JP2020533490A - Methods for manufacturing cold drawn wire - Google Patents

Abstract

A method for producing a wire cold drawn from a steel for particle metallurgy, in which the weight is C 0.03 to 0.15, Si 0.01 to 1.2, Mn 0.1 to 1. 5, Cr 15 to 20, Ni 5 to 10, Al 0.5 to 1.5, optionally N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, TA, B, Be, The process of preparing a bulk of a molten metal containing up to two elements selected from the group Bi, Se, Mg, Ca, Hf, V, and REM; using electroslag refining and atomization to provide the metal powder. Steps, filling and encapsulating capsules with metal powder; compression molding of capsules to provide billets of sufficient density; hot working of billets and finishing by wire rolling; at least 30% A method comprising the step of cold drawing an annealed wire having area reduction.

Description

The present invention relates to methods for making cold drawn wires and wire springs of stainless steel that are precipitation harden, especially of the type referred to as 17-7 PH.

Hardened stainless steels containing about 17% Cr, about 7% Ni, and any precipitation hardening element, usually Al, were developed in the 1940s. It is disclosed in Non-Patent Document 1. Already in this document, the suitability of steel as a material for springs has been proposed. Good spring properties combined with good corrosion resistance make steel widely used as a spring material in corrosive environments. This type of environment is an injection pump for diesel engines, more specifically for turbo diesel engines. The springs used for this purpose must have good corrosion resistance, which is what 17-7PH steel has, combined with the very high fatigue resistance of the spring.

Fatigue resistance is highly dependent on the surface of the spring wire. In order for the spring to have high fatigue resistance properties, the wire should not have any visible defects that could cause fatigue failure. The surface layer should also not contain large zones (which can also cause destruction) containing a wide range of deposits of any large slag entrainment or smaller slag entrainment.

Patent Document 1 discloses a method for producing a cold drawn wire, where the cast steel is remelted and subjected to ESR treatment. The ESR ingot is hot worked and finished by rolling wire. The rolled wire is pickled and cold drawn. The ESR treatment is performed to avoid large zones containing large slag entrainment and widespread deposition of smaller slag entrainment. This was a major improvement over the previous process.

U.S. Pat. No. 6,383,316

The Iron Age, March 1950, pp79-83

The present invention proposes novel routes for manufacturing 17-7PH spring wires and wire springs. New routes are casting bulk of molten metal to provide ingots, electroslag refining ingots to provide ESR melts, atomizing ESR melts to provide metal powders. This includes hot hydrostatic pressing of the powder into billets and processing of billets into wires. This new procedure further reduces the size of entrainment. In addition, it essentially eliminates large zones containing a wide range of deposits with smaller slag involvement.

任意には、
Ｎ、Ｐ、Ｓ、Ｃｕ、Ｃｏ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉ、Ｚｒ、ＴＡ、Ｂ、Ｂｅ、Ｂｉ、Ｓｅ、Ｍｇ、Ｃａ、Ｈｆ、Ｖ、ＲＥＭの群から選択される最大２つの元素、および
不純物を除いて残部がＦｅ
を含む。 More specifically, the method comprises the preparation of a bulk of the molten metal, wherein the molten metal is by weight%.

Optionally,
Up to two elements selected 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 the rest is Fe except for impurities
including.

である。
好ましくは、Ｔｉ、ＶまたはＮｂの総量は、０．０１〜０．２重量％までに限定される。
好ましくは、任意の元素は重量％で、

に限定される。
ＲＥＭは、Ｓｃ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍ、Ｓｍ、Ｅｕ、Ｇｄ、Ｙ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、およびＬｕの元素のうち少なくとも一つを含む。 In one embodiment of the invention, the steel is deliberately alloyed with a small amount of N, preferably 0.005 to 0.15% by weight, more preferably 0.01 to 0.15% by weight. The steel may also be deliberately alloyed with a small amount of Ti, V or Nb.
Preferably by weight

Is.
Preferably, the total amount of Ti, V or Nb is limited to 0.01-0.2% by weight.
Preferably, any element is by weight%

Limited to.
REM contains at least one of the elements Sc, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Y, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

The bulk of the molten metal is cast in the form of an ingot, or preferably into a strand that is cut up. The ingot or cut-up strands are then hot-worked, preferably in the form of electrodes, and then electroslag refined, so-called ESR remelted.

ESR is an abbreviation for electroslag refining and is also referred to as electroslag remelting. Used according to known techniques in the ESR process, and in the ESR remelting process it forms a melt and is remelted so that the droplets sink through the slag melt into the underlying molten metal pond. Conventional slag mixtures, ESR melts, in which the electrodes are melted into droplets can be used. For example, a known slag mixture containing about 30% CaF ₂ , CaO, and Al ₂ O ₃ respectively and usually a constant amount of MgO and 1% to a few% SiO ₂ in the lime fraction. A slag mixture can be used.

According to the present invention, if the melting electrode is made of stainless 17-7PH steel with slag entrainment of various sizes, the ESR melt will obtain a different slag image than before the remelt operation. The ESR slag appears to function as a screen for the larger slag particles present in the steel prior to the remelt operation. At the very least, this seems to be true for slags of the CaO, Al ₂ O ₃ and MgO types that have proven to have a detrimental effect on the fatigue strength of spring wires. While smaller slag entrainments are more evenly distributed and possible zones of slag deposition are smaller and therefore more harmless, the amount of smaller slag entrainments of this type in the remelted material is to a lesser extent. Only affected.

During the ESR remelt operation, a certain amount of aluminum added in connection with the initial preparation of the molten metal can be lost. Therefore, in connection with the ESR remelt operation, more aluminum should be supplied to the molten pool to fill the loss, which results in an ESR melt obtained after the ESR remelt operation of 0.5-1. Will contain 5Al.

The ESR melt is atomized to provide a metal powder. Atomization is preferably by gas atomization. Gas atomization can be done with a jet of nitrogen and / or argon gas.

The ESR melt is preferably prepared in a type of melting furnace in which the liquid metal is discharged through the drain at the bottom of the furnace into the atomizing chamber below the furnace. For example, ESR-CIG manufactured by ALD Vacum technologies GMBH is used, but atomized to provide a metal powder instead of spray formation.

Alternatively, the ESR melt may be transported to a melting furnace of the type described in WO 2013/129996 incorporated herein by reference without exposing the melt to air. In these types of furnaces, liquid metal is also discharged through the drain at the bottom of the furnace into the atomizing chamber below the furnace. The ESR melt in the furnace can be protected by an inert gas, vacuum, or slag over the surface of the melt.

Alternatively, a tiltable ESR furnace and a separate tundish may be provided, both of which are provided in an encapsulation chamber containing a protective environment. The atomizing chamber is provided under the tundish. Also, in this furnace and tundish combination, exposure of the molten metal to oxygen is minimized.

After atomization, the atomized powder is preferably cooled in a protective environment to avoid reoxidation. Optionally, the atomized powder can be screened to the desired powder size. For example, the maximum is 250 μm.

The capsule is filled with metal powder. After filling, the capsule is encapsulated, the capsule is then compression molded, optionally in a cold hydrostatic press such as Asia QI 100, at a pressure of at least 1000 bar, preferably about 4000 bar. The capsule is then optionally placed in a preheating furnace, where the temperature is stepped up to 900-1250 ° C., eg 1130 ° C., without external pressure. The capsules are then transferred to a hot hydrostatic press, such as the HI Pen Asia QI 80, where a pressure of at least 500 bar, eg 1000 bar, is applied at a temperature of 900-1250 ° C, eg 1150 ° C. Compression molding of capsules in a hot hydrostatic press provides a sufficiently dense billet. Preferably, the temperature is controlled so that the material solidifies in the absence of a liquid phase. The cold hydrostatic press process and subsequent preheating steps are mainly used in the process for economic reasons, and the encapsulated capsules directly to the hot hydrostatic press without prior cold pressing or preheating. You can probably move it.

Billets from a hot hydrostatic press are then hot-worked into ground rods and hot-rolled into wires. The wire hot-rolled into wire is then descaled by mechanical descaling and / or chemical descaling (pickling).

The descaled wire is then annealed at a temperature in the range 900-1000 ° C. for 0.5-2 hours. The annealed wire is cold drawn and has an area reduction of at least 30%.

The cold drawn wire is wound around a spring, preferably a spirally shaped spring. The springs are appropriately precipitation hardened at a temperature of 450 to 500 ° C. for 0.5 to 2 hours and then cooled in air.

The structure of the material in the finished spring is 50-70% by volume tempered martensite containing a precipitated phase of aluminum and nickel, preferably AlNi ₃ in martensite, as well as austenite as the balance and up to 5% δ-ferrite. including.

The cross-sectional shape of the cold drawn spring wire may be circular. However, the present invention is not limited to wires having such a cross section, but wires having other shapes that can provide a more favorable tension distribution in a finished spring wound in a spiral shape, i.e. oval. It can also be applied to wires having a cross section of. A rectangular cross section can also be envisioned.

任意には、
Ｎ、Ｐ、Ｓ、Ｃｕ、Ｃｏ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉ、Ｚｒ、ＴＡ、Ｂ、Ｂｅ、Ｂｉ、Ｓｅ、Ｍｇ、Ｃａ、Ｈｆ、Ｖ、およびＲＥＭの群から選択される最大２つの元素、および
不純物を除いて残部がＦｅ
を含む溶融金属のバルクの調製；
溶融金属のアトマイズ化およびそれによって金属粉末を提供すること；
金属粉末を用いたカプセルの充填；
カプセルの封入；
任意には、冷間静水圧プレスによる該カプセルの圧縮成形；
任意には、該カプセルの前加熱；
十分な密度のビレットを提供するための、熱間静水圧プレスによるカプセルの圧縮成形；
ビレットの熱間加工およびワイヤ圧延による仕上げ；
得られた圧延ワイヤの脱スケール化；
脱スケール化されたワイヤのアニーリング；および
少なくとも３０％のエリア減少を有するアニールされたワイヤの冷間引抜き
を含む方法を提供する。 Following a variant of the invention, the novel pathways are atomizing the bulk of the molten metal to provide a metal powder, hot hydrostatic pressing of the powder into billets, and processing of billets into wires. A method for producing cold drawn wire from particle metallurgical steel, including the following steps:
By weight%

Optionally,
Up to two elements selected from the group N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, TA, B, Be, Bi, Se, Mg, Ca, Hf, V, and REM. , And the rest is Fe except for impurities
Preparation of bulk of molten metal containing;
Atomizing molten metal and thereby providing metal powder;
Filling capsules with metal powder;
Encapsulation;
Optionally, compression molding of the capsule by a cold hydrostatic press;
Optionally, preheating the capsule;
Compression molding of capsules by hot hydrostatic press to provide billets of sufficient density;
Hot working of billets and finishing by wire rolling;
Descaling of the obtained rolled wire;
Descaling wire annealing; and methods including cold drawing of annealed wire with an area reduction of at least 30% are provided.

任意には、
Ｎ、Ｐ、Ｓ、Ｃｕ、Ｃｏ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉ、Ｚｒ、Ｔａ、Ｂ、Ｂｅ、Ｂｉ、Ｓｅ、Ｍｇ、Ｃａ、Ｈｆ、Ｖ、ＲＥＭの群から選択される最大２つの元素、および
不純物を除いて残部がＦｅ
を含む。 More specifically, the method comprises the preparation of a bulk of the molten metal, wherein the molten metal is by weight%.

Optionally,
Up to two elements selected from the group N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, Ta , B, Be, Bi, Se, Mg, Ca, Hf, V, REM , And the rest is Fe except for impurities
including.

任意には、
Ｎ、Ｐ、Ｓ、Ｃｕ、Ｃｏ、Ｗ、Ｍｏ、Ｎｂ、Ｔｉ、Ｚｒ、Ｔａ、Ｂ、Ｂｅ、Ｂｉ、Ｓｅ、Ｍｇ、Ｃａ、Ｈｆ、Ｖ、およびＲＥＭの群から選択される最大２つの元素、および
不純物を除いて残部がＦｅ
を含む溶融金属のバルクの調製；
溶融金属のアトマイズ化およびそれによって金属粉末を提供すること；
金属粉末を用いたカプセルの充填；
カプセルの封入；
任意には、冷間静水圧プレスによる該カプセルの圧縮成形；
任意には、該カプセルの前加熱；
十分な密度のビレットを提供するための、熱間静水圧プレスによるカプセルの圧縮成形；
ビレットの熱間加工およびワイヤ圧延による仕上げ；
得られた圧延ワイヤの脱スケール化；
脱スケール化されたワイヤのアニーリング；および
少なくとも３０％のエリア減少を有するアニールされたワイヤの冷間引抜き
を含む方法を提供する。 Following a variant of the invention, the novel pathways are atomizing the bulk of the molten metal to provide a metal powder, hot hydrostatic pressing of the powder into billets, and processing of billets into wires. A method for producing cold drawn wire from particle metallurgical steel, including the following steps:
By weight%

Optionally,
Up to two selected from the group N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, Ta , B, Be, Bi, Se, Mg, Ca, Hf, V, and REM. The rest is Fe except for elements and impurities
Preparation of bulk of molten metal containing;
Atomizing molten metal and thereby providing metal powder;
Filling capsules with metal powder;
Encapsulation;
Optionally, compression molding of the capsule by a cold hydrostatic press;
Optionally, preheating the capsule;
Compression molding of capsules by hot hydrostatic press to provide billets of sufficient density;
Hot working of billets and finishing by wire rolling;
Descaling of the obtained rolled wire;
Descaling wire annealing; and methods including cold drawing of annealed wire with an area reduction of at least 30% are provided.

Claims (7)

A method for producing cold drawn wire from particle metallurgical steel, the following steps:
By weight%

Optionally,
Up to two elements selected from the group N, P, S, Cu, Co, W, Mo, Nb, Ti, Zr, TA, B, Be, Bi, Se, Mg, Ca, Hf, V, and REM. , And the rest is Fe except for impurities
Bulk preparation process of molten metal containing
The step of casting the prepared molten metal in the form of an ingot, or preferably into a cut-up strand;
Electroslag refining, a so-called ESR remelting step after hot working of the ingot or cut-up strand, preferably in the form of an electrode, to provide an ESR melt or to form an ESR ingot and Steps for remelting the ESR ingot;
The step of atomizing the ESR melt and thereby providing a metal powder;
The process of filling capsules with metal powder;
The process of encapsulating the capsule;
Optionally, a step of compression molding the capsule by a cold hydrostatic press;
Optionally, a step of preheating the capsule;
The step of compression molding the capsule with a hot hydrostatic press to provide a billet of sufficient density;
The process of hot-working the billet and finishing by wire rolling;
Step of descaling the obtained rolled wire;
A method comprising the step of annealing the descaled wire; and the step of cold drawing the annealed wire having an area reduction of at least 30%. The bulk of the molten metal is by weight%
N 0.005-0.15. Preferably 0.01 to 0.15
The method according to claim 1. The bulk of the molten metal is by weight%

The method according to claim 1. The bulk of the molten metal is the following elements:

Including at least one of, and the following conditions:

The method according to any one of claims 1 to 3. The method according to any one of claims 1 to 4, further comprising a step of atomizing the ESR melt in an atomizing chamber under an ESR furnace. The step of protecting the remelted ESR ingot with an inert gas, in vacuum, or with a slag covering the surface of the melt;
One of claims 1 to 4, further comprising a step of atomizing the remelted ESR ingot by discharging the liquid metal into the atomizing chamber through a drain at the bottom of the furnace containing the melt. The method described. A step of manufacturing a cold drawn wire by the method according to any one of claims 1 to 6.
A step of winding a spring from the cold drawn wire into a preferably spiral shape;
A method for producing a spring comprising the step of precipitation hardening the spring, preferably at a temperature of 450-500 ° C. for 0.5-2 hours.