JP6154780B2 - Two-phase stainless steel wire with excellent magnetic properties and magnetic wire mesh products using the same - Google Patents

Description

  The present invention relates to, for example, a duplex stainless steel wire excellent in magnetic properties with improved shape maintenance and corrosion resistance, and a magnetic wire mesh product using the same.

  In the food and pharmaceutical industries, separation / classification processing is carried out in which powders for raw materials are sieved using a wire mesh having a fixed mesh. For this reason, various wire mesh products for sieves or net conveyors according to usage patterns have been developed.

  For example, in a wire mesh for sieving, metal wires are plain or twilled so as to have a desired opening. Further, in a product for a net conveyor, a net-like long belt material is formed using a metal wire, and this is made into an endless annular shape and is used by being stretched between drive shafts.

  Conventionally, these wire mesh products have high strength and high strength such as SUS304 and SUS316 so that they do not have fatigue fracture due to impact or micro-vibration generated during the processing operation and satisfy friction and corrosion resistance with the powder to be processed. Corrosion resistant stainless steel wires have been employed.

  In recent years, even if a part of the metal mesh breaks and is mixed into the powder to be processed, the metal mesh is made of a ferromagnetic metal so that the broken fragments can be easily detected and removed by a magnetic separator, for example. It has been proposed to make with wire.

  As such a metal wire, the following Patent Document 1 is mass%, C: 0.01 to 0.05%, Si: 0.1 to 1.5%, Mn: 0.3 to 1.0%, A highly corrosion-resistant stainless steel wire is disclosed which is composed of Ni: 3 to 8%, Cr: 20 to 30%, Mo: 1.0 to 6.0%, and the balance consisting of Fe and inevitable impurities.

  Similarly, the following patent document 2 contains C ≦ 0.03%, Si: 2.0-5.0%, Ni: 5-8%, Cr: 15-20% as a magnetic wire mesh for sieving. A low-C, high-Si, two-phase stainless steel wire is disclosed.

  Furthermore, the following patent document 3 includes Ni: 2.5 to 8%, Cr: 18 to 30%, Mo: 3.5% or less, N: 0 to 0.2% for the net conveyor belt. And, a duplex stainless steel containing 0 to 1% in total of one or more of Cu, Ti and Nb, and Cr: 17% or more, Mo: 0 to 3%, C: 0.02% or less N: 0.02% or less, C + N: 0.05% or less, and proposed to use ferritic stainless steel containing 0 to 1% in total of one or more of Cu, Ti and Nb doing.

Japanese Patent Laid-Open No. 10-130788 JP 2004-332109 A JP 2002-120919 A

  Wire meshes used in the food and pharmaceutical industries are required to have sufficient magnetic properties, additional fatigue rupture resistance, and durability over time that does not change the mesh size even during long-term use. Furthermore, even when the wire mesh is washed with a strong chemical solution such as caustic soda, it is required to have corrosion resistance and magnetic characteristics that can sufficiently withstand this.

  The present invention has been devised in view of the above problems, and for a magnetic wire mesh, a duplex stainless steel excellent in magnetic properties capable of exhibiting excellent durability while improving weaving workability. The main purpose is to provide a wire and a magnetic wire mesh product using the wire.

The present invention is a two-phase stainless steel wire excellent in magnetic properties having a crystal structure of austenite phase and ferrite phase,
In mass%, C: 0.001 to 0.06%, Si: 0.02 to 1.0%, Mn: 0.05 to 2.0%, Ni: 5.0 to 8.0%, Cr: 20.0 to 28.0%, Mo: 1.0 to 5.0%, and 0.08 to 0.35% N, the balance consists of Fe and inevitable impurities,
The steel wire has a tensile strength of 800 to 1150 MPa and an elongation of 15% or more,
The characteristic value X according to the following formula (1) is 0.50 or less.
Characteristic value X = {Elongation (%) / √Equivalent wire diameter (mm)} / Strength ratio (%) (1)
However, the yield strength ratio (%) is a ratio (%) obtained by dividing 0.2% yield strength (MPa) in the tensile test of the steel wire by the tensile strength (MPa).

  In the stainless steel wire of the present invention, the yield strength ratio is desirably 75% or more.

In the stainless steel wire of the present invention, it is desirable that the Ni equivalent defined by the following formula (2) is 1.8 to 4.0 times the Cr equivalent defined by the following formula (3).
Ni equivalent = Ni + 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si +
12.6 (C + N) (2)
Cr equivalent = Cr + 4Si-22C-0.5Mn-1.5Ni-30N (3)

  In the stainless steel wire of the present invention, it is desirable that the austenite phase has an average particle size of 0.2 to 8 μm and is distributed in an area ratio of 40 to 60% along the longitudinal direction of the stainless steel wire.

In the stainless steel wire of the present invention, the pitting corrosion index (PRE) defined by the following formula (4) is preferably 30 to 45.
Pitting corrosion index (PRE) = Cr + 3.3Mo + 16N (4)

  In the stainless steel wire of the present invention, the surface roughness Rz is preferably 0.1 to 2.5 μm.

  In the stainless steel wire of the present invention, in addition to the above composition, Nb: 0.05-0.25%, Cu: 0.1-0.5%, Ti: 0.1-0. It is also desirable to contain 5% of any one element or two or more elements.

  The stainless steel wire of the present invention is preferably used as a mesh body for applications utilizing magnetic properties, for example, for a sieve that is woven into a mesh network body using the stainless steel wire of the present invention as a meridian or parallel. Alternatively, it can be used as a magnetic wire mesh product for a net conveyor.

  The stainless steel wire of the present invention is preferably used as a net for applications utilizing magnetic properties. For example, the stainless steel wire of the present invention is formed by continuously forming a molded body bent in a spiral shape or a crimp shape. It can be used as a magnetic wire mesh product for a sieve or a net conveyor formed by being joined to each other.

  The stainless steel wire of the present invention is in mass%, C: 0.01 to 0.06%, Si: 0.02 to 1.0%, Mn: 0.05 to 2.0%, Ni: 5.0 -8.0%, Cr: 20.0-28%, Mo: 1.0-5.0%, and 0.08-0.35% N, with the balance being composed of Fe and inevitable impurities Stainless steel wire.

  Since the stainless steel wire of the present invention has a two-phase crystal structure of an austenite phase and a ferrite phase, it can satisfy magnetic properties and mechanical properties optimal for weaving. When such a stainless steel wire is woven as a wire mesh, the mesh opening associated with use (hereinafter sometimes simply referred to as mesh opening) is suppressed over a long period of time. In addition, the stainless steel wire of the present invention is excellent in wear resistance and provides good durability. Furthermore, the stainless steel wire of the present invention can sufficiently withstand, for example, an alkaline cleaning solution due to excellent corrosion resistance, and can be particularly preferably used as a material for a magnetic wire mesh for pharmaceuticals and foods.

  The stainless steel wire of the present invention has a tensile strength of 800 to 1150 MPa and an elongation of 15% or more, and the characteristic value X indicated by the relationship between the elongation (%) and the proof stress ratio (%) of the steel wire is It is set to 0.50 or less. Such a stainless steel wire exhibits, for example, a substantially constant stress until it breaks beyond the elastic region during processing. Therefore, it is useful to provide a magnetic wire mesh with less processing variation. In addition, the wire mesh product made of the stainless steel wire of the present invention can provide excellent flatness by preventing undulation deformation and the like, and can prevent the opening for a long period of time.

  As described above, the stainless steel wire of the present invention can be widely applied as wire mesh products for sieves or net conveyors, particularly those suitable for magnetic wire mesh applications utilizing magnetic properties.

It is a stress-strain diagram in the tensile test of the stainless steel wire of one Embodiment of this invention. It is a graph which shows the relationship between the pitting corrosion index (PRE) and the pitting corrosion critical temperature (CPT) of the stainless steel wire based on implementation of one Embodiment of this invention. It is a top view of the net body for net conveyors using the stainless steel wire which shows one Embodiment of this invention. (A) is a top view of the sieve mesh used for isolation | separation and classification, (B) is the AA sectional drawing. It is a microscope picture which shows the crystal structure of the longitudinal cross-section of the stainless steel wire of one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In one embodiment of the present invention, a two-phase stainless steel wire having a crystal structure of an austenite phase and a ferrite phase and having excellent magnetic properties is provided.

  The austenitic phase increases the pitting corrosion index of the surface of the stainless steel wire. This improves the corrosion resistance to various cleaning solutions and powders to be processed. The austenite phase also improves the strength of the stainless steel wire. This enhances the stability of the shape during, for example, wire mesh weaving. On the other hand, the ferrite phase imparts ferromagnetic properties to the stainless steel wire. For example, even when a part of the stainless steel wire having magnetic properties is mixed in the powder to be treated, it can be easily removed from the powder by magnetic adsorption.

  As a preferable aspect, the stainless steel wire of the present embodiment has, for example, 30 to 70 vol%, preferably 40 to 60 vol% of austenite phase 30, and the remainder is a double layer of ferrite phase 40 as seen in FIG. 5. Contains mixed tissue.

  The stainless steel wire of the present embodiment is, as a chemical component, in mass%, C: 0.001 to 0.06%, Si: 0.02 to 1.0%, Mn: 0.05 to 2.0%, Ni: 5.0 to 8.0%, Cr: 20.0 to 28.0%, Mo: 1.0 to 5.0%, and 0.08 to 0.35% N, the balance being It consists of Fe and inevitable impurities. The reason for limiting the component range of each constituent element is as follows.

  C: C (carbon) can increase the strength of steel, but tends to reduce the corrosion resistance by forming carbides and the like. Further, since C is a strong austenite-forming element, if it is contained in a large amount, it may be stable in the austenite state and it may be difficult to obtain predetermined magnetism. Therefore, C is 0.001 to 0.06%, more preferably 0.03% or less.

  Si: Si (silicon) is a strong ferrite-forming element, and is effective for imparting magnetism to the steel wire. On the other hand, a large amount of Si may reduce the toughness of the material. Therefore, Si is 0.02 to 1.0%, more preferably 0.3 to 0.8%.

  Mn: Since Mn (manganese) is an austenite-forming element, it is effective in stabilizing austenite and improving corrosion resistance and lowering the transformation point. On the other hand, Mn may accelerate work hardening at the same time and bring about higher strength than necessary. Therefore, Mn is set to 0.05 to 2.0%, more preferably 0.5 to 1.7%.

  Ni: Ni (nickel) is also an austenite-forming element like Mn, and in particular, 5.0% or more of addition is necessary to provide corrosion resistance that can withstand alkaline solutions. However, since Ni is expensive and promotes work hardening, it is desirably 5.0 to 8.0%, and more preferably 5.7 to 7.5%.

  Cr: Cr (chromium) is effective because it stabilizes the ferrite for improving the magnetic properties, greatly affects the pitting corrosion index (PRE), and increases the corrosion resistance in an alkaline solution. Therefore, it is necessary to add at least 20.0%. However, if it exceeds 28.0%, the hot workability deteriorates and the balance as a duplex stainless steel is lost. More preferably, Cr is 24.0% or more. A more preferable range of the upper limit is set to 26.0%.

  Mo: Mo (molybdenum) is made 1.0 to 5.0%, preferably 1.5% or more, more preferably 2.8% or more in order to improve the corrosion resistance of the material while reducing the cost. Is set.

  N: N (nitrogen) is an austenite stabilizing element, like C, and contributes to increasing the strength and improving the corrosion resistance by making the crystal grains of austenite fine. On the other hand, a large amount of N may reduce the workability of the material. Therefore, N is 0.08 to 0.35%, more preferably 0.15 to 0.32%, and still more preferably 0.20 to 0.32%.

  In addition, N is particularly effective when 2C + N is 0.40% or less, more preferably 0.36% or less, in relation to C.

Furthermore, with respect to the above chemical components, in a preferred embodiment of the stainless steel wire, the Ni equivalent defined by the following formula (2) is adjusted to 1.8 to 4.0 times the Cr equivalent defined by the following formula (3). Is done. By setting the Ni equivalent to 1.8 to 4.0 times the Cr equivalent, the wear resistance of the stainless steel wire is significantly improved. More preferably, it is adjusted to 2.2 to 3.8 times.
Ni equivalent = Ni + 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si +
12.6 (C + N) (2)
Cr equivalent = Cr + 4Si-22C-0.5Mn-1.5Ni-30N (3)

  The Ni equivalent in the stainless steel wire of the present invention is, for example, 22 to 33%, preferably 24 to 30%. Similarly, the Cr equivalent is, for example, 5 to 15%, preferably 8 to 12%.

With respect to the chemical component, in a more preferable embodiment of the stainless steel wire, the pitting corrosion index (PRE) defined by the following formula (4) is adjusted to 30 to 45. The pitting corrosion index (PRE) indicates pitting corrosion resistance, and the higher this value, the better the corrosion resistance. A stainless steel wire having such a pitting corrosion index (PRE) can drastically improve the corrosion resistance against an alkaline highly corrosive solution used for a cleaning liquid or the like, and can further improve the occurrence of pitting corrosion.
Pitting corrosion index (PRE) = Cr + 3.3Mo + 16N (4)

  In particular, as the basic composition, C ≦ 0.03%, Si ≦ 0.80, Mn ≦ 1.3%, Ni: 6.0 to 8.0%, Cr: 24.0 to 26.0%, Mo : Stainless steel wire containing 3.0 to 5.0%, N: 0.22 to 0.35% and having a pitting corrosion index PRE of 38 or more improves strength, corrosion resistance, and pitting corrosion resistance It is the best one. In a more preferred embodiment, the pitting corrosion index PRE is set in the range of 40 to 43.

  The stainless steel wire of the present embodiment has a tensile strength of 800 to 1150 MPa and an elongation of 15% or more as mechanical characteristics, and is shown by the relationship between the elongation (%) and the proof stress ratio (%). The characteristic value X of the following equation (1) is adjusted to be 0.50 or less.

      Characteristic value X = {Elongation (%) / √Equivalent wire diameter (mm)} ÷ Strength ratio (%) (1)

Here, the elongation means the elongation at break corresponding to the elongation rate until breakage due to tension, and is expressed, for example, as a percentage (%) obtained by dividing the permanent elongation amount of the gauge distance after fracture by the original gauge distance. It is. The yield strength ratio is defined as a ratio (%) obtained by dividing the yield strength of the steel wire by the tensile strength (MPa). Furthermore, yield strength is defined as the stress when 0.2% permanent set remains. Each mechanical characteristic of these stainless steel wires can be measured by, for example, a tensile test method according to JIS-Z2241. For more accurate measurement, it is recommended to use a strain gauge and extensometer, for example.

  It has been pointed out that stainless steel wires usually have different mechanical properties depending on the finished wire diameter. That is, even if it is a stainless steel wire having the same composition, the mechanical characteristics (in the case of a very fine wire whose finished dimensions are extremely fine, and conversely in the case of a wire having a thick wire diameter of several millimeters) For example, the elongation and tensile strength) are not the same, and the thinner the wire diameter, the higher the strength and the lower the elongation rate.

From the viewpoint of adjusting such a wire diameter effect, in the present invention, the one obtained by dividing the elongation of the steel wire by the wire diameter element in the above formula (1) is used. In this case, the stainless steel wire includes those whose cross-sectional shape is a non-circular shape. Therefore, as a wire diameter element, the wire diameter of a perfect circular cross-section having a cross-sectional area equal to the cross-sectional area of the steel wire, that is, equivalent. Wire diameter is used.

  The stainless steel wire has the advantage that the smaller the tensile strength, the smaller the pitch (woven mesh pitch) when making the wire mesh, and the easier it is to weave. However, when the tensile strength of the stainless steel wire is less than 800 MPa, the rigidity is inferior, and unnecessarily plastic deformation or disconnection is likely to occur. In addition, the woven wire mesh is easy to open, and there is a possibility that the service life may be shortened.

  On the other hand, when the tensile strength of the stainless steel wire exceeds 1150 MPa, the strength is too high, and after processing into a wire mesh, the opening becomes large due to the effect of springback or the like, and the finished state such as undulation is stabilized. There is a tendency to become difficult. Moreover, since the fatigue strength of the stainless steel wire is reduced, there is a risk of breakage. In a particularly preferred embodiment, the tensile strength of the stainless steel wire is 850 MPa or more and 1100 MPa or less.

  The stainless steel wire of the present embodiment has a relatively large elongation of 15% or more. Such a stainless steel wire exhibits good workability when processed into a wire mesh and can be processed with less energy. When the elongation of the stainless steel wire is less than 15%, for example, it is not suitable for a net product subjected to a large bending deformation. The elongation of the stainless steel wire is preferably 20% or more, more preferably 22 to 40%.

  Furthermore, in the stainless steel wire of the present embodiment, the characteristic value X obtained by dividing the elongation (%) by the formula (4) by the yield strength ratio (%) and the equivalent wire diameter (mm) is adjusted to 0.50 or less. ing.

FIG. 1 shows a stress-strain diagram in a tensile test of the stainless steel wires (steel wires A1, A4, B1 and B4) of the present embodiment, and the characteristic value X is as follows.
A1: 0.351
A4: 0.298
B1: 1.396
B4: 0.514
The steel wires A1 and A4 correspond to this embodiment in which X is set to 0.50 or less (Example material), and the steel wires B1 and B4 have X greater than 0.50. It is set (comparative material). Further, the stainless steel wires A1 and A4 according to the present invention both have a proof stress ratio of 75% or more, and in an example, 85% to nearly 90%. On the other hand, although the yield strength ratio of the comparative example material is slightly high in B4, no material exceeding 80% is seen.

  As is apparent from FIG. 1, the stainless steel wires A1 and A4 according to the present embodiment exhibit, for example, a substantially constant stress or a stress that is slightly increased until it breaks beyond the elastic region. A stainless steel wire having such characteristics is useful for providing a good wire mesh that is not easily affected by variations during processing and has excellent uniformity. In addition, the wire mesh made of each stainless steel wire of this embodiment can provide excellent flatness by preventing wave deformation and the like, and can prevent the opening for a long time.

  In this way, when the characteristic value X is relatively small at 0.50 or less, the change after the apparent yield point indicated by the relationship between the stress and the strain is almost linear within a certain strain amount range. On the other hand, it is considered that a characteristic value X higher than that exhibits a parabolic curve having a relatively high rate of change around the yield point, which is a variation factor of the variation.

For this reason, for example, in the case where the proof stress ratio is relatively small and has a certain tensile strength like the comparative example material, the slope of the stress change after the elastic limit becomes large. In order to stabilize the inclination, a relatively large amount of elongation corresponding to that is necessary. However, in the case of containing N as in the duplex stainless steel wire according to the present invention, the maximum amount of elongation is substantially 40. However, it is difficult to obtain anything exceeding this. Therefore, since the rate of change (inclination) is difficult to reduce, for example, even a slight difference in applied tension during processing has a large effect. In other words, in the actual weaving process, the tension and displacement applied to the steel wire differ from part to part, and are not all constant. In order to determine the stabilization of the molded shape when processing, it is preferable that the rate of change in the plastic region is as small as possible. From this point of view, it is desirable that the characteristic value X of the yield strength ratio and the elongation amount is in the predetermined range.

  In order to further enhance the above effect, the characteristic value X of the stainless steel wire is more preferably 0.42 or less, and further preferably 0.38 or less. The lower limit value of the characteristic value X is not particularly limited, but if it is too small, the elongation is less than necessary, which may affect the workability in the weaving process. For this reason, the characteristic value X is set to 0.10 or more, for example.

The stainless steel wire of this embodiment is manufactured through a final solution heat treatment at a temperature in the range of 900 to 1200 ° C. that satisfies the following formula (5), for example, and is rapidly cooled after heating.
6000 ≦ {T × t × 1 / d} × {1−√ (2C + N)} ≦ 9500 (5)
Here, the symbols are as follows.
T: Heating temperature (° C)
t: Heating time (sec.)
d: Equivalent wire diameter of stainless steel wire (mm)
C, N: Mass of C and N contained in stainless steel wire (wt%)

  In the production process of the stainless steel wire of the present embodiment, for example, the wire diameter is adjusted to a predetermined wire diameter by repeatedly performing drawing processing such as cold wire drawing and rolling at a predetermined processing rate and solution heat treatment as appropriate. The diameter is reduced. Thereafter, a bright heat treatment that satisfies the condition of the formula (5) is finally performed. The final drawing process is desirably performed by wet processing using, for example, a diamond die so as to have a bright finish, and the processing rate is, for example, 50% to 95%, preferably 60% to 85%. % Is set.

  The stainless steel wire of this embodiment preferably has a surface roughness Rz of 0.1 to 2.5 μm by the above-described chemical components and a predetermined bright finish. If the surface is rougher than necessary, weaving workability will be reduced, and conversely if it is made super bright finish such as less than 0.1 μm, the cost will be increased in terms of small diameter workability and processing yield of the stainless steel wire itself. Become. Moreover, such a smooth surface can further improve corrosion resistance and fatigue resistance, More preferably, it is 0.3-2.0 micrometer Rz.

  The stainless steel wire of the present embodiment preferably has a magnetic permeability of 30 to 70 (H / m) as a magnetic property. The magnetic permeability indicates the degree to which the material is magnetized by affecting the surrounding magnetic field. In the field of stainless steel wire, the strength level of the magnetic permeability is regarded as ferromagnetic. The measurement of the magnetic permeability can be performed by, for example, a direct current magnetization measuring apparatus, and is also found in JIS-C2501. The larger the value of the magnetic permeability, the more ferromagnetic it is. Usually, when a magnetic field of strength H is applied to the material, and the magnetic flux density generated by magnetizing the magnetic material is B, the magnetic permeability μ is obtained by B / H. Thereby, even if a part of the stainless steel wire breaks during the use process and is mixed into the powder to be treated, it can be easily taken out by magnetic adsorption.

  FIG. 5 is an example of a photomicrograph showing a magnified arbitrary vertical cross section of a stainless steel wire, the structure of which is appropriately adjusted according to the component composition and processing conditions (especially heat treatment conditions). It has a mixed structure of the austenite phase 30 extending in the longitudinal axis direction and the ferrite phase 40, and the austenite phase 30 has an average particle diameter of, for example, 0.2 to 8 μm, and extends along the longitudinal direction of the steel wire. Are distributed in a row. The more preferable area ratio has a range of 40 to 60%.

  The average particle diameter and the area ratio are determined by, for example, microscopic observation in which an arbitrary cross section of the stainless steel wire is magnified about 100 to 400 times. For the measurement, for example, for a plurality of arbitrary austenite grains confirmed in the cross section of the steel wire, a double average method is recommended in which the maximum diameter and the minimum diameter are averaged and averaged by the number of measurements. . Not limited to this, for example, it can be obtained from a longitudinal section as shown in FIG. In that case, it can also be obtained by extracting a plurality of austenite grains extending in the longitudinal direction and having a maximum particle size (α) of about the top 5 to 10 and averaging them. The reason why the number of extraction points is set to the top five is that each austenite grain found in the measurement field of view does not pass through the central axis, but may show only a part of the peripheral part, for example. By excluding.

  The stainless steel wire of this embodiment can be woven and processed in the same manner as SUS304 conventionally used and the network according to Patent Document 3, and the characteristic value X is made 0.50 or less by adding N in particular. This suppresses quality variations and improves resistance to fatigue and wear. The addition of N not only refines the crystal grains, but also increases the pitting corrosion index (PRE) and contributes to the improvement of corrosion resistance.

Therefore, the net conveyor using the stainless steel wire of this embodiment and the wire mesh for the sieve used for separation / classification have a reduced shape due to damage and wear due to fatigue compared to conventional ones, and a stable shape. As a result, long-term use is possible. This contributes to improvement of production efficiency and reduction of running costs.

  The stainless steel wire of this embodiment is particularly excellent in corrosion resistance against sodium hydroxide as compared with Patent Document 2 described above. For this reason, for example, it is used as a net body for a net conveyor device that is endlessly spread between rollers, or for a process of roasting or dissolving and removing powder to be treated at the time of washing, or conventionally. It can be widely used as a separation / classification network.

  FIG. 3 shows a partial plan view of the wire mesh product 1 using the stainless steel wire of the present embodiment. The wire net product 1 is made, for example, as a net body 1A for a net conveyor. 1 A of net | network bodies are comprised with the forming wire body 11 ... which the stainless steel wire 10 of this embodiment was plastic-processed, for example in the shape of a flat spiral, and the connecting wire 12 which connects these continuously. Not limited to such a spiral molded product, it can also be used as a product bent into a crank shape, for example.

The formed wire body 11 is stretched at a predetermined pitch so as to substantially form a mesh size, and an upper connection portion 11c and a lower connection portion 11d are provided on both upper and lower sides of the forming wire body 11 so that the connecting wire 12 is connected to each other. It is done. The connecting wire 12 is a wire having the same diameter or a different thickness as the shaped wire 11 and is corrugated corresponding to the winding pitch of the shaped wire 11. The stainless steel wire 10 of this embodiment can be used for these shaped wire 11 and / or connecting wire 12.

  As another form of the wire mesh product 1, FIG. 4 (A) shows a wire mesh 1B for a sieve in which meridians 21 and latitudes 22 are woven at a predetermined pitch. The stainless steel wire 10 of this embodiment can be used for these meridian lines 21 and / or latitude lines 22. In addition, the code | symbol 23 is a guard part provided along the both sides of the metal-mesh 1B so that FIG.4 (B) which is AA cross section of FIG.4 (A) may be seen. The guard portion 23 is formed by encapsulating the wire mesh 1B with a metal sheet 23a, and is formed in, for example, a long shape or a disk shape.

  The structure of the wire mesh product in which the stainless steel wire of the present embodiment is used is not particularly limited to the above-described specific mode. For example, twill weave, tatami mat, knitted fabric, crimp weave (crimping on steel wire) And a wire mesh formed by fitting the corrugated shaped wire bodies together. Further, for example, various forms of nets can be adopted for the belt of the net conveyor. In the woven net body, it is desirable to adjust the opening to about 5 to 300 mesh, for example.

  The wire diameter of the stainless steel thin wire 10 of the present embodiment is not particularly limited, and can be appropriately set according to the application and purpose. For example, as a sieving wire mesh for separation / classification in food and pharmaceutical processing processes, the equivalent wire diameter is, for example, 0.01 to 5 mm, more preferably 0.1 depending on the particle size of the powder to be processed. About 3 mm is desirable. As for the cross-sectional shape of the stainless steel wire, various shapes such as a round wire or an elliptical wire having a general circular cross section, a rolled strip, and a triangular cross-section are used.

In another embodiment of the present invention, the stainless steel wire can contain any one or more of the following third elements as a chemical component in mass%.
(A) Nb: 0.05 to 0.25%
(B) Cu: 0.1 to 0.5%
(C) Ti: 0.1 to 0.5%

  Nb improves the cold strength of the steel wire and expands its range of use, but there is a risk of reducing hot workability. Therefore, although it is determined in the range of 0.05 to 0.25%, the blending amount is preferably 0.08 to 0.20%, and more preferably 0.10 to 0.18%.

  Cu makes the corrosion potential noble and can provide improved corrosion resistance, reduced pitting susceptibility, and good cold workability. On the other hand, since the addition of a large amount of Cu may reduce the material strength, it is set within the above range. Cu is more preferably 0.1 to 0.30%.

  Ti contributes to improvement of wear resistance by fine precipitation. However, the addition of a large amount of Ti may generate a Ti compound and impair the weaving processability. Therefore, Ti is more preferably 0.1 to 0.3%.

  As mentioned above, although embodiment of this invention was described in detail, it cannot be overemphasized that this invention is not limited to the said specific embodiment, and can be implemented in various aspects other than these embodiment. .

[Example 1]
In order to confirm the effect of the present invention, a plurality of types of duplex stainless steel wires (raw material wires) having chemical components shown in Table 1 were prepared as examples. Each steel wire was obtained by reducing the diameter to 0.6 mm while repeating cold wire drawing and heat treatment at a processing rate of 60 to 85%. Next, this fine wire was heat-treated while adjusting the heating temperature and the heating time, and soft stainless steel wires (A1 to A3) were produced as prototypes. Moreover, as a comparative example, SUS304 (comparative material B1), SUS316 (comparative material B2), and another company's duplex stainless steel wire, high Mn (comparative material B3) and the high Si duplex described in Patent Document 2 above. Stainless steel wires (comparative materials B4 and B5) and the like were used.

  The final wire drawing of this stainless steel wire is based on wet wire drawing with a processing rate of 75%. A diamond die is used as the processing die, and the lubricating oil has a melt viscosity of 50 to 50 at room temperature. 80 non-chlorine drawing oils were used. By this processing, the surface roughness Rz of the line was improved to 0.3 to 0.7 μm.

The stainless steel wire after the final drawing is then subjected to the equation (5) in the range of heating temperature: 1000 to 1100 ° C., time: 10 to 60 sec, and the wire diameter and the amounts of C and N are related. The solution heat treatment was performed within the range of 6300 to 7200 to be satisfied, and the crystal structure, mechanical properties, and other material properties of each obtained steel wire were investigated. The results are shown in Table 2. In addition, the heating atmosphere of heat processing was performed by AX gas with a dew point of -30 degreeC.

  In order to verify the effects of the present invention from various aspects, sample No. Example materials A4 to A8 and comparative example materials B4 and B5 were added, and the effects of the composition and the finished wire diameter were also confirmed. As a manufacturing condition, for a fine wire having a finished wire diameter of 1.2 mm or more, a dry wire drawing method using an alloy die is adopted.

Each of the examples belonging to the present invention had a tensile strength of about 900 to 1150 MPa, a high yield strength ratio, and a large elongation characteristic of 15 to 35%. The characteristic value X calculated by the elongation and yield strength ratio obtained from these characteristics both satisfied 0.50 or less. The tensile test was performed based on the JIS standard with a gauge distance of 100 mm.

  On the other hand, SUS304 and SUS316 of Comparative Examples B1 and B2 have large elongation characteristics but low strength characteristics, a yield strength ratio of approximately 50%, and the X value of 1.3 or more. Further, as in the present invention, Comparative Examples B3 to B5 using duplex stainless steel were processed at a high temperature or for a long time while changing the wire drawing rate and heating conditions, and the X values were all 0. More than .50 and nearly 0.6.

Further, as a result of microscopic observation of the longitudinal section of each example material enlarged 400 times, the austenite phase had an average particle diameter α of 2 to 6 μm and continued in the longitudinal direction, and the area ratio was 45 to 54%. It was. Similarly, the average particle diameter α of the two-phase comparative example material was 5 to 10 μm, and the area ratio was 47 to 55%.
[Example 2]

  Next, a 14-mesh plain woven wire mesh was produced by weaving using each of the above 0.6 mm steel wires, and the following characteristics were tested. The evaluations are shown in the order of S, A, B, C from good to bad.

<Weaving processability, mesh accuracy>
Weaving workability and mesh accuracy are related to the appropriateness as the mesh mesh, and are evaluated for the presence or absence of wire breakage or stretched wire and the variation in mesh accuracy associated with processing. The notation “S” and “A” Indicates that it can be used without any problem, and “B” and “C” indicate that they are determined not to be suitable for the network of the present invention involving vibration.

<Flatness of wire mesh, corrugation of mesh ear>
The flatness is a relative evaluation of the size of the wire mesh roll when a rolled wire mesh (width 1 m) is drawn and spread on the floor. The waviness of the ear portion indicates the presence or absence of waviness on both sides of the net, and the evaluations “S” and “A” indicate that the maximum value of the rising dimension is within 5 mm as a non-defective product.

<Corrosion resistance>
With respect to each net product obtained in this example, each (30 × 30 mm) corrosion resistance test sample was collected, and the corrosion resistance was measured based on JIS-G0578 (a ferric chloride corrosion test method for stainless steel). Tested. The corrosive solution is a mixture solution of 6% FeCl ₃ + 1 / 20N HCl, and is accompanied by corrosion by immersing each measurement sample in each test solution heated in the range of 20 ° C. to 80 ° C. for a predetermined time. Evaluation is based on the ratio (%) obtained by dividing the weight loss by the mass before the test. The corrosion holding time was 24 hours.

<Pitting corrosion index>
The pitting corrosion index was measured according to JIS-G0577 (stainless steel pitting corrosion potential measuring method) using a sodium chloride aqueous solution having a predetermined concentration of 30 ° C. as a test solution under the following test conditions. A higher pitting corrosion potential means that pitting corrosion is less likely to occur.
・ Sample size Surface area 100mm ²
・ Potential sweep speed 20mv ・ min ^-1
・ Anode current density 1000A ・ cm ^-2
・ Degassing gas Argon gas (180ml / min.)

<Fatigue resistance>
Fatigue resistance was evaluated based on the number of times of bending to break when each stainless steel wire used in the net product was repeatedly bent at 90 degrees with a radius of curvature equivalent to 10 times the wire diameter r. It is. Evaluation shows that the bending angle is 90 degrees once, “A” is 30 times or more, “B” is less than 10 to 30 times, and “C” is less than 10 times. Since the comparative material B1 has a relatively high work hardening rate, it was a relatively small number of times, but no other problems were observed.

<Magnetic properties>
A portion (about 2 g) of a stainless steel wire constituting the net product was sampled, and this was used as a test piece to evaluate the magnitude of the magnetized separation distance when a neodymium magnet was gradually approached. . In addition, the sense of rigidity is an evaluation of the strength of the waist of a net product by touch.

  The results of the test are shown in Table 3.

表３のテスト結果に示されるように、本発明に係る各実施例材は、比較材に比して、いずれも良好であった。

As shown in the test results of Table 3, each of the example materials according to the present invention was better than the comparative material.

FIG. 2 shows the relationship between the pitting corrosion index (PRE) and the critical temperature (CPT) at which pitting corrosion occurs, and it can be seen that it changes proportionally with a certain slope. The area on the right side of the broken line indicates the anticorrosion stable area. All of the materials of this example have a pitting index of 30 to 42, and for example, it can be estimated that they can be used without pitting even in a heating environment at a temperature of 60 ° C. or higher.

[Example 3]
As another example, here, in the processing stage of Example 1, a part of the stainless steel wires of Samples A2 and A4, which have been reduced to 1.4 mmφ, are extracted and each has a thickness of 0.6 × width. Cold rolled into a 1.5 mm strip. The final heat treatment was performed in a temperature annealing range of 1030 to 1060 ° C. × 10 to 60 sec. In the same condition range as in Example 1 by a strand annealing furnace in an N atmosphere.

  About each obtained strip | belt material, the tensile strength, yield strength, elongation, crystal structure, and magnetic characteristic were investigated similarly to the said Example 1. FIG. A part of the results are shown in Table 4. In both cases, the characteristic value X was 0.30 and 0.28, and both the tensile strength and the elongation met the requirements of the present invention.

  Next, the strip was cut into a length of 800 mm and bent into a crank shape with a bending radius of 2 mm under a load tension of 200 N. The shape was not significantly different from that of Example 1, and the variation in the shape of the springback angle was stable at 3σ = 0.8.

1A network 1B wire mesh
10 Stainless steel wire 11A, 11B Formed wire body 21 Vertical line

Claims (9)

A duplex stainless steel wire with austenite and ferrite phase crystal structure and excellent magnetic properties,
In mass%, C: 0.001 to 0.06%, Si: 0.02 to 1.0%, Mn: 0.05 to 2.0%, Ni: 5.0 to 8.0%, Cr: 20.0 to 28.0%, Mo: 1.0 to 5.0%, and 0.08 to 0.35% N, the balance consists of Fe and inevitable impurities,
The steel wire has a tensile strength of 800 to 1150 MPa and an elongation of 15% or more,
A stainless steel wire for a magnetic wire mesh, wherein a characteristic value X according to the following formula (1) is 0.50 or less.
Characteristic value X = {Elongation (%) / √Equivalent wire diameter (mm)} / Strength ratio (%) (1)
However, the yield strength ratio (%) is a ratio (%) obtained by dividing 0.2% yield strength (MPa) in the tensile test of the steel wire by the tensile strength (MPa).   The stainless steel wire according to claim 1, wherein the yield strength ratio is 75% or more. The stainless steel wire according to claim 1 or 2, wherein the Ni equivalent defined by the following formula (2) is 1.8 to 4.0 times the Cr equivalent defined by the following formula (3).
Ni equivalent = Ni + 0.65Cr + 0.98Mo + 1.05Mn + 0.35Si + 12.6 (C + N) (2)
Cr equivalent = Cr + 4Si-22C-0.5Mn-1.5Ni-30N (3)   The austenite phase has an average particle diameter of 0.2 to 8 µm and is distributed at an area ratio of 40 to 60% along the longitudinal direction of the stainless steel wire. Stainless steel wire. The stainless steel wire according to any one of claims 1 to 4, wherein the pitting corrosion index (PRE) defined by the following formula (4) is 30 to 45.
Pitting corrosion index (PRE) = Cr + 3.3Mo + 16N (4)   The stainless steel wire according to claim 5, wherein the surface roughness Rz is 0.1 to 2.5 μm.   In addition to the above composition, Nb: 0.05 to 0.25%, Cu: 0.1 to 0.5%, Ti: 0.1 to 0.5% in terms of mass%, or 2 The stainless steel wire according to any one of claims 4 to 6, comprising at least a third element.   A mesh body for use utilizing magnetic characteristics, wherein the stainless steel wire according to any one of claims 1 to 7 is used as a meridian or a latitude line for a sieve or a net conveyor woven into a mesh mesh body. Magnetic wire mesh products. A mesh body for use utilizing magnetic properties, wherein the stainless steel wire according to any one of claims 1 to 7 continuously joins a molded body bent in a spiral shape or a crimp shape, or Magnetic wire mesh products for sieves or net conveyors formed by fitting.

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