JP4624774B2 - Cr-based stainless steel wire rod for wear resistance excellent in corrosion resistance and cold workability, or lead wire for loom cages using the steel wire - Google Patents

Description

  The present invention relates to a Cr-based stainless steel wire excellent in wear resistance and corrosion resistance, and is suitable as, for example, a lead material for a shaft or a miniature rope, for example, a weaving machine, especially in cold working or cutting. The present invention relates to an inexpensive stainless steel wire or steel wire having excellent wear resistance and corrosion resistance, and a lead material for a loom cage made of the steel wire.

  Up to now, for machine parts that require wear resistance and corrosion resistance, annealed SUS420J2 and SUS440C and other martensitic stainless steels are cold formed and cut into parts, and then hardened and used. (For example, Patent Document 1).

  Further, when high corrosion resistance is required in martensitic stainless steel, alloy elements such as Mo and N have been added. Thus, in recent years, martensitic stainless steel having excellent corrosion resistance and good cold workability has been developed (Patent Document 2).

  However, since martensitic stainless steel requires quenching and tempering heat treatment after cold working, the integrated manufacturing cost of parts increases. Therefore, in parts that require corrosion resistance and wear resistance, ferritic stainless steel or austenitic stainless steel, which is advantageous in corrosion resistance but inferior in wear resistance, is used in the cold working state, and parts are frequently replaced. Have responded by doing.

  On the other hand, in stainless steel miniature ropes centering on SUS304, in addition to cold workability (strength) and corrosion resistance, improvement in wearability is also required.

  Among such needs, recently, wear resistant steel in which carbide is dispersed in austenitic stainless steel has been proposed (Patent Document 3). However, austenitic stainless steel has a poor thermal conductivity, and there is a problem that the wear resistance deteriorates at a site where frictional heat is generated.

  Therefore, wear-resistant steel in which Nb and Ti-based carbides are dispersed in Cr-based stainless steel having high thermal conductivity has also been proposed (Patent Documents 4 and 5).

  Furthermore, a wear-resistant steel in which Nb, Ti, V, Zr, and W are dispersed in a ferrite and martensite structure using a Cr-based stainless steel has also been proposed (Patent Document 6).

  Further, C: 0.07 to 0.35%, Si: 1.0% or less, Mn: 1.0% or less, Cr: 10 to 17%, Mo: 0.5 to 3.0%, N: 0 A lead material for a loom sheath made of martensitic stainless steel containing 0.05 to 0.20% has also been proposed. (Patent Document 7)

JP 2001-271142 A JP-A-10-36945 JP 2003-147493 A JP 2002-235113 A JP 2000-192198 A Japanese Patent Laid-Open No. 2002-220640 JP 2004-225085 A

  By the way, in general, Cr-based stainless steel is inexpensive and has a large thermal expansion coefficient as compared with Ni-based materials. It is difficult to satisfy all of the cold workability, wear resistance, and corrosion resistance in the Cr-based stainless steel made by JIS. For example, in the stainless steel according to Patent Document 7 for a lead material for loom sheaths, carbide is consciously increased as a means for increasing wear resistance. For this reason, 0.17 to 0.29% in the embodiment. Although it is decided to contain a large amount of C, the pitting corrosion potential (vs Ag / AgCl) showing the corrosion resistance in that case is shown to be a result of staying at 40 to 150 mV.

  Therefore, for example, when using a thread coated with titanium oxide (UV-treated thread) to cut off ultraviolet rays, it is sometimes used as a lead material when it reacts with an oil agent or the like that is sometimes given or is stored for a long time after work Is often not sufficient in terms of corrosion resistance, such as cracking, and it is difficult to say that it has sufficient corrosion resistance, wear resistance to withstand strong wear, and excellent workability. Improvement is desired.

  Accordingly, the present invention is a Cr-based stainless steel having excellent corrosion resistance with a pitting corrosion potential of more than 150 mV (vs Ag / AgCl, saturated KCl), high wear resistance, and machinability even in the state of use. Providing steel wire or steel wire, enabling stainless steel wire (steel wire) with reduced manufacturing costs along with these characteristics, and as a result, increasing the durability of various parts themselves and reducing the total cost To the goal.

  As a result of various studies to solve the above-mentioned problems, the present inventors have regulated the amount of C based on Cr-based stainless steel, added an appropriate amount of an alloy element such as Mo, N, and the like of V, Ti, Nb. Clarification of the relationship between the total amount of three types and C, and the PI value, and a metal structure in which a certain amount of hard carbonitride (carbide + nitride) is finely dispersed in the ferrite structure matrix of the material Thus, it has been found that a Cr-based stainless steel wire or steel wire having excellent wear resistance and corrosion resistance can be stably obtained with cold working (without quenching treatment). It was confirmed that it is suitable as a lead material by forming a strip by a predetermined rolling process. This invention is made | formed based on the said knowledge, The place made into the summary is as follows.

That is, the gist of the present invention is as follows.
(1) By mass%, C: 0.10 to 0.30%, Si: 0.05 to 2.0%, Mn: 0.1 to 1.5%, Cr: 12 to 17.5%, Mo : 0.05 to 3.0%, N: 0.005 to 0.15%, Nb: 0.05 to 1.0%, Ti: 0.05 to 1.0%, V: It contains one or more of 0.05 to 1.0%, the remainder is composed of Fe and inevitable impurities, the PI value shown by the formula (A) is 14.0 or more, and the CI shown by the formula (B) The value of 3 to 15 is satisfied, and the total amount of carbonitride (carbide + nitride) is contained in the matrix of ferrite structure. Features, wear resistance, corrosion resistance and cold workability Cr-based stainless steel wire rod excellent in
PI value = Cr + 3Mo-17C-7N --------------- (A)
CI value = (V + Ti + Nb) / C −−−−−−−−−−−−−−− (B)
(2) Cr having excellent wear resistance, corrosion resistance and cold workability as described in 1 above, wherein all of V, Ti and Nb are included and the total is 0.3 to 1.2% Stainless steel wire.
(3) The Cr-based stainless steel wire excellent in wear resistance, corrosion resistance and cold workability as described in 1 or 2 above, further comprising, by mass%, B: 0.001 to 0.015% It is .
(4 ) Further, by mass%, Al: 0.01 to 0.2%, Ca: 0.001 to 0.02%, Mg: 0.001 to 0.02%, Zr: 0.0005 to 0. The Cr-based stainless steel wire material having excellent wear resistance, corrosion resistance, and cold workability according to any one of the above items 1 to 3 , characterized by containing one or more of 02%.
(5) the 1 to the wear resistance of and having a chemical composition and metal structure according to any one of 4, a stainless steel steel wire excellent in corrosion resistance and cold workability.
(6) Having the chemical composition and metal structure described in any one of 1 to 4 above, and further in mass%, Ni: 0.1 to 1.4%, Cu: 0.1 to 2.0%, Sn : A Cr-based stainless steel wire for a lead material of a weaving machine excellent in wear resistance, corrosion resistance and cold workability, characterized by containing at least one of 0.05 to 0.3%.
(7) A stainless steel wire for a lead material of a weaving machine having excellent wear resistance, corrosion resistance and cold workability, characterized by having the chemical composition and metal structure described in (6) above.
( 8 ) A lead material for a weaving machine having the chemical composition and metal structure described in any one of 1 to 4 and 6 , and having a surface hardness of 300 to 500 Hv.

  The Cr-based stainless steel of the present invention refers to stainless steel (ferritic and martensitic stainless steel) containing Cr as a main element that does not contain much Ni (≦ 2.0 mass%) and has a bcc crystal structure. .

  “Wire” refers to ROD that has been melted and hot-rolled, etc. “Steel wire” is a wire that has been further drawn or rolled to the specified dimensions and characteristics. Indicates.

  The Cr-based stainless steel wire or steel wire for wear resistance according to the present invention does not require quenching and tempering treatment as it is cold-worked on the product, and can provide wear resistance and corrosion resistance, thus dramatically improving the cost performance of the product. The effect which improves automatically.

  Below, the reason for limitation of Claim 1 of this invention is demonstrated first.

C can form carbides such as M ₂₃ C ₆ , M ₇ C ₃ , and M ₃ C (M represents Cr, Fe, Mo, V, Nb, Ti, etc.) and can improve wear resistance. Add at least 05%. However, when added in a large amount as shown in the Examples of Patent Document 7, the probability of Cr carbide generation is increased, and although it is preferable for wear resistance, the corrosion resistance is deteriorated and the cold workability is also decreased at the same time. Become. Therefore, in the present invention, C is fixed by V, Ti, and Nb, but the upper limit is set to 0.30%. More preferably, it is 0.07 to 0.15%.

  Si is necessary for deoxidation, and is added in an amount of 0.05% or more in order to promote precipitation of carbonitrides and ensure wear resistance. However, if it exceeds 2.0%, cold workability is deteriorated. Therefore, the upper limit is limited to 2.0%. A preferred range is from 0.1% to 1.0%.

  Mn is an element necessary for deoxidation, and is added in an amount of 0.1% or more. However, if added over 1.5%, it becomes difficult to ensure cold workability by annealing. Therefore, the upper limit is limited to 1.5%. A preferable range is 0.2 to 0.8%.

  Cr is added in an amount of 12% or more in order to ensure corrosion resistance and to form carbonitrides to ensure wear resistance. However, if added over 17.5%, the cold workability deteriorates due to coarse carbonitride. Therefore, the upper limit is limited to 17.5%. A preferred range is 13-17%.

  Mo is added at 0.05% or more in order to ensure corrosion resistance and at the same time add together with N to finely disperse carbonitride to ensure wear resistance. However, if it exceeds 3.0%, cold workability deteriorates. Therefore, the upper limit is limited to 3%. A preferable range is 0.5 to 2.5%.

N forms nitrides such as M ₂ N and MN (M represents Cr, Fe, Mo, W, V, Nb, Ta, Hf, etc.) and is added together with Mo to add carbonitride. Add 0.005% or more in order to finely disperse and improve wear resistance. However, if it exceeds 0.15%, the quality is significantly degraded by blow holes. Therefore, the upper limit is limited to 0.15%. A preferable range is 0.02 to 0.12%. In addition, although the N amount absorbed from the surface layer of the steel material by nitriding heat treatment or the like is included, the N amount in the present invention is an average value from the surface layer to the center of the wire material.

  V, Ti, and Nb are effective in forming carbonitride, and the hardness of the carbonitride is extremely high as Hv: 2200 to 3200.

Also, in ordinary Cr-based stainless steel, a large amount of carbides such as (Cr, Fe) ₂₃ C ₆ and Cr and Fe are formed, but these carbides are easily coarsened and used for a long time at high temperatures. It is known to decrease in strength and also causes deterioration of corrosion resistance. The addition of V, Ti, or Nb is effective in suppressing the formation of Cr carbonitride that causes deterioration of corrosion resistance, and obtaining a finely dispersed carbonitride instead. Therefore, 0.05% or more of one or more of V, Nb, and Ti is added. However, if it exceeds 1.0%, cold workability deteriorates. Therefore, the upper limit is limited to 1.0%. A preferable range is 0.1 to 0.7%.

  The PI value shown in the formula (A) affects the corrosion resistance of the product. In particular, when the PI value is less than 14.0, it occurs in the atmospheric environment and causes problems. Therefore, the PI value is limited to 14.0 or more. Preferably it is 15.0 or more, more preferably 16.0 or more.

  Further, the formula (B) indicating the relationship between the third element and C by Nb, Ti, and V affects the suppression of the formation of Cr carbonitride that deteriorates the corrosion resistance. Addition of N, Ti, V more than 3 times the amount of C is effective in suppressing deterioration of corrosion resistance. Therefore, the CI value (Carbide Index) is limited to 3 or more. However, if it exceeds 15, the carbonitride becomes coarse and the cold workability deteriorates, so the upper limit is limited to 15. More preferably, it is 5-10.

  The metal structure is a structure in which the carbonitride (carbide and nitride) is dispersed in a ferrite structure matrix in order to ensure wear resistance and cold workability. The structure is determined by observing the thin film sample with a transmission electron microscope and determining whether it is decomposed into a ferrite structure and carbonitride (carbide + nitride) having a low dislocation density. If the hardness is 270 Hv or less, the structure is determined to be a ferrite and carbonitride structure defined in the present invention. An example of the distribution state of the carbonitride in the wire is shown in the micrograph (100 times) in FIG. 1, and the steel wire and the lead material tend to change, for example, slightly refined or uniformly dispersed.

  Preferably, the fine particle diameter is 10 μm or less (more preferably 5 μm or less) in the wire state, and 5 μm or less (more preferably 2 μm or less, and further 0.5 μm or less) in the steel wire and the lead material.

  The total amount (mass%) of carbonitride is limited to 1% or more in order to ensure wear resistance and cold workability, and the matrix is controlled to a ferrite structure. However, when it exceeds 8%, cold workability and corrosion resistance deteriorate. Therefore, the upper limit is limited to 8%. A preferred range is 2-7%. Carbonitride refers to one or more precipitates of carbide and nitride. Moreover, although the measurement of the total amount (mass%) of carbonitride is described in detail in the Examples, it is carried out by electrolytic separation in a non-aqueous solution.

  The method for controlling the total amount of carbonitride to 1% or more is adjusted by the lower limit of C amount (%) and N amount (%) and the annealing method, and the method for controlling it to 8% or less is C amount (%). Adjust the upper limit of N amount (%). In order to control the total amount of the carbonitride of the present invention, annealing is performed at an annealing temperature of 600 to 950 ° C. and an annealing time of about 3 to 300 minutes. In some cases, annealing is performed slowly (cooling speed; about 5 to 60). C./h). Annealing below 600 ° C. results in insufficient carbonitride precipitation (total amount of carbonitride), and annealing above 950 ° C. is uneconomical.

  Next, the reason for limiting the chemical composition (mass%) according to claim 2 of the present invention will be described.

  Since the amount that can be added as a single element of the third element of V, Ti and Nb is naturally limited in terms of material composition or cost, etc., in the present invention, each element is added together (combined addition) as necessary. By making the total 0.3 to 1.2%, the above effect is obtained by an easier method.

  Next, the reason for limiting the chemical composition (mass%) according to claim 3 of the present invention will be described.

  B is added in an amount of 0.001% as necessary in order to disperse carbonitride uniformly and finely to improve wear resistance. However, if added over 0.015%, the cold workability deteriorates due to the formation of coarse boride. Therefore, the upper limit is limited to 0.015%. A preferred range is 0.002 to 0.008%.

  Next, the reason for limiting the chemical composition (mass%) according to claim 4 of the present invention will be described.

  Ni is added in an amount of 0.1% or more as necessary in order to ensure corrosion resistance. However, if added excessively, it becomes difficult to ensure cold workability by annealing. Therefore, it is limited to 2.0% or less. A preferable range is 0.1 to 1.4%.

  In order to ensure corrosion resistance, Cu and Sn are added as necessary: Cu: 0.1% or more, Sn: 0.05% or more. However, if added excessively, it becomes difficult to ensure cold workability by annealing. Therefore, it is limited to Cu: 2.0% or less and Sn; 0.3% or less, respectively. Preferred ranges are Cu: 0.1 to 0.5%, Sn; 0.05 to 0.15%.

  Next, the reason for limiting the chemical composition (mass%) according to claim 5 of the present invention will be described.

  Al, Ca, Mg, and Zr are Al; 0.01% to 0.2%, Ca; 0.001% to 0.02%, respectively, for the purpose of strengthening deoxidation as necessary. Mg: 0.001 to 0.02%, Zr: 0.0005 to 0.02% is added. Here, when excessively added, the coarse deoxidation product deteriorates the cold workability and the corrosion resistance, so the upper limit is set respectively.

  The invention of claim 6 is a wear-resistant stainless steel wire excellent in corrosion resistance and cold workability, characterized by having the chemical composition and metal structure described in any one of the above.

  Further, according to the invention of claim 7, any one of the above steel wires is formed into a strip having a predetermined cross-sectional dimension by cold rolling, and the processing is used as a lead material for a weaving machine having a surface hardness of 300 to 500 Hv. . The dimensions are, for example, a thickness of about 0.1 to 1.5 mm and a width of about 1.5 to 3.0 mm. More preferably, after hardening once by wire drawing, rolling is continued to widen the width. Rolling process becomes easy.

  Examples of the present invention will be described below.

  Table 1 shows the chemical composition of the steels of the examples.

  Steels of these chemical compositions are melted in a 100 kg vacuum melting furnace, cast into a slab of φ180 mm, the slab is hot-rolled to φ5.5 mm, and hot rolling is finished at 1000 ° C. Cooled to room temperature. The wire was annealed and annealed at 850 ° C. for 2 hours in a batch furnace to obtain a ferrite and carbonitride structure. Thereafter, pickling was performed, and cold wire drawing was performed to various diameters in order to investigate cold workability. For materials drawn to φ3 mm, the wear resistance, corrosion resistance, and total amount of carbonitride were investigated. The results are shown in Table 2.

  The cold workability was obtained by drawing a φ5.5 mm wire to φ2 mm. And if wire-drawing was possible to a reduction in area of more than 80%, the cold workability was evaluated as ◯, and the case where wire-drawing was impossible due to disconnection, vertical cracking, etc. was evaluated as x. The cold workability of the inventive examples was all good.

Abrasion resistance was evaluated by reducing the wear by polishing the cross section of the wire drawing material with # 1000 and pressing the polished surface against a rotating polishing disk to generate friction. The abrasive disc was prepared by uniformly mixing 0.1 μm TiO ₂ particles and a polyester resin at a ratio of 1: 3 and making them hard. As for the friction conditions, the contact pressure was 15 g / cm ² , the friction speed was 2 m / s, the friction distance was 50 km, and the mass difference before and after the test was measured. The wear loss of the inventive examples was 50 μg / cm ² · km or less.

  For corrosion resistance, the steel wire was cut to a length of 100 mm, and the entire surface was polished by # 500, and a corrosion test for 100 hours was performed by a salt spray test of JIS Z2731. And after the test, the bruising situation was evaluated in five stages. A was evaluated as no rust, B as spot rust, C as slight flow rust, D as severe flow rust, and E as overall rust. The corrosion resistance of the examples of the present invention was A or B.

  The total amount (mass%) of carbonitride was obtained by electrolysis (100 mV constant voltage) of 3 g of wire drawing material with a surface layer of # 500 polished in a non-aqueous solution (3% maleic acid + 1% tetramethylammonium croid + remaining methanol). The matrix was dissolved and filtered through a 0.2 μm hole diameter filter to extract carbonitride. And the total mass% of the carbonitride was computed by mass measurement after 1 hour progress. The identification of X-ray diffraction confirmed that the precipitates were substantially carbides and nitrides. The total amount of carbonitrides of the inventive examples was in the range of 1 to 8%.

  On the other hand, Comparative Example No. Nos. 26 to 48 are examples of the present invention. 1-No. Compared to 25, any of wear resistance, corrosion resistance, or cold workability is inferior.

  Next, in order to investigate the influence of the structure on the properties, the φ5.5 mm wire having the chemical composition of the steel B of the present invention described above was annealed and gradually cooled in a batch furnace at 700 to 900 ° C. for 60 minutes to produce ferrite. And carbonitride structure. Moreover, the said wire was hardened at 1050 degreeC as a comparative material, Then, it annealed (slow cooling) at 200 to 500 degreeC, and made the structure | tissue state martensite or tempered martensite. These wires were examined for cold drawing workability, wear resistance, corrosion resistance and total amount of carbonitride by the same method as above, and the results are shown in Table 3.

  The microstructure is a ferrite and carbonitride structure when a thin film sample is prepared from a wire before cold drawing and the structure is observed with a transmission electron microscope, and a ferrite structure and carbonitride with low dislocation density are observed. The case of only the lath martensite structure was defined as the martensite structure, and the state in which fine carbonitrides precipitated between the lath martensite and the lath was defined as the tempered martensite structure. The structure of the steel of the present invention was a structure of ferrite and carbonitride, and showed good cold workability.

  On the other hand, Comparative Example No. Nos. 51 and 52 are tempered martensite and martensite structures in the matrix, and are inferior in cold workability.

  Next, the steel wire drawn to φ1.6 mm of the steel B (No. 2) and the steel Z (No. 26, SUS430) was annealed at a temperature of 780 ° C., and cold drawn with a processing rate of 50%. The lead material made of a hard strip material having a width of 2.2 mm and a thickness of 0.28 mm was subsequently processed by a multi-stage rolling mill. The analysis of the carbonitride of the band material and the wear resistance and corrosion resistance were also performed in the same manner as described above, and the surface hardness of the band material was measured by a JIS method with a load of 1 kg. The results are shown in Table 4.

  Comparative Example No. As compared with the band material of SUS430 of 54, the present invention example No. It can be seen that the wear resistance of the band 53 is significantly superior.

  As can be seen from the above examples, the superiority of the steel of the present invention is clear.

  As is clear from each of the above examples, the present invention provides an inexpensive Cr-based stainless steel wire or steel wire that does not require quenching / tempering treatment and can impart wear resistance and corrosion resistance while still being cold worked. It is extremely useful industrially as general-purpose wear-resistant materials such as shafts and miniature ropes and lead materials for looms.

The microscope picture which shows an example of the distribution state of carbonitride.

Claims (8)

In mass%, C: 0.10 to 0.30%, Si: 0.05 to 2.0%, Mn: 0.1 to 1.5%, Cr: 12 to 17.5%, Mo: 0.00. 0.5 to 3.0%, N: 0.005 to 0.15%, Nb: 0.05 to 1.0%, Ti: 0.05 to 1.0%, V: 0.05 -1% or more of -1.0%, the balance is composed of Fe and inevitable impurities, the PI value shown by the formula (A) is 14.0 or more, the CI value shown by the formula (B) is 3 It is excellent in wear resistance, corrosion resistance and cold workability characterized by containing 1 to 8% of carbonitride (carbide + nitride) in the total amount in the matrix of ferrite structure while satisfying the condition of ~ 15 Cr-based stainless steel wire.
PI value = Cr + 3Mo-17C-7N -------------- (A)
CI value = (V + Ti + Nb) / C −−−−−−−−−−−−−− (B) The Cr-based stainless steel excellent in wear resistance, corrosion resistance and cold workability according to claim 1, characterized in that all of V, Ti and Nb are included and the total is 0.3 to 1.2%. Steel wire rod. The Cr-based stainless steel wire excellent in wear resistance, corrosion resistance and cold workability according to claim 1 or 2, further comprising B: 0.001 to 0.015% by mass. Furthermore, by mass%, Al: 0.01 to 0.2%, Ca: 0.001 to 0.02%, Mg: 0.001 to 0.02%, Zr: 0.0005 to 0.02% Among them, the Cr-based stainless steel wire material having excellent wear resistance, corrosion resistance, and cold workability according to any one of claims 1 to 3, comprising at least one kind. A stainless steel wire excellent in wear resistance, corrosion resistance and cold workability , characterized by having the chemical composition and metal structure according to any one of claims 1 to 4 . It has the chemical composition and metal structure according to any one of claims 1 to 4, and is further in mass%, Ni: 0.1 to 1.4%, Cu: 0.1 to 2.0%, Sn: 0 A Cr-based stainless steel wire for a lead material of a weaving machine excellent in wear resistance, corrosion resistance and cold workability, characterized by containing at least one of 0.05 to 0.3%. A stainless steel wire for a lead material of a weaving machine with excellent wear resistance, corrosion resistance and cold workability, characterized by having the chemical composition and metal structure according to claim 6. Has a chemical composition and metal structure according to any one of claims 1 to 4, 6, lead material for the loom reed, characterized in that the surface hardness 300～500Hv.