US3899287A - Method of heating metallic material - Google Patents

Method of heating metallic material Download PDF

Info

Publication number
US3899287A
US3899287A US336353A US33635373A US3899287A US 3899287 A US3899287 A US 3899287A US 336353 A US336353 A US 336353A US 33635373 A US33635373 A US 33635373A US 3899287 A US3899287 A US 3899287A
Authority
US
United States
Prior art keywords
furnace
gas
space
furnace space
atmosphere
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US336353A
Other languages
English (en)
Inventor
Bo Goran Hamrin
Rune Peterson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Granges Engineering AB
Original Assignee
Granges Engineering AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Granges Engineering AB filed Critical Granges Engineering AB
Application granted granted Critical
Publication of US3899287A publication Critical patent/US3899287A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • 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

Definitions

  • the furnace is heated in a manner such as to exclude the burning of fuel in the actual furnace space.
  • the quantity of gas capable of reacting with the material and entering the furnace space as the furnace is charged and discharged is restricted, so as to retain a balance between the furnace atmosphere and the material.
  • the present invention relates to a continuous method of heating metallic material the surfaces of which tends to react chemically with the furnace atmosphere when subjected to heat, in a manner such as to substantially avoid any such reaction, in which method the metallic material is heated in a furnace into which it is charged while substantially free from an oxygen-containing coatings.
  • the invention is primarily intended for the heat treatment and heating of steel ingots, billets and the like, particularly ingots and billets comprising high grade steel and containing large quantities of alloying substances, and in the following will mainly be described with reference there to. It should be understood, however, that the invention can also be applied to advantage in the heat treatment and heating of other metals which hitherto have the tendency of deleteriously reacting with or of being affected by the atmosphere in which the heating process or heat treatment process is carried out.
  • Decarbonization and scaling i.e. the depletion of carbon at the surfaces of ingots, billets, blooms etc. and the oxidation of the iron in the surface portions thereof when heating the ingots, billets, blooms etc. to hot working temperatures have always been considered practically unavoidable occurrences.
  • Decarbonization and scaling result in large quantities of waste, especially in the manufacture of highly alloyed high-grade steel, such as high-speed steel, tool steel, stainless steel etc. Because of decarbonization, it is often necessary in practice to form the ingots, billets, blooms etc. with large working tolerances, so that the decarbonized surface portions thereof can be removed by conventional machining operations such as scraping, grinding, scale turning etc.
  • the material losses caused by scaling can, in the case of highly alloyed, high-grade steels, be very significant from the aspect of economy, and costs are often increased owing to the fact that because of scaling it is often necessary to pickle the heated ingots, billets, etc. before they can be processed further.
  • the object of the invention is to provide a new and improved method in the heating of metallic material whose surface tend to react chemically with the furnace atmosphere, by which method undesirable surface reactions such as decarbonization and scaling are avoided to a high degree in a practical and economic manner.
  • the material is heated in a substantially fully gas-tight furnace, which is heated without burning fuel in the actual furnace space itself and in an atmosphere which is generally in balance with the composition of the material being heated at the heating temperature in question and substantially all of which is constantly retained in said furnace space, and by restricting the quantity of gas capable of reacting chemically with the material and entering the furnace as said material is fed into and out of the same in a manner so as to maintain the balance between the furnace atmosphere and the metallic material at such a level that only a slight, controlled degree of chemical reaction takes place between the metallic material and the gas in the furnace space.
  • the method of the present invention uses the actual material being heated to form a suitable furnace atmosphere. This is done by causing the surface layers of the metallic material to react with the gas which enters the furnace space when the material is fed into and out of the furnace and the gas which it may be necessary to charge to the furnace space in order to maintain a suitable pressure above atmospheric therein.
  • the quantity of gas entering the furnace space incidently and optionally fed there to in order to maintain said pressure is held so low, by retaining in the furnace to the highest possible extent the gas already present therein, that the surface of the metallic material is not affected to an extent which causes the surface quality of the material to depart from the requirement placed thereon.
  • the metallic material is fed in batches into and out of the furnace through at least one feed valve or lock, which is capable of being closed to the furnace space and to the surrounding atmosphere and the cubic capacity of which suitably only slightly exceeds the volume of the batch.
  • the feed valve before being placed in communication with the furnace space and while closed against the surrounding atmosphere, at least when discharging the material from the furnace and suitably also when feeding the same thereinto, can be flushed with a gas which is at least substantially inert with 'respect to the metallic material, or may also be first subjected to subpressure and then flushed with a gas which is at least substantially inert with respect to the metallic material.
  • the difference in the cubic capacity of the feed valve and the volume of the metallic material fed thereinto for charging to the furnace is maintained at such a small magnitude that the quantity of air present in the feed valve together with the material during a furnace charging operation is insufficient to react with the surface of the metal to a harmful extent, thereby rendering it unnecessary to remove air from the feed valve by flushing or to establish a subpressure therein in accordance with the aforegoing.
  • the pressure within the furnace space should be slightly higher than the pressure of the atmosphere surrounding the furnace.
  • the pressure in the furnace space is maintained at the desired level by feeding into or out of the same minor quantities of a gas which is at least substantially inert to the material in question.
  • FIG. 1 is a vertical sectional view taken through the line I-I in FIG. 2, and
  • FIG. 2 is a sectional view of the furnace plant taken through the line II-II in FIG. 1.
  • the reference numeral generally indicates a furnace which is substantially completely sealed against the surroundings and which is intended for heating rod-shaped workpieces such as ingots or bi]- lets etc. (not shown) and to which is connected an infeed valve or lock 11 and an outfeed valve or lock 12.
  • the furnace 10 is provided with a number of electric heating elements 13 which extend through the furnace roof 14 down into the furnace space 15.
  • a shield 16 comprising walls and roof prevents unintentional access to the portions of the elements 13 located above the furnace roof and having connections (not shown) for conducting electric current to the elements.
  • Other methods of heating the furnace 10 can be applied within the scope of the invention, provided that the furnace is heated without combusting fuel in the actual furnace space itself.
  • Arranged in the furnace are two roller paths comprising rollers 20 and 21 respectively, each path extending along its respective one of the walls 18, 19, and beams 22 and pusher means 23 for supporting and feeding the workpieces entering the feed valve 11 transversely through the furnace space 15 from the rollers 20 towards the rollers 21.
  • the rollers 20 and 21 are carried by shafts which are journalled externally of the furnace 10 in bearings 24 carried by bracket structures 25.
  • the pusher means 23 have the form of plates connected to the pistons of respective linear piston engines 27, via pusher rods 26 passing through the furnace wall 18, the stroke of which engines is at least such that subsequent to a workpiece resting on the rollers 20 being moved towards the rollers 21 there is provided the requisite space for feeding a new workpiece into the furnace space 15 from the feed valve 11.
  • the piston engines are placed on bracket structures 28. Sealing means (not shown) are arranged to seal between on one hand the roller shafts and the rods 26 and on the other the furnace walls 18, 19.
  • the feed valves 11 and 12 are provided at each end thereof with closure means, as indicated at 29.
  • the ref erence numerals 30 and 31 identify rollers forming part of diagrammatically illustrated roller paths for feeding workpieces into the feed valve 11 and discharging heated or heat-treated workpieces from the feed valve 12.
  • the feed valves 11, 12 are also provided with feeding mechanisms 32 for feeding the workpieces from the valve 11 to the roller paths formed by rollers 20 in the furnace 10 and for feeding the heated or heat-treated workpieces from the valve 12 to the roller paths formed by the rollers 31.
  • each of the feed valves 11, 12 there is connected a pipe stud 33, 34 or a pair of such studs, via which the air in the feed valves can be removed by suction and/or the feed valves can be flushed with a substantially inert gas.
  • the flushing gas can be introduced through the pipe studs 33 while the feed valves are in communication with the surrounding atmosphere, wherewith the stud pipes 34 can be omitted.
  • a line (not shown) through which the gas, which is substantially inert with respect to the workpieces being treated, can be charged to the furnace should the pressure in the furnace fall below a predetermined level.
  • the pressure in the furnace 10 is suitably selected so as to slightly exceed the pressure of the surrounding atmosphere.
  • the gas in the furnace space, and also the gas used for flushing the feed valves 1 1, 12, may comprise without detriment an inexpensive so-called inert gas, e.g. commercially available nitrogen gas, which contains a certain quantity of oxygen since the gas charge used for flushing the feed valves 11, 12 does not have to pass through the furnace.
  • a suitable atmosphere lacking any appreciable tendency to oxidize or to decarbonize the surface of the workpieces when heating same to the relevant temperature may be initially created by filling the furnace 10 with a substantially inert gas whose carbon and oxygen potential is subsequently adjusted so as to be substantially in balance with the composition of the material from which the workpieces are formed by allowing the gas to react with the workpieces first charged to the furnace.
  • the workpieces first charged to the furnace may therefore be oxidized or decarbonized to an appreciable extent, it is suitable to initially charge the furnace with second grade workpieces or suitably with scrap material free from oxidic surface coatings. It is also possible to initially fill the furnace with air and to create a suitable furnace atmosphere solely by heating, for example, suitable scrap material in the furnace.
  • the air is sucked and/or flushed from the feed valves 1 1, 12 while communication of the valves with the furnace is closed, the feed valves being constructed to advantage so that their cubic capacity only slightly exceeds the volume of the charge being fed into and out of the furnace, thereby considerably reducing the quantity of flushing gas required.
  • EXAMPLE 1 A high-alloy, high speed steel material having a specific surface of 1650 dm was fed each hour through a conventional furnace having an infeed lock and an out feed lock. Each lock had a capacity of 18 litres and the lock charging and discharging frequency was one batch of material per minute. As is conventional, each time i batch was fed into the infeed lock, a quantity of gas equal to times the lock capacity, i.e. 180 l of gas, was fed to the infeed lock through the furnace to displace gas present in the lock to atmosphere and to flush the batch of material in the lock. Similarly, the outfeed lock was flushed in a corresponding manner, with 180 litres of flushing gas, prior to discharging a batch of material from the furnace.
  • the gas used was N with 1.5 by volume 0
  • the total charge of oxygen reaching to approximately 325 Nl/hr. It can be readily calculated from this that 0.2 N1 of 0 was charged for each dm of material, which was far in excess of the level of 0.04 Nl per dm permitted in the case of the material in question.
  • EXAMPLE 2 The same furnace as that described in Example 1 was used under the same conditions to heat with each hour a similar material having a specific surface of 1650 dm although in this instance the locks were flushed with gas fed directly to the locks, i.e. without passing the gas through the furnace.
  • this volume of gas being 2.160 Nl/hr of the same gas.
  • the amount of oxygen charged was thus 0.02 N] per dm of material per hour. It was necessary to supply 250 N] of the above gas per hour to maintain the pressure in the furnace space. This represented an oxygen charge of 3.75 N], i.e. an addition of about 0.002 N1 0 per hr and dm which was well below the limit permitted for the material in question.
  • the furnace may comprise a walking beam furnace, a pusher type furnace or any other suitable furnace, and when an annular furnace is used in conjunction with the method of the present invention the same feed valve can be used for feeding a charge into and out of the furnace.
  • the method of the present invention can be modified in a number of ways within the scope of the following claims:
  • a method according to claim 1 maintaining the pressure in the furnace space at a predetermined level by introducing into the furnace space and removing therefrom small quantities of gas, the gas introduced being at least substantially inert with respect to said material.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Furnace Details (AREA)
  • Heat Treatment Of Articles (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Tunnel Furnaces (AREA)
US336353A 1972-02-29 1973-02-27 Method of heating metallic material Expired - Lifetime US3899287A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
SE7202543A SE378428B (it) 1972-02-29 1972-02-29

Publications (1)

Publication Number Publication Date
US3899287A true US3899287A (en) 1975-08-12

Family

ID=20260150

Family Applications (1)

Application Number Title Priority Date Filing Date
US336353A Expired - Lifetime US3899287A (en) 1972-02-29 1973-02-27 Method of heating metallic material

Country Status (7)

Country Link
US (1) US3899287A (it)
JP (1) JPS48100305A (it)
DE (1) DE2309245A1 (it)
FR (1) FR2174192A1 (it)
GB (1) GB1395864A (it)
IT (1) IT979578B (it)
SE (1) SE378428B (it)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111455151A (zh) * 2020-04-13 2020-07-28 重庆赛迪热工环保工程技术有限公司 一种侧进侧出的炉型结构

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ATA874874A (de) * 1974-10-31 1978-02-15 Ebner Ind Ofenbau Anlage zum blankgluhen von stangen und rohren aus chrom-nickelstahl oder chromstahl

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2191133A (en) * 1934-12-05 1940-02-20 Ici Ltd Apparatus for heat treating
US2253897A (en) * 1937-05-24 1941-08-26 Doderer Wilhelm Contrivance for treating materials within a gas atmosphere of increased pressure
US2421482A (en) * 1944-09-20 1947-06-03 Sentry Company Furnace
US2749106A (en) * 1950-11-28 1956-06-05 Metallurg Processes Co Protection of hot metallic bodies against oxidation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2191133A (en) * 1934-12-05 1940-02-20 Ici Ltd Apparatus for heat treating
US2253897A (en) * 1937-05-24 1941-08-26 Doderer Wilhelm Contrivance for treating materials within a gas atmosphere of increased pressure
US2421482A (en) * 1944-09-20 1947-06-03 Sentry Company Furnace
US2749106A (en) * 1950-11-28 1956-06-05 Metallurg Processes Co Protection of hot metallic bodies against oxidation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111455151A (zh) * 2020-04-13 2020-07-28 重庆赛迪热工环保工程技术有限公司 一种侧进侧出的炉型结构

Also Published As

Publication number Publication date
JPS48100305A (it) 1973-12-18
SE378428B (it) 1975-09-01
FR2174192A1 (it) 1973-10-12
IT979578B (it) 1974-09-30
GB1395864A (en) 1975-05-29
DE2309245A1 (de) 1973-09-06

Similar Documents

Publication Publication Date Title
US4397451A (en) Furnace for the heat treatment of scale-covered steel
US3899287A (en) Method of heating metallic material
ES477680A1 (es) Perfeccionamientos en laminadores en caliente para metales no ferreos.
US3239204A (en) Vacuum degassing apparatus
US3166841A (en) Descaling
US3180633A (en) Apparatus for producing ultraclean alloy steels
CN211036052U (zh) 一种型钢轧机s机架用镍钼钒合金半钢轧辊
US3746584A (en) Method for the continuous vacuum decarbonization of low carbon ferrochrome
GB1169874A (en) Method of Producing Low Carbon Non-Aging Deep Drawing Steel
KR100399234B1 (ko) 고로슬래그 첨가에 의한 열연오일슬러지의 환원철 제조방법
US2757107A (en) Method of descaling steel
US3633649A (en) Decarburization of ferrous material under low pressure at elevated temperature
JP7040499B2 (ja) リン含有物質からのリン除去方法、および、鋼の製造方法
WO1992001073A2 (en) Process for manufacturing metal products using scrap metal
KR100557893B1 (ko) 테르밋 반응을 이용한 특수합금철 제련용 반응장치
AU566397B2 (en) Ozone refining and smelting
DE2535207C3 (de) Verfahren und Vorrichtung zum Gewinnen von Stahl aus vorreduziertem kleinstückigem eisenhaltigem Material, insbesondere Pellets oder Stückerzen bzw. Eisenschwamm, in einem Elektroofen
SU814665A1 (ru) Способ абразивной обработки
SU148882A1 (ru) Способ сифонной разливки легированных и других сталей
SU871961A1 (ru) Способ ковки крупных стальных поковок
Kashakashvili et al. Intensification of processes of metal desulfurization and degassing in ladle during processing with inert gas and slag-forming mixtures.
JPH0578734A (ja) 鋼管内面の脱炭防止方法
Bongardt Reduction of waste from fabrication processes
El Nozahi Outline of the Egyptian steel industry
SU1227694A1 (ru) Способ обработки чугуна