WO2019048047A1 - Method of producing a cold drawn wire - Google Patents
Method of producing a cold drawn wire Download PDFInfo
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- WO2019048047A1 WO2019048047A1 PCT/EP2017/072511 EP2017072511W WO2019048047A1 WO 2019048047 A1 WO2019048047 A1 WO 2019048047A1 EP 2017072511 W EP2017072511 W EP 2017072511W WO 2019048047 A1 WO2019048047 A1 WO 2019048047A1
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- esr
- wire
- capsule
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- molten metal
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- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
- C21D9/525—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length for wire, for rods
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- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/12—Both compacting and sintering
- B22F3/14—Both compacting and sintering simultaneously
- B22F3/15—Hot isostatic pressing
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- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
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- B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
- B22F5/12—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of wires
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
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- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/02—Hardening articles or materials formed by forging or rolling, with no further heating beyond that required for the formation
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- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
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- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/28—Normalising
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- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
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- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
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- C21D6/00—Heat treatment of ferrous alloys
- C21D6/02—Hardening by precipitation
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- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
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- 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
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
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- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
- C22B9/16—Remelting metals
- C22B9/18—Electroslag remelting
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
- C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
- C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
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- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
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- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
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- B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
- B22F3/24—After-treatment of workpieces or articles
- B22F2003/248—Thermal after-treatment
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- B22—CASTING; POWDER METALLURGY
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- B22F9/00—Making metallic powder or suspensions thereof
- B22F9/02—Making metallic powder or suspensions thereof using physical processes
- B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
- B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
- B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
- B22F2009/0848—Melting process before atomisation
- B22F2009/0852—Electroslag melting
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- B22F2301/35—Iron
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- B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
- B22F2998/10—Processes characterised by the sequence of their steps
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- B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Definitions
- the invention relates to a method for the manufacture of a cold drawn wire and wire springs of a precipitation hardenable stainless steel, in particular of the type called 17-7 PH.
- the wire In order that the spring shall have a high fatigue resistance, the wire should not have any visible defects, which can initiate fatigue failures. Nor shall the surface layer contain any large slag inclusions or large zones containing major accumulations of smaller slag inclusions, which also can initiate failures.
- US 6,383,316 disclose a method for manufacturing a cold drawn wire in which the cast steel is remelted and subjected to an ESR treatment.
- the ESR ingots are hot worked, which is finished by wire rolling.
- the rolled wire is pickled and cold drawn.
- the ESR treatment is employed to avoid large slag inclusions and large zones containing major accumulations of smaller slag inclusions. This was a big improvement compared to prior processes.
- the present invention proposes a novel route of manufacturing 17-7 PH spring wire and wire springs.
- the new route includes casting a bulk of molten metal to provide ingots, electro slag refining the ingots to provide an ESR melt, atomising the ESR melt to provide a metal powder, hot isostatic pressing the powder into a billet, and working the billet into a wire. This new procedure reduces the size of the inclusions further.
- method includes the preparation of a bulk of molten metal, the molten metal comprising in weight %:
- the steel is intentionally alloyed with small amounts of N, preferably 0.005-0.15 % by weight, more preferably 0.01-0.15.
- the steel may also be intentionally alloyed with small amounts of Ti, V or Nb.
- weight % Preferably in weight %:
- the total amount of Ti, V or Nb is limited to 0.01-0.2 % by weight.
- the optional elements are limited to (in weight %):
- REM includes at least one the elements Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
- the bulk of molten metal is cast to the shape of ingots, or, preferably to a strand which is cut up.
- the ingot or cut-up strand are thereafter electro slag refined, so called ESR remelting, preferably after hot worked to the shape of electrodes.
- ESR Electro Slag Refining, also referred to as Electro Slag Remelting.
- a conventional slag mixture which is used according to known technique, and which at the ESR remelting process forms a melt, in which the electrode that shall be remelted is molten off drop-wise, such that the drops will sink through the slag melt to an underlying pond of molten metal, the ESR melt.
- a slag mixture can be used, which is known per se, and which contains appr 30 % of each of CaF 2 , CaO, and A1 2 0 3 and normally a certain amount of MgO in lime fraction as well as one or a few percent Si0 2 .
- the melting electrode as according to the invention, consists of a stainless 17-7 PH steel, which contains slag inclusions of varying sizes
- the ESR melt will get a different slag picture than before the remelting operation. It appears that the ESR slag functions as a screen for larger slag particles existing in the steel prior to the remelting operation. At least this appears to be true for those slags which have proved to have a detrimental effect on the fatigue strength of the spring wire, namely slags of type CaO, A1 2 0 3 , and MgO.
- the ESR melt is atomised to provide a metal powder.
- the atomization is preferably by gas atomising.
- the gas atomisation may be carried out by means of jets of nitrogen and/or of argon gas.
- the ESR melt is preferably prepared in a melting furnace is of type where the liquid metal is drained through a drain in the bottom of the furnace to an atomising chamber beneath the furnace.
- a melting furnace is of type where the liquid metal is drained through a drain in the bottom of the furnace to an atomising chamber beneath the furnace.
- the ESR melt can be conveyed, without exposing the melt to air, to a melting furnace of the type described in WO2013129996, hereby incorporated by reference.
- the liquid metal is also drained through a drain in the bottom of the furnace to an atomising chamber beneath the furnace.
- the ESR melt in the furnace can be protected by an inert gas, vacuum, or slag covering the surface of the melt.
- An alternative is to have a tiltable ESR furnace and a separate tundish, which both are arranged in an enveloping chamber containing a protective atmosphere.
- the atomising chamber arranged beneath the tundish. Also in this furnace and tundish combination the oxygen exposure of the molten metal is minimised.
- the atomised powder is preferably cooled in a protective atmosphere top avoid re oxidation.
- the atomised powder may be sieved to a desired powder gauge. For instance, max 250 ⁇ .
- Capsules are filled with the metal powder. After filling, the capsules are sealed. The capsules are thereafter optionally compacted in a cold isostatic press, e.g. Asea QI 100, at a pressure of at least 1000 bar, preferably around 4000 bar. The capsules are thereafter optionally placed in a pre-heating furnace, where the temperature is stepwise risen to a temperature of 900-1250° C, e.g. 1130° C, without being subjected to any externally applied pressure. The capsules are thereafter transferred to a cold isostatic press, e.g. Asea QI 100, at a pressure of at least 1000 bar, preferably around 4000 bar. The capsules are thereafter optionally placed in a pre-heating furnace, where the temperature is stepwise risen to a temperature of 900-1250° C, e.g. 1130° C, without being subjected to any externally applied pressure. The capsules are thereafter transferred to a cold isostatic press, e.g. Ase
- hot isostatic press e.g. HIPen Asea QI 80, where a pressure at least above 500 bar, e.g. 1000 bar, is applied at a temperature of 900-1250° C, e.g. 1150° C.
- the compaction of the capsule in the hot isostatic press provides a full density billet.
- the temperature is controlled so that the material is consolidated without presence of liquid phase.
- the cold isostatic press step as well as the following preheating step are used mainly for process economic reasons and it would very well be possible to transfer the sealed capsules directly to a hot isostatic press without prior cold pressing or preheating.
- the billet from the hot isostatic press is thereafter hot worked to rods which are ground and hot rolled to wires.
- the wires hot rolled to wires are thereafter descaled by mechanical descaling and/or chemical descaling (acid pickling).
- the descaled wire is then annealed at a temperature in the range of 900-1100 °C for 0.5 - 2 hours.
- the annealed wire is cold drawn with at least 30 % area reduction.
- the cold drawn wire can be spun to springs, preferably of a helicoidal shape.
- the springs are suitably precipitation hardened at temperature of 450-500 °C for 0.5- 2 h, followed by cooling in air.
- the structure of the material in the finished springs comprises of 50-70 volume-% tempered martensite containing precipitated phases of aluminium and nickel in the martensite, preferably AIN13, remainder austenite and max 5 % ⁇ -ferrite.
- the cross sectional shape of the cold drawn spring wires may be circular.
- the invention is not bound only to wires having such cross section, but can be applied also for wires having other shapes, i.e. wires having oval cross section, which can afford a more favourable distribution of tension in the finished springs which are spun to helicoidal shape. Rectangular cross sections may also be conceivable.
- the new route includes atomising a bulk of molten metal to provide a metal powder, hot isostatic pressing the powder into a billet, and working the billet into a wire, providing a method of producing a cold drawn wire from a particle metallurgy steel, comprising the following steps:
Abstract
Method of producing a cold drawn wire from a particle metallurgy steel, comprising the following steps: - preparation of a bulk of molten metal comprising in weight %: C 0.03-0.15, Si 0.01-1.2, Mn 0.1-1.5, Cr 15-20, Ni 5-10, Al 0.5-1.5, Optionally max 2 of elements chosen from the group of N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, Ta, B, Be, Bi, Se, Mg, Ca, Hf, V, and REM, and, using electro slag refining and atomising to provide a metal powder; - filling and sealing a capsule with the metal powder; - compacting the capsule to provide a full density billet; - hot working the billet and finishing by wire rolling; - cold drawing the annealed wire with at least 30 % area reduction.
Description
METHOD OF PRODUCING A COLD DRAWN WIRE
TECHNICAL FIELD
The invention relates to a method for the manufacture of a cold drawn wire and wire springs of a precipitation hardenable stainless steel, in particular of the type called 17-7 PH.
BACKGROUND
The precipitation stainless steel that contains appr 17 % Cr, appr 7 % Ni, and any precipitation hardening element, normally Al, was developed during the 1940'ies. It was disclosed in an article in the Iron Age, March 1950, pp 79-83. Already in this article, the suitability of the steel as a material for springs was suggested. Good spring features in combination with a good corrosion resistance have made the steel widely used as a spring material in corrosive environments. An environment of that type is injections pumps for Diesel engines, more particularly turbo Diesel engines. Springs which are used for this purpose must have a good corrosion resistance, which 17-7 PH steels have, in combination with a very high fatigue resistance of the springs. The fatigue resistance depends to a high degree on the surface of the spring wire. In order that the spring shall have a high fatigue resistance, the wire should not have any visible defects, which can initiate fatigue failures. Nor shall the surface layer contain any large slag inclusions or large zones containing major accumulations of smaller slag inclusions, which also can initiate failures.
US 6,383,316 disclose a method for manufacturing a cold drawn wire in which the cast steel is remelted and subjected to an ESR treatment. The ESR ingots are hot worked, which is finished by wire rolling. The rolled wire is pickled and cold drawn. The ESR treatment is employed to avoid large slag inclusions and large zones containing major accumulations of smaller slag inclusions. This was a big improvement compared to prior processes.
DESCRIPTION OF THE INVENTION
The present invention proposes a novel route of manufacturing 17-7 PH spring wire and wire springs. The new route includes casting a bulk of molten metal to provide ingots, electro slag refining the ingots to provide an ESR melt, atomising the ESR melt to
provide a metal powder, hot isostatic pressing the powder into a billet, and working the billet into a wire. This new procedure reduces the size of the inclusions further.
Furthermore, it essentially removes large zones containing major accumulations of smaller slag inclusions
More specifically the, method includes the preparation of a bulk of molten metal, the molten metal comprising in weight %:
C 0.03-0.15,
Si 0.01-1.2,
Mn 0.1-1.5,
Cr 15-20,
Ni 5-10,
Al 0.5-1.5,
Optionally
max 2 of elements chosen from the group of N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, TA, B, Be, Bi, Se, Mg, Ca, Hf, V, REM, and,
balance Fe apart from impurities.
According to one embodiment of the invention the steel is intentionally alloyed with small amounts of N, preferably 0.005-0.15 % by weight, more preferably 0.01-0.15. The steel may also be intentionally alloyed with small amounts of Ti, V or Nb.
Preferably in weight %:
Ti 0.01-0.1
Nb 0.01-0.1
V 0.01-0.1
Preferably the total amount of Ti, V or Nb is limited to 0.01-0.2 % by weight.
Preferably the optional elements are limited to (in weight %):
P < 0.05,
s < 0.1,
Cu < 0.5,
Co < 0.5,
W < 0.1,
Mo < 0.5,
Nb < 0.1,
Ti < 0.2,
Zr < 0.1,
Ta < 0.1,
B < 0.1,
Be < 0.1,
Bi < 0.1,
Se < 0.1,
Mg < 0.1,
Ca < 0.1,
Hf < 0.1,
V < 0.1,
REM < 0.2
REM includes at least one the elements Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu.
The bulk of molten metal is cast to the shape of ingots, or, preferably to a strand which is cut up. The ingot or cut-up strand are thereafter electro slag refined, so called ESR remelting, preferably after hot worked to the shape of electrodes.
ESR stands for Electro Slag Refining, also referred to as Electro Slag Remelting. At the ESR treatment there can be used a conventional slag mixture which is used according to known technique, and which at the ESR remelting process forms a melt, in which the electrode that shall be remelted is molten off drop-wise, such that the drops will sink through the slag melt to an underlying pond of molten metal, the ESR melt. For example, a slag mixture can be used, which is known per se, and which contains appr 30 % of each of CaF2, CaO, and A1203 and normally a certain amount of MgO in lime fraction as well as one or a few percent Si02.
In the case when the melting electrode, as according to the invention, consists of a stainless 17-7 PH steel, which contains slag inclusions of varying sizes, the ESR melt will get a different slag picture than before the remelting operation. It appears that the ESR slag functions as a screen for larger slag particles existing in the steel prior to the remelting operation. At least this appears to be true for those slags which have proved to have a detrimental effect on the fatigue strength of the spring wire, namely slags of type CaO, A1203, and MgO. While the smaller slag inclusions become more evenly distributed and possible zones of slag accumulations become smaller and therefore more harmless, the amount of smaller slag inclusions of this type in the remelted material is influenced only to a low degree.
During the ESR remelting operation, a certain amount of that aluminium, which was added in connection with the initial preparation of the molten metal, can be lost.
Therefore, in connection with the ESR remelting operation, more aluminium ought to be supplied to the melting pond for the replacement of any losses, so that the ESR melt obtained after the ESR remelting operation will contain 0.5-1.5 Al.
The ESR melt is atomised to provide a metal powder. The atomization is preferably by gas atomising. The gas atomisation may be carried out by means of jets of nitrogen and/or of argon gas.
The ESR melt is preferably prepared in a melting furnace is of type where the liquid metal is drained through a drain in the bottom of the furnace to an atomising chamber beneath the furnace. For instance, using an ESR-CIG from ALD Vacuum technologies GMBH, but instead of spray forming, atomising to provide a metal powder.
Alternatively, the ESR melt can be conveyed, without exposing the melt to air, to a melting furnace of the type described in WO2013129996, hereby incorporated by reference. In this of type furnace the liquid metal is also drained through a drain in the bottom of the furnace to an atomising chamber beneath the furnace. The ESR melt in the furnace can be protected by an inert gas, vacuum, or slag covering the surface of the melt.
An alternative is to have a tiltable ESR furnace and a separate tundish, which both are arranged in an enveloping chamber containing a protective atmosphere. The atomising chamber arranged beneath the tundish. Also in this furnace and tundish combination the oxygen exposure of the molten metal is minimised.
After atomisation, the atomised powder is preferably cooled in a protective atmosphere top avoid re oxidation. Optionally the atomised powder may be sieved to a desired powder gauge. For instance, max 250 μιη.
Capsules are filled with the metal powder. After filling, the capsules are sealed. The capsules are thereafter optionally compacted in a cold isostatic press, e.g. Asea QI 100, at a pressure of at least 1000 bar, preferably around 4000 bar. The capsules are thereafter optionally placed in a pre-heating furnace, where the temperature is stepwise
risen to a temperature of 900-1250° C, e.g. 1130° C, without being subjected to any externally applied pressure. The capsules are thereafter transferred to a
hot isostatic press, e.g. HIPen Asea QI 80, where a pressure at least above 500 bar, e.g. 1000 bar, is applied at a temperature of 900-1250° C, e.g. 1150° C. The compaction of the capsule in the hot isostatic press provides a full density billet. Preferably, the temperature is controlled so that the material is consolidated without presence of liquid phase. The cold isostatic press step as well as the following preheating step are used mainly for process economic reasons and it would very well be possible to transfer the sealed capsules directly to a hot isostatic press without prior cold pressing or preheating.
The billet from the hot isostatic press is thereafter hot worked to rods which are ground and hot rolled to wires. The wires hot rolled to wires are thereafter descaled by mechanical descaling and/or chemical descaling (acid pickling). The descaled wire is then annealed at a temperature in the range of 900-1100 °C for 0.5 - 2 hours. The annealed wire is cold drawn with at least 30 % area reduction.
The cold drawn wire can be spun to springs, preferably of a helicoidal shape. The springs are suitably precipitation hardened at temperature of 450-500 °C for 0.5- 2 h, followed by cooling in air.
The structure of the material in the finished springs comprises of 50-70 volume-% tempered martensite containing precipitated phases of aluminium and nickel in the martensite, preferably AIN13, remainder austenite and max 5 % δ-ferrite.
The cross sectional shape of the cold drawn spring wires may be circular. The invention, however, is not bound only to wires having such cross section, but can be applied also for wires having other shapes, i.e. wires having oval cross section, which can afford a more favourable distribution of tension in the finished springs which are spun to helicoidal shape. Rectangular cross sections may also be conceivable.
According to a modification of the invention the new route includes atomising a bulk of molten metal to provide a metal powder, hot isostatic pressing the powder into a billet, and working the billet into a wire, providing a method of producing a cold drawn wire from a particle metallurgy steel, comprising the following steps:
preparation of a bulk of molten metal comprising in weight %:
C 0.03-0.15,
Si 0.01-1.2,
Mn 0.1-1.5,
Cr 15-20,
Ni 5-10,
Al 0.5-1.5,
Optionally
max 2 of elements chosen from the group of: N, P, S, Cu, Co, W, Mo,
Nb, Ti,
Zr, TA, B, Be, Bi, Se, Mg, Ca, Hf, V, and REM,
and,
balance Fe apart from impurities;
atomising the molten metal and thereby providing a metal powder; filling a capsule with the metal powder;
- sealing the capsule;
optionally compacting said capsule in a cold isostatic press;
optionally preheating said capsule;
compacting the capsule in a hot isostatic press to provide a full density billet;
- hot working the billet and finishing by wire rolling;
descaling the resulting rolled wire;
annealing the descaled wire; and
cold drawing the annealed wire with at least 30 % area reduction.
Claims
1. Method of producing a cold drawn wire from a particle metallurgy steel,
comprising the following steps:
preparation of a bulk of molten metal comprising in weight %:
C 0.03-0.15,
Si 0.01-1.2,
Mn 0.1-1.5,
Cr 15-20,
Ni 5-10,
Al 0.5-1.5,
Optionally
max 2 of elements chosen from the group of N, P, S, Cu, Co, W, Mo,Nb,
Ti,Zr, Ta, B, Be, Bi, Se, Mg, Ca, Hf, V, and REM,
and,
balance Fe apart from impurities;
casting the prepared molten metal to the shape of ingots, or, preferably to a strand which is cut up;
electro slag refining, so called ESR remelting, of said ingot or cut-up strand, preferably after hot working to the shape of electrodes, providing an ESR melt or for the formation of ESR ingots and remelting the ESR ingots;
atomising the ESR melt and thereby providing a metal powder;
filling a capsule with the metal powder;
sealing the capsule;
- optionally compacting said capsule in a cold isostatic press;
optionally preheating said capsule;
compacting the capsule in a hot isostatic press to provide a full density billet;
hot working the billet and finishing by wire rolling;
- descaling the resulting rolled wire;
annealing the descaled wire; and
cold drawing the annealed wire with at least 30 % area reduction.
The method according to claim 1 , wherein the bulk of molten metal comprises in weight %:
N 0.005-0.15, preferably 0.01-0.15.
The method according to claim 1 , wherein the bulk of molten metal comprises in
%:
P <0.05,
s <0.1,
Cu <0.5,
Co <0.5,
W <0.1,
Mo <0.5,
Nb <0.1,
Ti <0.2,
Zr <0.1,
Ta <0.1,
B <0.1,
Be <0.1,
Bi <0.1,
Se <0.1,
Mg <0.1,
Ca <0.1,
Hf <0.1,
V <0.1,
REM < 0.2.
The method according to any one of claims 1-3, wherein the bulk of molten metal comprises at least one of the following elements:
Ti 0.01-0.1;
Nb 0.01-0.1;
V 0.01-0.1;
and fulfilling the condition
Ti+Nb+V 0.01-0.2.
Method according to any one of claims 1-4, wherein the method further comprises
-atomising the ESR melt in an atomising chamber beneath an ESR furnace.
The method according to any one of claims 1-4, wherein the method further comprises:
protecting the remelted ESR ingots in an inert gas, vacuum, or by a slag covering the surface of the melt;
atomising the remelted ESR ingots by draining the liquid metal through a drain in the bottom of a furnace containing the melt to an atomising chamber.
Method for producing springs comprising the steps of:
- producing a cold drawn wire according to any one of claims 1-6;
spinning springs from the cold drawn wire, preferably to a helicoidal shape;
precipitation hardening the springs, preferably at temperature of 450-500 °C for 0.5- 2 h.
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
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CN201780096303.XA CN111315905A (en) | 2017-09-07 | 2017-09-07 | Method for producing cold-drawn wire |
JP2020535291A JP2020533490A (en) | 2017-09-07 | 2017-09-07 | Methods for manufacturing cold drawn wire |
EP17762138.0A EP3679168A1 (en) | 2017-09-07 | 2017-09-07 | Method of producing a cold drawn wire |
US16/645,303 US20210032719A1 (en) | 2017-09-07 | 2017-09-07 | Method of producing a cold drawn wire |
PCT/EP2017/072511 WO2019048047A1 (en) | 2017-09-07 | 2017-09-07 | Method of producing a cold drawn wire |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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PCT/EP2017/072511 WO2019048047A1 (en) | 2017-09-07 | 2017-09-07 | Method of producing a cold drawn wire |
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WO2019048047A1 true WO2019048047A1 (en) | 2019-03-14 |
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US (1) | US20210032719A1 (en) |
EP (1) | EP3679168A1 (en) |
JP (1) | JP2020533490A (en) |
CN (1) | CN111315905A (en) |
WO (1) | WO2019048047A1 (en) |
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JPH04311506A (en) * | 1991-04-08 | 1992-11-04 | Hitachi Metals Ltd | Wire rod for piston ring |
JPH0525591A (en) * | 1991-07-16 | 1993-02-02 | Hitachi Metals Ltd | Wire for piston ring and its manufacture |
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CN106715008A (en) * | 2014-06-27 | 2017-05-24 | 诺沃皮尼奥内股份有限公司 | Component of a turbomachine, turbomachine and process for making the same |
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2017
- 2017-09-07 JP JP2020535291A patent/JP2020533490A/en active Pending
- 2017-09-07 EP EP17762138.0A patent/EP3679168A1/en not_active Withdrawn
- 2017-09-07 US US16/645,303 patent/US20210032719A1/en not_active Abandoned
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EP3679168A1 (en) | 2020-07-15 |
US20210032719A1 (en) | 2021-02-04 |
JP2020533490A (en) | 2020-11-19 |
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