure of the wire under the applied tensile load, and cooling the wire after it has been heated to the tempering temperature and before it is coiled around the capstan or block for the purpose specified.
  • a method of increasing the resistance to creep under tension of carbon steel wire as herein defined for use in reinforced concrete construction comprising subjecting plain carbon steel wire having a carbon con-- tent within the range of 0.7% to 0.8% to a cold drawing operation by advancing the.
  • a flexible tension member suitable for use in prestressed concrete structures which comprises cold drawn plain carbon steel wire. having a carbon content within the range of 0.4% to 0.9% and having its relaxation properties improved by heating the member subsequent to the cold drawing and under sufiicient tension to impart without rupture a permanent elongation of not more than about 5% to the member, to a temperature within the range of 150 to 500 C. such that the member is characterized by having a tensile strength of from to more than long tons per square inch, depending upon the carbon content and the temperature of heating, and a stress relaxation of less than 3% when subjected at room temperature to aninitial load of at least 70% of its tensile strength and thereafter maintained at a constant length for 1000 hours.

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US120441A 1953-06-01 1961-06-28 Prestressing wire and method of manufacturing the same Expired - Lifetime US3196052A (en)

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GB15235/53A GB748357A (en) 1953-06-01 1953-06-01 Improvements in the manufacture of wire and the like
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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3699797A (en) * 1970-12-07 1972-10-24 Bekaert Sa Nv Hot worked steel method and product
US3718442A (en) * 1970-10-23 1973-02-27 Steel Corp Stranded steel wire structures
US3753797A (en) * 1970-07-27 1973-08-21 Kawai Musical Instr Mfg Co Process for heat treatment of metallic strings for stringed instruments
JPS5020957B1 (fr) * 1970-07-03 1975-07-18
US3964938A (en) * 1975-01-20 1976-06-22 New York Wire Mills Corporation Method and apparatus for forming high tensile steel from low and medium carbon steel
JPS5388514U (fr) * 1977-11-30 1978-07-20
US4225365A (en) * 1978-11-15 1980-09-30 Caterpillar Tractor Co. Lower bainite alloy steel article and method of making same
US4343661A (en) * 1978-11-15 1982-08-10 Caterpillar Tractor Co. Method of making a low temperature bainite steel alloy gear
US4432812A (en) * 1980-04-21 1984-02-21 Caterpillar Tractor Co. Drive train gear of lower bainite alloy steel
DE3405693A1 (de) * 1984-02-17 1985-08-22 Daimler-Benz Ag, 7000 Stuttgart Verfahren und vorrichtung zur herstellung von litzen fuer bowdenzuege
EP0260717A1 (fr) * 1986-09-19 1988-03-23 Aicher, Max, Dipl.-Ing. Procédé de fabrication de laminés en acier
US4938811A (en) * 1988-07-15 1990-07-03 Sumitomo Electric Industries, Ltd. Steel wire for a spring and method for the production thereof
US5672218A (en) * 1996-06-24 1997-09-30 Slater Steels Corporation Method of straightening metal bars having extremely low levels of residual stress after straightening operations are completed
US5762724A (en) * 1995-08-24 1998-06-09 Shinko Kosen Kogyo Kabushiki Kaisha High strength steel strand for prestressed concrete and method for manufacturing the same
US6715331B1 (en) * 2002-12-18 2004-04-06 The Goodyear Tire & Rubber Company Drawing of steel wire
CN107685083A (zh) * 2017-09-17 2018-02-13 浙江毅美材料有限公司 一种水箱拉丝机的模具冷却装置
US20200165695A1 (en) * 2017-07-17 2020-05-28 Hongduk Industrial Co., Ltd. Steel Cord and Single Steel Wire Having Excellent Straightness Quality for Reinforcing Tire and Manufacturing Method Thereof
RU2746613C1 (ru) * 2019-07-02 2021-04-16 Хондук Индастриал Ко., Лтд. Стальная проволока, для которой необходима прямолинейность, и способ ее изготовления

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DE1188108B (de) * 1958-08-02 1965-03-04 Wistra Ofenbau Ges Mit Beschra Abschreckvorrichtung fuer aus Haerte- und Vergueteoefen kommendes langgestrecktes Gut
US3312576A (en) * 1963-07-03 1967-04-04 Reynolds Metals Co Method of treating metal
JPS532975B2 (fr) * 1971-09-27 1978-02-02
JPS5324891B2 (fr) * 1972-02-16 1978-07-24
FR2288786A1 (fr) * 1974-10-25 1976-05-21 Centre Techn Ind Mecanique Procede et machine pour le traitement de pieces elancees en vue d'ameliorer leur structure interne et/ou pour les dresser
ATE87515T1 (de) * 1988-09-27 1993-04-15 Mannesmann Ag Verfahren zum warmrichten von stahlrohren.

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US2281132A (en) * 1939-09-09 1942-04-28 Leonard A Young Method of wire drawing
US2589881A (en) * 1950-02-18 1952-03-18 Lasalle Steel Co Method of producing steel products and articles
US2767836A (en) * 1955-06-27 1956-10-23 Lasalle Steel Co Process of extruding steel
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US2281132A (en) * 1939-09-09 1942-04-28 Leonard A Young Method of wire drawing
US2589881A (en) * 1950-02-18 1952-03-18 Lasalle Steel Co Method of producing steel products and articles
US2816052A (en) * 1953-11-07 1957-12-10 Hoesch Westfalenhutte Ag Method of manufacturing ribbed steel rods
US2767836A (en) * 1955-06-27 1956-10-23 Lasalle Steel Co Process of extruding steel

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5020957B1 (fr) * 1970-07-03 1975-07-18
US3753797A (en) * 1970-07-27 1973-08-21 Kawai Musical Instr Mfg Co Process for heat treatment of metallic strings for stringed instruments
US3718442A (en) * 1970-10-23 1973-02-27 Steel Corp Stranded steel wire structures
US3699797A (en) * 1970-12-07 1972-10-24 Bekaert Sa Nv Hot worked steel method and product
US3964938A (en) * 1975-01-20 1976-06-22 New York Wire Mills Corporation Method and apparatus for forming high tensile steel from low and medium carbon steel
JPS5388514U (fr) * 1977-11-30 1978-07-20
JPS5443043Y2 (fr) * 1977-11-30 1979-12-13
US4225365A (en) * 1978-11-15 1980-09-30 Caterpillar Tractor Co. Lower bainite alloy steel article and method of making same
US4343661A (en) * 1978-11-15 1982-08-10 Caterpillar Tractor Co. Method of making a low temperature bainite steel alloy gear
US4432812A (en) * 1980-04-21 1984-02-21 Caterpillar Tractor Co. Drive train gear of lower bainite alloy steel
DE3405693A1 (de) * 1984-02-17 1985-08-22 Daimler-Benz Ag, 7000 Stuttgart Verfahren und vorrichtung zur herstellung von litzen fuer bowdenzuege
EP0260717A1 (fr) * 1986-09-19 1988-03-23 Aicher, Max, Dipl.-Ing. Procédé de fabrication de laminés en acier
WO1988002031A1 (fr) * 1986-09-19 1988-03-24 Aicher, Max Procede pour la fabrication de produits en acier lamine
US4938811A (en) * 1988-07-15 1990-07-03 Sumitomo Electric Industries, Ltd. Steel wire for a spring and method for the production thereof
US5762724A (en) * 1995-08-24 1998-06-09 Shinko Kosen Kogyo Kabushiki Kaisha High strength steel strand for prestressed concrete and method for manufacturing the same
US5672218A (en) * 1996-06-24 1997-09-30 Slater Steels Corporation Method of straightening metal bars having extremely low levels of residual stress after straightening operations are completed
US6715331B1 (en) * 2002-12-18 2004-04-06 The Goodyear Tire & Rubber Company Drawing of steel wire
US20200165695A1 (en) * 2017-07-17 2020-05-28 Hongduk Industrial Co., Ltd. Steel Cord and Single Steel Wire Having Excellent Straightness Quality for Reinforcing Tire and Manufacturing Method Thereof
CN107685083A (zh) * 2017-09-17 2018-02-13 浙江毅美材料有限公司 一种水箱拉丝机的模具冷却装置
RU2746613C1 (ru) * 2019-07-02 2021-04-16 Хондук Индастриал Ко., Лтд. Стальная проволока, для которой необходима прямолинейность, и способ ее изготовления

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GB748357A (en) 1956-05-02
FR1105936A (fr) 1955-12-09

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