JP2005256114A - Method for producing high wear resistant and high corrosion resistant stainless steel material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily produce a material having wear resistance and corrosion resistance required for parts of weaving machine etc. <P>SOLUTION: A slab of stainless steel material, composed of 0.03-0.30% C, ≤3.0% Si, ≤3.0% Mn, 5.0-20.0% Ni, >15.0%-30.0% Cr, ≤0.030% N and the balance Fe with inevitable impurities, is prepared. After applying hot-rolling to the slab, a solid solution heat-treatment is performed and successively, cold-rolling is performed and further, the carbide and the carbonitride are precipitated by applying continuous annealing in the temperature range of 700-950°C, and thereafter, a process for finish cold-rolling is provided as the producing method for the stainless steel material excellent in the wear resistance and the corrosion resistance. Further, the cold-rolling is performed and successively, the precipitation of the carbide by applying the continuous annealing in the temperature range of 700-950°C, is repeated at one or more times and thereafter, the finish cold-rolling is applied. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stainless steel material that requires wear resistance and corrosion resistance. More specifically, the present invention relates to a high-strength stainless steel material that is required for wear resistance and corrosion resistance and that is suitable for use in equipment such as wings and healds.

  The basic operation of the loom will be described with reference to the schematic diagram of the loom of FIG. The wings and healds in FIG. 6 are used to guide the warp and the weft, respectively. The weft is supported by the heald and moves up and down alternately and passes between the wings arranged at equal intervals. On the other hand, the warp is driven by the power of, for example, an air jet or a water jet each time the wefts alternately move up and down, and passes between the wefts. Next, after the warp passes, the wings move back and forth, and the weft and the warp are woven into a woven fabric.

  Since the yarn passes at high speed during weaving, the weft, the cocoon and the heald that are in contact with the warp, as described above, wear out when used for a certain period of time. When the wings and healds wear, the worn parts cause thread breakage and fluffing, and therefore must be replaced each time. Therefore, it can be said that the wear resistance of the wing and heald yarn is one of the most important qualities that determine the life of the wing and heald.

  The ambient atmosphere at the time of weaving is always a moist environment in a water jet loom. Even in the case of an air jet loom, it is often exposed to a corrosive environment by a dye or the like. For this reason, when rust is generated on the wings and healds, the rusted portion causes thread breakage and fluffing as in the case of wear. Therefore, corrosion resistance is also required for wings and healds.

Therefore, high strength stainless steel such as austenitic stainless steel represented by SUS301 hard material and martensitic stainless steel containing carbide represented by SUS420J2 is used for the weaving parts.
JP 2003-105504 A JP 2003-147493 A

  By the way, although the SUS301 hard material has corrosion resistance, the wear resistance is insufficient for the weaving parts. For this reason, measures have been taken to harden the surface layer portion that is subject to wear by a ceramic coating method or the like. However, such a surface treatment method has a problem that the manufacturing cost becomes high.

  On the other hand, SUS420J2 is excellent in wear resistance, but is inferior in corrosion resistance due to a small amount of Cr effective for corrosion resistance. Moreover, in order to ensure intensity | strength, since hardening and tempering were performed, there existed a problem that manufacturing cost became high.

  In order to improve the wear resistance while maintaining the corrosion resistance, a method for improving the wear resistance of the austenitic stainless steel is effective. Japanese Patent Application Laid-Open No. 2003-105504 describes a technique for improving wear resistance by precipitating a large amount of Cr carbonitride in the parent phase by performing heat treatment for a long time after rolling in austenitic stainless steel. Has been.

  However, this method has a problem that a large amount of coarse Cr carbides and carbonitrides are precipitated, and ear cracks occur during cold rolling starting from these, and the risk of breakage increases during rolling. Furthermore, since the amount of Cr in the matrix that is effective for corrosion resistance is taken by carbides and carbonitrides, there is also a problem that the corrosion resistance deteriorates.

  Accordingly, it is an object of the present invention to more easily produce and provide a material having wear resistance and corrosion resistance necessary for a weaving part or the like.

In order to solve the above-mentioned problems, the first aspect of the present invention includes the following steps (hereinafter,% indicates mass%), and the production of a stainless steel material excellent in wear resistance and corrosion resistance: Is the method.
(A) As component composition, C: 0.03 to 0.30%, Si: 3.0 or less, Mn: 3.0% or less, Ni: 5.0 to 20.0%, Cr: more than 15.0 ~ 30.0% or less, N: 0.030% or less, and a slab of stainless steel material comprising the balance Fe and unavoidable impurities,
(B) Hot rolling is performed on the slab, followed by a solution heat treatment, followed by cold rolling,
(C) Subsequently, continuous annealing is performed in a temperature range of 700 to 950 ° C. to precipitate carbide and carbonitride,
(D) Thereafter, finish cold rolling is performed.

  In the second aspect of the present invention, the cold rolling is performed, followed by continuous annealing in a temperature range of 700 to 950 ° C. to precipitate carbides one or more times, and then finishing. A method for producing a stainless steel material having excellent wear resistance and corrosion resistance, characterized by cold rolling.

  A third aspect of the present invention is a method for producing a stainless steel material having excellent wear resistance and corrosion resistance, wherein the rolling rate of the cold rolling is 30% or more.

  A fourth aspect of the present invention is a method for producing a stainless steel material excellent in wear resistance and corrosion resistance, characterized by performing heat treatment in a temperature range of 200 to 700 ° C. after the finish cold rolling.

  A fifth aspect of the present invention is a method for producing a stainless steel material excellent in wear resistance and corrosion resistance, wherein the stainless steel material further contains 4.0% or less of Mo as a component composition. .

  According to a sixth aspect of the present invention, the stainless steel material further includes, as a component composition, V: 1.0% or less, Ti: 1.0% or less, Nb: 1.0% or less, Zr: 1.0% or less. It is the manufacturing method of the stainless steel material excellent in abrasion resistance and corrosion resistance characterized by containing at least 1 or more types chosen from these.

  In the seventh aspect of the present invention, the area ratio of the carbide and carbonitride precipitated in the metal structure of the stainless steel material is 10% or more, and the average diameter of the precipitated carbide and carbonitride is 1 μm or less. It is a method for producing a stainless steel material having excellent wear resistance and corrosion resistance.

  According to the present invention, stainless steel having good wear resistance, corrosion resistance and manufacturability can be obtained by precipitating and dispersing carbide and carbonitride based on austenite. By using the product of the present invention, it has the effect of extending the life when used in fields where wear resistance and corrosion resistance are required, for example, machine tools such as wings and healds, press plates, switch connectors, and blades. The presence of the steel of the present invention is extremely effective.

  It is well known that to improve the wear resistance without surface treatment, it is effective to harden the matrix and uniformly disperse the hard second phase particles in the matrix. In the present invention, the surface layer is not hardened by surface treatment, but hard carbides and carbonitrides are precipitated and dispersed in the parent phase to improve wear resistance. Furthermore, it is characterized by performing corrosion resistance with austenitic stainless steel.

  Hard carbides and carbonitrides precipitated in the matrix are not coarse and are finely and uniformly dispersed. Accordingly, ductility that can withstand cold rolling can be maintained, wear resistance can be further improved, and deterioration of corrosion resistance can be prevented.

  Precipitation of carbides and carbonitrides is recognized in some steel types such as ferritic stainless steel and martensitic stainless steel. However, in ferritic stainless steel, the hardening of the parent phase is limited, and wear resistance has only the effect of carbide, so there is a natural limit to improving wear resistance.

  On the other hand, martensitic stainless steel can ensure the hardness of the parent phase, but there is a problem in corrosion resistance because the Cr amount effective for corrosion resistance cannot be increased in order to obtain a martensitic structure. Further, since the quenching and tempering processes are always required in the manufacturing process, the manufacturing cost may be increased.

  Therefore, we will investigate high wear resistance and high corrosion resistance using austenitic stainless steel, and disperse in the matrix the carbides and carbonitrides mainly composed of Cr that can be easily deposited on stainless steel. Started.

  However, if the precipitation amount of carbide and carbonitride is excessively large, Cr in the parent phase effective for corrosion resistance is taken up by the precipitate, and the corrosion resistance is deteriorated. Therefore, the amount of precipitation of carbides and carbonitrides, that is, the area ratio, is defined from the aspects of wear resistance and corrosion resistance.

  Moreover, when the carbide | carbonized_material and carbonitride to precipitate are coarse, it will become a starting point of a crack at the time of cold rolling, and will cause a rolling fracture. Accordingly, carbides and carbonitrides place an upper limit on their average diameter.

  The amount and size of the precipitated carbide and carbonitride can be controlled by the cold rolling rate and the subsequent heat treatment temperature conditions. Carbide rolling and carbonitride can be uniformly and finely dispersed by performing cold rolling at a processing rate of 30% or more according to the present invention and then performing heat treatment (continuous annealing) by continuous annealing.

  In the present invention, a slab of a stainless steel material having the following component composition and the balance of Fe and inevitable impurities is prepared, subjected to hot rolling, then subjected to solution heat treatment, then cold rolled, and subsequently 700 It is characterized in that continuous annealing is performed in a temperature range of ˜950 ° C. to precipitate carbides and carbonitrides, and then finish cold rolling is performed.

First, the reason for limiting the component composition in the invention will be described below.
C: 0.03 to 0.30%, C is not only a strong austenite-forming element, but also an element constituting carbide and carbonitride, so that it is preferable to increase the wear resistance. The above is necessary. However, if it contains more than 0.30 wt%, coarse undissolved carbides are generated and the risk of cold rolling breakage is increased, and corrosion resistance is also deteriorated, so 0.03 to 0.30 wt%, preferably 0 0.05 to 0.25 wt%, more preferably 0.10 to 0.25 wt%.

  Si: 3.0 or less, Si is an element necessary for deoxidation and effective for increasing the strength. However, if it exceeds 3.0 wt%, the risk of cold rolling breakage increases. 0 wt% or less.

  Mn: 3.0% or less, Mn is an element necessary for deoxidation as well as Si, and is an austenite forming element. Therefore, it is necessary for obtaining an austenite structure. In order to cause abnormal oxidation during annealing pickling and lead to a decrease in yield, the content is set to 3.0 wt% or less.

  Ni: 5.0-20.0%, Ni is a strong austenite forming element, and 5 wt% or more is necessary. However, it is an expensive element, and the upper limit is 20 wt%, and is 5.0 to 20.0 wt%, preferably 5.0 to 15.0 wt%.

  Cr: more than 15.0 to 30.0% or less, Cr is an element that forms carbides and is also effective for improving corrosion resistance. Therefore, it is necessary to contain more than 15.0 wt%. However, if it contains more than 30.0 wt%, the σ phase precipitates, and conversely, corrosion resistance is impaired and manufacturability is also deteriorated, so the upper limit is made 30.0 wt%, more than 15.0 to 30.0 wt%, preferably Over 15.0 to 25.0 wt%.

  N: 0.030% or less, N containing more than 0.30 wt%, the risk of cold rolling breakage is increased, so 0.30 wt% or less. However, since it is effective for increasing strength and improving corrosion resistance, when these effects are required, it is preferably 0.02 to 0.25 wt%, more preferably 0.05 to 0.20 wt%.

  P is an element contained in scrap and is an element that is difficult to remove by refining. However, if it exceeds 0.045%, corrosion resistance is deteriorated, so 0.045 wt% or less is desirable.

  S is an element contained in scrap, and it takes cost to remove it by refining. However, if it exceeds 0.01 wt%, corrosion resistance is deteriorated and hot workability is also deteriorated. % Or less is desirable.

  In the present invention, after a hot rolling process is performed on a slab to obtain a band having a predetermined thickness, solid carbides and carbonitrides generated during hot rolling are dissolved in the matrix and during hot rolling. A solution heat treatment is performed to remove the strain generated in the film. The temperature range is preferably 1000 to 1,150 ° C., and the time is preferably 30 seconds to 10 minutes. It is appropriate to use a continuous annealing furnace in the air atmosphere.

  In the present invention, by increasing the rolling rate in cold rolling, the precipitation sites of carbide and carbonitride increase in the subsequent continuous annealing, and fine carbide and carbonitride can be uniformly dispersed. It becomes possible.

  For continuous annealing, if the continuous annealing temperature is too low, the driving force necessary for precipitation is insufficient, and not only does not reach a sufficient amount of precipitation, but also the ductility becomes poor after heat treatment, and there is a risk of fracture in the subsequent rolling process. Will increase. Therefore, it is necessary to implement at 700 degreeC or more industrially. On the other hand, when the heat treatment temperature is set to a high temperature, the amount of precipitation decreases. Moreover, since carbide and carbonitride re-dissolved in the parent phase and the wear resistance deteriorates, the upper limit was set to 950 ° C. In addition, Preferably it is set as 800-900 degreeC.

  The annealing time is desirably 30 seconds to 10 minutes. If the annealing time is long, the carbides and carbonitrides become coarse, which increases the risk of breakage in the rolling process and also deteriorates the corrosion resistance. In addition, productivity may be reduced. If the annealing time is short, the driving force necessary for precipitation is insufficient, and a sufficient amount of precipitation is not achieved. As a result, the wear resistance is degraded.

  The annealing furnace is desirably a bright annealing (BA) furnace that performs annealing in a hydrogen-nitrogen atmosphere or a continuous annealing furnace that performs annealing in an air atmosphere.

  In the present invention, the above-described cold rolling is performed, followed by continuous annealing in a temperature range of 700 to 950 ° C. to precipitate carbides one or more times, and then finish rolling.

  That is, the above carbides and carbonitrides are precipitates mainly composed of Cr. In order to form carbides and carbonitrides as described above, carbides are precipitated by repeating the continuous annealing once or twice or more.

  For example, if batch annealing is performed for a long time, the amount of precipitated carbides and carbonitrides increases and wear resistance is improved, but the grain size becomes coarse and the ductility becomes poor, and the possibility of rolling breakage increases. . In addition, when the amount of precipitated carbide and carbonitride is large, the amount of Cr in the matrix is reduced and the corrosion resistance is also deteriorated. For this reason, the carbide precipitation heat treatment avoids long-time heat treatment by batch, and selects short-time heat treatment by cold rolling and continuous annealing.

  When cold rolling and continuous annealing are repeated, a large amount of carbide and carbonitride precipitates, so that wear resistance is improved. However, increasing the number of repetitions leads to a decrease in the toughness of the material and increases the risk of rolling breakage. Further, since the amount of Cr in the matrix is reduced, the corrosion resistance is also deteriorated. Therefore, the number of repetitions is preferably 1 to 3 times.

  The present invention is characterized in that a rolling rate of the cold rolling is 30% or more. That is, the reason for setting it as 30% or more is that the precipitation site | part of the carbide | carbonized_material and carbonitride in a continuous annealing process increases, and it becomes possible to disperse | distribute fine carbide | carbonized_material and carbonitride uniformly. If it is less than 30%, there are few carbide and carbonitride precipitation sites in the continuous annealing step, and the carbides and carbonitrides become coarse and the amount of precipitation also decreases.

  In the present invention, after the finish cold rolling, a stress relief heat treatment is performed in a temperature range of 200 to 700 ° C. By performing this stress-relieving heat treatment, it is possible to improve wear resistance and toughness, and to facilitate subsequent processing into loom parts and the like. Also, the shape of the plate may be corrected.

  In the present invention, Mo may be added as a component composition. Mo is an element effective for improving the corrosion resistance, but is an extremely expensive element, so it may be contained at 4.0 wt% or less.

  Moreover, in this invention, the slab of the stainless steel material which added 1.0 wt% or less of any 1 or more types of V, Ti, Nb, and Zr can be used. That is, V, Ti, Nb, and Zr combine with C or N to form stable carbides and carbonitrides and refine the austenite structure.

  Therefore, when the precipitation heat treatment of the carbide and carbonitride of the present invention is performed, it becomes a Cr carbide and carbonitride production site and acts advantageously on the formation of Cr carbide and carbonitride. If it is in the range of 0 wt% or less, it may be added. However, since any element is expensive or added in excess of 1.0 wt%, coarse carbides and carbonitrides are formed to impair manufacturability. Therefore, 1.0 wt% or less, preferably 0.5 wt% If it is in the range of% or less, it may be added.

  The structure of the stainless steel material obtained by the above method is composed of austenite, work-induced martensite formed by cold rolling, and carbides and carbonitrides precipitated during continuous annealing. In the present invention, the area ratio occupied by the precipitated carbide and carbonitride is 10% or more. The wear resistance can be greatly improved by precipitation of carbides and carbonitrides, but the effect is small at less than 10%, so the lower limit is 10%.

  Furthermore, in the present invention, the average diameter of the precipitated carbide and carbonitride is 1 μm or less. In order to have good wear resistance, it is desirable that the precipitated carbide and carbonitride are finely dispersed. On the other hand, if the average diameter exceeds 1 μm, the precipitated carbides and carbonitrides become the starting point of cold rolling breakage and impair manufacturability, so the average diameter is 1 μm or less.

  Here, the area ratio and the diameter of the precipitated carbide and carbonitride can be obtained using a photograph taken with an electron microscope.

  Evaluation was performed using a stainless steel material having the composition shown in Table 1 as FIG. Examples a to d shown in Table 2 as FIG. 2 and Table 3 as FIG. 3 are examples of the present invention. For a hot-rolled sheet having a thickness of 3.5 mm, after performing a solution heat treatment at 1100 ° C. for 1 minute, repeated cold rolling and carbide heat treatment, and after finishing cold rolling, each evaluation was performed. It was.

  E to h in Table 2 and Table 3 are comparative examples. e was manufactured using a normal stainless steel hard material manufacturing process in which a solution thickness heat treatment and cold rolling were repeated to obtain a predetermined plate thickness for a hot rolled plate having a plate thickness of 3.5 mm. The comparative example of fh was manufactured using the process of giving a hot carbide precipitation heat processing for 12 to 36 hours to a hot rolled sheet or a cold rolled sheet, and performing cold rolling after that.

  Table 3 summarizes the evaluation results. First, the metal structure will be described. The structure of the obtained plate material is composed of austenite, work-induced martensite formed by cold rolling, and carbonized and carbonitrides precipitated by heat treatment. A representative organization is shown in the photograph as FIG. The white spots in the photograph indicate carbides and carbonitrides. The structure of the plate material was observed using an electron microscope. The pretreatment was performed by cutting the manufactured plate material at a right angle to the rolling direction and polishing the surface, and then etching using a mixed solution of hydrochloric acid and picric acid alcohol.

  Next, the area ratio of carbide will be described. The area ratio of carbide is obtained by a point calculation method using a 3000 times photograph taken with an electron microscope. Specifically, a grid having vertical and horizontal intervals of 5 mm is provided on the photographer's field of view, for example, 10 in the vertical direction, 10 in the horizontal direction, touching the grid points of a total of 100 grids, or carbonized on the grid points. Ask for the number of relics. This operation is repeated 10 times, and the average value is defined as the area ratio.

That is, the area ratio is expressed by the following formula.
n ÷ (p × f) × 100 = Carbide area ratio (%), and n, p, and f indicate the following.
p: total number of lattice points in the field of view f: number of fields of view n: number of lattice point centers occupied by carbides in f fields of view

  For the size of the carbide, use a 3000 × photograph taken with an electron microscope, select the particles in the photographic field, determine the equivalent circle diameter, perform this work for 10 fields, determine the average value, and determine the carbide and carbonitride. The average value of the object particle diameters was used. The hardness was Vickers hardness obtained according to JISG0555.

  Abrasion resistance is determined by allowing the yarn to pass through the surface of the test material at a constant tension (35 g) for a certain period of time (5 hours) and forming abrasion at an accelerated rate. (Manufacturer; Tokyo Seimitsu Co., Ltd., model number: 1400A-3DF). The results are shown in Table 3. FIG. 5 shows the relationship between the maximum depth of wear scar (μm) and the carbonized area ratio (%). From this, it can be seen that the higher the carbide area ratio, that is, the higher the carbide precipitation amount, the better the wear resistance. In particular, the effect is large when the area ratio of carbide is 10% or more. In the example of the present invention, the wear scar depth is 15 μm or less, and the wear resistance is superior to 23 μm of SUS301. Of course, it is a value comparable to 12 μm of SUS420J2.

  The corrosion resistance was evaluated by obtaining a pitting potential measurement (method according to JISG0577). Higher pitting potential means better corrosion resistance. All of the products of the present invention exhibit excellent corrosion resistance compared to SUS420J, and are comparable to SUS301. In addition, the inventive product had a higher pitting corrosion potential than those subjected to a long-time carbide precipitation heat treatment, and both wear resistance and corrosion resistance were improved as compared with the previous invention product.

  The risk of breakage during cold rolling was evaluated by the maximum ear crack length. The edge crack is a phenomenon in which the edge of the test piece is cracked after cold rolling. If this occurs, the risk of rolling breakage increases due to the ear crack. A material with inferior processability has larger ear cracks, and the larger the diameter of carbide and carbonitride, the inferior processability. The product of the present invention does not cause ear cracks in the cold rolling process, and is not far from being manufactured.

  For example, it can be used for equipment such as wings, healds, etc. that require wear resistance and corrosion resistance.

It is Table 1 shown as FIG. 1, and is a component composition table | surface. It is Table 2 shown as FIG. 2, and is a manufacturing process list. It is Table 3 shown as FIG. 3, and is a list of test results. It is a representative photograph of the stainless steel structure of the present invention. It is the figure which showed the relationship between the maximum depth of wear length, and a carbide | carbonized_material area rate. It is a schematic diagram of a loom.

Claims (7)

The manufacturing method of the stainless steel material excellent in abrasion resistance and corrosion resistance characterized by providing the following process (Hereinafter,% shows mass%.).
(A) As component composition, C: 0.03 to 0.30%, Si: 3.0 or less, Mn: 3.0% or less, Ni: 5.0 to 20.0%, Cr: more than 15.0 ~ 30.0% or less, N: 0.030% or less, and a slab of stainless steel material comprising the balance Fe and unavoidable impurities,
(B) Hot rolling is performed on the slab, followed by a solution heat treatment, followed by cold rolling,
(C) Subsequently, continuous annealing is performed in a temperature range of 700 to 950 ° C. to precipitate carbide and carbonitride,
(D) Thereafter, finish cold rolling is performed.   The above-mentioned cold rolling is performed, and subsequently, continuous annealing is performed in a temperature range of 700 to 950 ° C. to precipitate carbides one or more times, and then finish cold rolling is performed. The manufacturing method of the stainless steel material excellent in abrasion resistance and corrosion resistance of Claim 1.   The method for producing a stainless steel material having excellent wear resistance and corrosion resistance according to claim 1 or 2, wherein a rolling rate of the cold rolling is 30% or more.   The method for producing a stainless steel material having excellent wear resistance and corrosion resistance according to any one of claims 1 to 3, wherein heat treatment is performed in a temperature range of 200 to 700 ° C after the finish cold rolling.   The method for producing a stainless steel material having excellent wear resistance and corrosion resistance according to any one of claims 1 to 4, wherein the stainless steel material further contains 4.0% or less of Mo as a component composition. .   The stainless steel material has, as a component composition, at least one selected from V: 1.0% or less, Ti: 1.0% or less, Nb: 1.0% or less, Zr: 1.0% or less. The method for producing a stainless steel material having excellent wear resistance and corrosion resistance according to any one of claims 1 to 5.   2. The area ratio of the carbide and carbonitride precipitated in the metal structure of the stainless steel material is 10% or more, and the average diameter of the precipitated carbide and carbonitride is 1 μm or less. The manufacturing method of the stainless steel material excellent in abrasion resistance and corrosion resistance of -6.

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