Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21B—ROLLING OF METAL
  • B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
  • B21B3/02—Rolling special iron alloys, e.g. stainless steel
• • 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
  • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
  • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
  • C21D1/76—Adjusting the composition of the atmosphere
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/10—Reduction of greenhouse gas [GHG] emissions
  • Y02P10/122—Reduction of greenhouse gas [GHG] emissions by capturing or storing CO2

Definitions

• the present invention relates generally to methods for producing hot-worked steel articles, and more particularly to a method for producing a hot-worked, tellurium-containing steel article under conditions which minimize surface checking of the steel article.
• a steel article normally undergoes a series of hotworking operations between the as-cast stage of the steel and the final marketable stage in which the steel is in the form of a bar, for example.
• the steel Before each hot-working operation, the steel normally undergoes a heating operation to render the steel more susceptible to deformation.
• the ingot is generally heated in what is known as a soaking pit prior to deformation of the ingot into an intermediate stage, such as a bloom; the bloom is typically subjected to a preheating operation before it is deformed by hot-rolling into a further intermediate stage, such as a billet; and the billet is typically subjected to a preheating operation before the billet is deformed by hotrolling into a bar.
• the ingot, the bloom and the billet are all unfinished forms of steel.
• Tellurium is added to steel to increase the steels machinability.
• a problem associated with tellurium-containing steels is that these steels are susceptible to a hotworking-caused defect reflected in checking or cracking at the surface of the steel article undergoing hot-working.
• hot-Working-caused defect in tellurium-containing steels is aggravated when the tellurium-containing steel is heated (prior to hot-working) in an oxidizing atmosphere, and that this is especially so when the atmosphere contains water vapor.
• hot-working-caused surface defects in telluriumcontaining steels are minimized by performing the heating operation, to which the telluriurn-containing steel is subjected prior to hot-working, in an atmosphere in which oxidizing gases are maintained at a minimum, and especially in which water vapor (other than the immediate product of combustion of fuels containing hydrocarbons) is minimized to less than three percent and preferably less than two percent, by volume.
• the method of the present invention applies to tellurium-containing carbon and alloy steels, and the carbon or alloy steel may contain either or both of sulphur and lead as additional machinabilitydncreasing ingredients.
• tellurium-containing steels to which the present invention would apply, are described in Holowaty U.S. Letters Patent No. 3,152,889.
• Typical carbon steels to which tellurium may be added are disclosed on pages 817-18 of The Making, Shaping and Treating of Steel, United States Steel Corporation, Pittsburgh, Pa., 1957; and typical examples of alloy steels to which tellurium may be added are disclosed on pages ICC 827-9 of the same publication.
• the invention is applicable to tellurium-containing steels having a base composition (i.e., Without tellurium) identified by AISI Nos. 1018, 1040, 1045, 1117, 1213, 12L14, 1215, 4140, 4142 and 8620.
• a typical sequence of hot-working operations for reducing tellurium-containing plain carbon steel from ingot form to bar form includes heating the ingot, in a soaking pit of conventional construction, until the steel is at a temperature in the range 2350-2400" F. and then subjecting the heated steel ingot to a hot-working operation to reduce the ingot to a bloom, with the steel undergoing hot-Working until the steel is typically at a temperature in the range 2080-2120" F.
• blooms are typically subjected to a reheating operation, in a reheating furnace of conventional construction, until the temperature of the bloom is in the range 19002200 F., following which the bloom is subjected to hot-working with the temperature of the bloom at the time hot-working thereof is finished being in excess of 1800 F.
• the typical product of a hot-working operation having a bloom as its starting product is a billet.
• a hot-working operation Before the billet is subjected to a hot-working operation, it is usually preheated, in a furnace of conventional construction, until the billet has a temperature in the range 1900-2200 F.; and the billet is then subjected to a hot-working operation which produces a bar, for example, and the temperature of the bar at the finish of the hot-Working operation is in the range 1750-2000" F.
• heating and hot-working operations are typical for many tellurium-containing plain carbon steels, e.g., a plain carbon steel containing up to 0.13 wt. percent carbon, 0.80-1.20 wt. percent manganese, 0.04-0.09 Wt. percent phosphorus, 0.25-0.35 wt. percent sulphur, 0.15-0.35 wt. percent lead and 0.04-0.06 Wt. percent tellurium. Variations in heating and hot-working conditions may be necessary for particular compositions of steels.
• a method in accordance with the present invention comprises minimizing or eliminating the oxidizing gases in the heating atmosphere.
• the optimum conditions would be to heat the tellurium-containing steel ingot or bloom or billet, or Whatever the shape may be, in an inert gas atmosphere (e.g., nit-rogen or a rare gas such as argon) or in an atmosphere consisting of endothermic gases (e.g., carbon monoxide or hydrogen) and utilize electricity as the heating medium (e.g., electric radiant heating coils).
• an inert gas atmosphere e.g., nit-rogen or a rare gas such as argon
• endothermic gases e.g., carbon monoxide or hydrogen
• electricity e.g., electric radiant heating coils
• the use of radiant heating coils as the source of heat energy eliminates one source of the oxidizing gases, H 0 and CO both of which are the product of combustion of hydrocarboncontaining fuels such as natural gas, blast furnace gas, coke oven gas, or oil, all of which are typically used to fire furnaces normally utilized in the heating of steel articles preparatory to a hot-Working
• furnaces utilized for preheating are of a conventional construction and use natural gas, oil, blast furnace gas, etc., as fuel, the presence, in the furnace atmosphere, of some 11 0 resulting from combustion cannot be avoided.
• the H 0 content from a; combustion may be as high as 15%. Therefore, precautions should especially be taken to minimize other sources of water content within the furnace in which the heating operation is conducted.
• water of condensation sometimes accumulates in the cooled-off soaking pit, between heating operations; and this water should be drained from the soaking pit prior to the heating of the ingot.
• soaking pits of the regenerative type typically embodiments of which are illustrated at pages 401-6 of The making, Shaping and Treating of Steel, supra
• water will seep into the checkerboard lines through which air is passed for preheating prior to combustion with the fuel; and steps should be taken to minimize this seepage and/or to remove seepage water from the air fiues. Water may also accumulate in the fuel line leading to the soaking it, so that the fuel line should 'be drained periodically.
• billets or blooms which are dry at the time they are placed in the reheating furnace. Often times, the billets or blooms are stored in outside locations where they are exposed to rain or snow, and the surface of the steel is wet at the time the reheating furnace is ready to receive the steel. To prevent the introduction of water vapor into the furnace through this medium, the billet or bloom surfaces should be dry and this can be accomplished by storing the billets or blooms indoors, or by subjecting the billets or blooms to a drying operation before putting them in the reheating furnaces.
• blast furnace gas is conventionally subjected to a wetting operation following the withdrawal of the gas from the blast furnace.
• the purpose of the wetting operation is to remove certain impurities, and this operation leaves the gas supersaturated with water vapor.
• the blast furnace gas should be dried or dehumidified before utilizing it as a fuel in a soaking pit or reheating furnace. This can be accomplished, for example, by cooling the gas to condense the water vapor and reduce the H content of the gas.
• H O extraneous H O (i.e., H O other than that which is the immediate product of combustion) should be prevented from becoming a part of the furnace atmosphere.
• An optimum condition for a furnace atmosphere in which tellurium-containing steels are heated prior to hotworking is an atmosphere devoid of water, both extraneous and the product of combustion. If this optimum situation cannot be obtained, the extraneous water vapor should be kept out of the furnace atmosphere; and if this is not entirely possible, then the extraneous water vapor content should preferably be less than 2%, by volume, or, at the very most, less than 3%, by volume.
• the present invention is also applicable to minimize similar defects in selenium-containing steels or in steels containing both tellurium and selenium, these two elements being used interchangeably in steels for the same purpose.
• a method for producing a hot-worked steel article containing at least one ingredient selected from the group consisting of tellurium and selenium comprising the steps of:
• said atmosphere-controlling step comprising excluding extraneous water vapor from the furnace atmosphere.
• said atmosphere-controlling step comprising removing
• said atmosphere-controlling step comprising removing water which has seeped into said preheating flues.
• said atmosphere-controlling step comprising removing
• a method for producing a hot-worked steel article containing at least one ingredient selected from the group consisting of tellurium and selenium comprising the steps of:
• a method for producing a hot-worked steel article containing at least one ingredient selected from the group consisting of tellurium and selenium comprising the steps of:

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Furnace Details (AREA)

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Cited By (6)

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Citations (5)

• 1965
  • 1965-02-01 US US429612A patent/US3365922A/en not_active Expired - Lifetime
• 1966
  • 1966-01-21 DE DE19661508407 patent/DE1508407B1/de not_active Withdrawn
  • 1966-01-24 AT AT61966A patent/AT276459B/de active
  • 1966-01-25 ES ES0322206A patent/ES322206A1/es not_active Expired
  • 1966-01-26 FR FR47286A patent/FR1465925A/fr not_active Expired
  • 1966-01-26 DK DK42966AA patent/DK138375B/da unknown
  • 1966-01-27 CH CH114966A patent/CH454198A/fr unknown
  • 1966-01-31 SE SE1214/66A patent/SE315616B/xx unknown
  • 1966-01-31 GB GB4158/66A patent/GB1111608A/en not_active Expired
  • 1966-01-31 BE BE675803D patent/BE675803A/xx unknown
  • 1966-02-01 NL NL6601281A patent/NL6601281A/xx unknown
  • 1966-02-01 NO NO161508A patent/NO115960B/no unknown
  • 1966-02-01 LU LU50362A patent/LU50362A1/xx unknown

Patent Citations (5)

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