WO2016043050A1 - Acier inoxydable martensitique pour disque de frein et procédé de fabrication dudit acier - Google Patents

Acier inoxydable martensitique pour disque de frein et procédé de fabrication dudit acier Download PDF

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WO2016043050A1
WO2016043050A1 PCT/JP2015/074912 JP2015074912W WO2016043050A1 WO 2016043050 A1 WO2016043050 A1 WO 2016043050A1 JP 2015074912 W JP2015074912 W JP 2015074912W WO 2016043050 A1 WO2016043050 A1 WO 2016043050A1
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less
hot
stainless steel
ferrite
steel
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PCT/JP2015/074912
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English (en)
Japanese (ja)
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慎一 寺岡
井上　宜治
祐司 小山
濱田　純一
利男 田上
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新日鐵住金ステンレス株式会社
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Priority claimed from JP2015062216A external-priority patent/JP6417252B2/ja
Application filed by 新日鐵住金ステンレス株式会社 filed Critical 新日鐵住金ステンレス株式会社
Priority to CN201580050329.1A priority Critical patent/CN107075630B/zh
Priority to US15/511,905 priority patent/US20170253945A1/en
Publication of WO2016043050A1 publication Critical patent/WO2016043050A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D65/00—Parts or details
    • F16D65/02—Braking members; Mounting thereof
    • F16D65/12—Discs; Drums for disc brakes

Definitions

  • the present invention relates to a stainless steel plate for a brake disc of a motorcycle and a manufacturing method thereof, and relates to a martensitic stainless steel plate for a motorcycle brake disc having excellent surface and end surface properties.
  • ⁇ Brake discs for motorcycles are required to have wear resistance, weather resistance, toughness and other characteristics. Abrasion resistance generally increases with increasing hardness. On the other hand, if the hardness is too high, a so-called brake squeak occurs between the brake and the pad. Therefore, the hardness of the brake is required to be 32 to 38 HRC (Rockwell hardness C scale). Because of these required characteristics, martensitic stainless steel plates are used for the brake discs of motorcycles.
  • Patent Document 1 discloses an invention relating to a steel composition that can stably obtain a desired hardness in a wider quenching temperature range than conventional steel that is SUS420J2 steel and that is used as-quenched. It was. This is because, like SUS410, SUS403, and SUS410S steel, the reduction of C and the reduction of the austenite single-phase temperature range due to the reduction of C, that is, the quenching heating temperature range is narrowed by the addition of Mn, an austenite stabilizing element. It is a thing.
  • Patent Document 2 discloses an invention related to a steel plate for motorcycle disc brakes that is used as-quenched with low Mn steel. This steel sheet is obtained by adding Mn and simultaneously adding Ni and Cu having the same effect as an austenite forming element.
  • Patent Document 3 discloses an invention relating to a method for improving heat resistance by adding Nb and Mo.
  • Patent Document 4 discloses an invention relating to a disk material having excellent heat resistance by performing a quenching process from a temperature exceeding 1000 ° C.
  • Patent Document 5 discloses a brake disk having a martensite structure in which the average particle size of prior austenite grains is 8 ⁇ m or more
  • Patent Document 6 discloses that the area ratio of the structure after quenching is 75. % Or more is martensite and Nb is 0.10% or more and 0.60% or less.
  • Such low-C martensitic stainless steel has low hot workability and cracks at the end of the width during hot rolling, so that so-called ear cracks are likely to occur, so the components are controlled within a limited range where cracks are unlikely to occur. This is disclosed in Patent Document 7.
  • Patent Document 8 relates to a method for manufacturing a ferritic stainless steel strip.
  • the optimum conditions for heating the seat bar are disclosed, particularly with respect to a production method capable of producing a ferritic stainless hot-rolled steel strip excellent in forming processability and material uniformity with high productivity.
  • FIG. 1A shows an appearance of an edge seam ridge in the actual product
  • FIG. 1B shows a micrograph of a cross section of the edge seam ridge in the actual product.
  • the width is widened, and a part of the end face of the slab becomes the surface of the rough bar. Since the end face of the slab does not contact the rolling roll at the initial stage of rough hot rolling, the roughness is large, and when it comes into contact with the rolling roll after that, it causes wrinkles.
  • Edge seams are recognized in many hot-rolled steel strips of steel materials.
  • 80 mm thick steel ingots of various types of stainless steel were hot-rolled to 20 mm, and a photograph of the end face observed was shown in FIG. 2, but it can be seen that the degree of roughness of the end face varies greatly depending on the steel type.
  • SUS410 steel it turns out that the rough skin of an end surface changes greatly with hot rolling heating temperature. The rough surface on the end surface of the slab during rough hot rolling is caused by the difference in deformation mode due to the difference in crystal orientation of each crystal grain of the slab, and thus becomes prominent when the crystal grain size is coarse.
  • ⁇ is ⁇ ferrite
  • ⁇ is austenite
  • ⁇ is ⁇ ferrite
  • ⁇ ferrite but when expressed as ferrite, it usually means ⁇ ferrite.
  • ⁇ ferrite is ferrite precipitated at the A4 transformation point or higher
  • ⁇ ferrite is ferrite precipitated at the A3 transformation point or lower.
  • the temperature range in which the austenite single phase is formed is narrow, and a two-phase structure of ⁇ ferrite and austenite is formed during hot rolling heating. Edge seam wrinkles are likely to occur due to ⁇ ferrite at this time, and a polishing thickness exceeding the edge seam wrinkle depth is required in the polishing process after quenching of the disc brake, which hinders productivity.
  • the ⁇ ferrite fraction of the slab during hot rolling can be measured by a phase diagram calculation method or a heat treatment test in a laboratory.
  • the austenite phase is easily distinguished from the martensite structure, and the ⁇ ferrite phase is easily distinguished as a ⁇ ferrite phase with less strain.
  • the hot-rolled steel strip wound after finishing hot rolling has a low toughness because it includes a martensitic structure in which austenite is transformed, and is difficult to rewind as it is.
  • the hot-rolled sheet annealing was performed in a box annealing furnace and the martensite was tempered into ferrite and carbide, it was possible to rewind, but the hot-rolled sheet structure before annealing could not be investigated. After hot rolling annealing, as shown in FIG. 3, it was a structure of ferrite and carbide, and the ⁇ ferrite fraction could not be measured.
  • the present inventors examined a method of examining the ⁇ ferrite fraction in the ferrite matrix in a hot rolled annealed steel sheet of low C martensitic stainless steel.
  • ⁇ ferrite can be colored by Murakami reagent.
  • Murakami's reagent is an aqueous solution of potassium ferricyanide, which is etched by heating the liquid and immersing the sample in it.
  • it is used to distinguish between austenite and ⁇ ferrite phase by coloring ⁇ ferrite mixed in the austenite matrix like the solidification structure of austenitic stainless steel.
  • ⁇ ferrite could be identified in a hot-rolled annealed steel sheet of martensitic stainless steel in which ⁇ ferrite and ferrite were mixed, it could be clearly identified as shown in FIG.
  • the gray contrast portion in FIG. 4 is the ⁇ ferrite portion.
  • the mechanism by which ⁇ ferrite is colored and identified by Murakami's reagent is not clear.
  • the Cr concentration in the ⁇ ferrite phase and the austenite phase (martensite phase at room temperature) during hot rolling is about 1 It is estimated that the high Cr ⁇ ferrite phase was colored and identified by the Murakami reagent because of a difference of 5%.
  • FIG. 5 shows the relationship between the edge seam wrinkle and the amount of ⁇ ferrite, but no edge seam wrinkle was observed in the austenitic stainless steel having a ⁇ ferrite fraction of 0%.
  • the depth of the seam ridge increases as the ⁇ ferrite fraction increases, but the increase in the seam ridge depth is small up to a ⁇ ferrite fraction of 30%. However, it can be seen that when the ⁇ ferrite fraction exceeds 30%, the seam depth increases rapidly.
  • Fig. 6 shows the end of a steel hot rolled ( ⁇ ferrite fraction 4%, 20% (11% Cr, 12% Cr) -0.04% C-1.4% Mn-0.03% N steel). Although the shape of the part is shown, remarkable ear cracking occurs when the ⁇ ferrite fraction decreases.
  • the ⁇ ferrite fraction has a strong correlation with the edge seam flaw depth and ear cracks at the width end of the steel plate, and the martensitic stainless steel with a controlled ⁇ ferrite fraction is used.
  • the edge seam wrinkle depth is shallow, so that it is possible to reduce the grinding depth in the brake disk manufacturing process, thereby improving the productivity of the brake disk.
  • the end of the steel plate can be used, the yield is improved.
  • the present inventors have conducted a detailed study on the amount of ⁇ ferrite, hot-rolling operation conditions, and chemical composition of the hot-rolled annealed steel sheet, achieving both surface quality and ear cracks, and the hardness and corrosion resistance required for disc brakes.
  • an effective method has been found. That is, (1) the amount of ⁇ ferrite during hot rolling heating and (2) component adjustment that satisfies various characteristics, and (3) due to the temperature drop during rough rolling out of the hot rolling heating furnace
  • the present invention has been made on the basis of these findings, and is a means for solving the problems of the present invention, that is, martensitic stainless steel for a motorcycle brake disk according to the present invention (hot rolled steel sheet (hot-rolled annealing is performed). No), including hot-rolled annealed steel sheet) and its manufacturing method is as follows.
  • DFE 12 (Cr + Si) -430C-460N-20Ni-7Mn-89
  • Cr, Si, C, N, Ni, and Mn are the content of each element ( Mass%).
  • the martensitic stainless steel for a motorcycle brake disc according to the present invention further comprising one or two of Ti: 0.03% or less and B: 0.0050% or less in mass%.
  • the martensitic stainless steel for a motorcycle brake disk according to the present invention further comprising one or two of Sn: 0.1% or less and Bi: 0.2% or less in mass%. .
  • the structure and composition control technology of the present invention it is possible to obtain a hot-rolled steel sheet and a hot-rolled annealed steel sheet for a motorcycle brake disk that reduce edge seam wrinkles at the width end of the hot-rolled steel strip and prevent ear cracks at the width end. It becomes possible.
  • the quality is preferable from the viewpoint of improving the productivity and yield of brake discs.
  • edge seam flaw in the width variety edge part of the hot rolled annealing steel strip of martensitic steel for brake discs is shown.
  • a steel ingot of 300 L ⁇ 180 w ⁇ 80 t (mm) cast in a laboratory is rolled to a thickness of 20 mm with a laboratory hot rolling mill, and a width end face is observed.
  • the structure after hot-rolling annealing (where ferrite grain boundaries and carbides are mainly revealed), which is an 11% Cr-1% Mn-0.04% C-0.04% N steel hot-rolled annealing plate It is a photograph which shows a general cross-sectional structure. This is a short-time etching with aqua regia. 11% Cr-1% Mn-0.04% C-0.04% N Martensitic stainless steel hot-rolled annealed steel strip with TD ferrite distribution in the TD cross section where no edge seam flaws or ear cracks were observed This is a photograph (edge seam wrinkle, ⁇ ferrite structure of hot-rolled annealed plate with good ear cracking quality).
  • Martensitic stainless steel grades for motorcycle disc brakes are hot rolled to a thickness of 3.8 mm after changing the hot rolling heating temperature from 1100 to 1280 ° C, and after hot rolling annealing, It is the figure which expand
  • 11-12% Cr-0.04% C-0.5-1.4% Mn-0.03% N steel lab 50mm thick steel ingot is heated to 1250 ° C in the lab and hot rolled to 3mm thickness
  • FIG. 6 is a photograph in which the relationship between the amount of ⁇ ferrite affecting the edge cracks on the end face is examined.
  • C 0.025 to 0.080% C is an essential element for obtaining a predetermined hardness after quenching, and is added in combination with N so as to obtain a predetermined hardness level.
  • the upper limit is made 0.080% in the present invention. It is because hardness will be too hard when added exceeding this, and malfunctions, such as a squeal of a brake and a toughness fall, will be produced.
  • the upper limit of the C content is preferably 0.060% from the viewpoint of hardness control and corrosion resistance improvement.
  • the C content is less than 0.025%, N must be excessively added to obtain hardness, so 0.025% is made the lower limit of the C content. From the viewpoint of the stability of quenching hardness, it is desirable to set it to 0.040% or more.
  • Si 0.05% to 0.8% Si is necessary for deoxidation at the time of melting and refining, and is also useful for suppressing the formation of oxide scale during quenching heat treatment, and the effect is manifested at 0.05% or more. 0.05% or more.
  • Si is mixed from a raw material such as hot metal, an excessive decrease leads to an increase in cost. Further, Si narrows the austenite single phase temperature range and impairs the quenching stability, so that the Si content is set to 0.8% or less. In order to reduce the addition amount of the austenite stabilizing element and reduce the cost, 0.6% or less is desirable.
  • Mn 0.5 to 1.5%
  • Mn is an element added as a deoxidizer, and contributes to improving the hardenability by expanding the austenite single phase region. Since the effect clearly appears at 0.5% or more, the Mn content is set to 0.5% or more. In order to ensure the hardenability stably, it is desirable to make it 1.1% or more. However, Mn promotes the generation of oxide scale during quenching heating and increases the subsequent polishing load. Therefore, the upper limit of the Mn content is set to 1.5% or less. Considering a decrease in corrosion resistance due to granulated materials such as MnS, 1.3% or less is desirable.
  • P 0.035% or less
  • P is an element contained as an impurity in main raw materials such as hot metal and ferrochrome. Since it is an element harmful to toughness after quenching of the hot-rolled annealed sheet, the P content is set to 0.035% or less. In addition, Preferably it is 0.030% or less. Since excessive reduction leads to an increase in cost, such as making it necessary to use a high-purity raw material, the lower limit of P is preferably 0.010%.
  • S 0.015% or less S forms sulfide inclusions and degrades general corrosion resistance (full corrosion and pitting corrosion) of steel materials, and S decreases hot workability and hot rolled steel sheets.
  • the upper limit of the S content is preferably small, and the S content upper limit is set to 0.015%. A more preferable upper limit is 0.008%. Further, the smaller the S content, the better the corrosion resistance. However, since the desulfurization load increases and the production cost increases for lowering the S content, the lower limit is preferably made 0.001%.
  • Cr 11.0-13.5%
  • Cr is an essential element for ensuring oxidation resistance and corrosion resistance. If the Cr content is less than 11.0%, these effects are not exhibited. On the other hand, if the Cr content exceeds 13.5%, the austenite single phase region is reduced and the hardenability is impaired. 11.0 to 13.5%. In consideration of the stability of corrosion resistance, the Cr content is desirably 12.0% or more. In consideration of press formability, the Cr content is desirably 13.0% or less.
  • Ni 0.01 to 0.50%
  • Ni is mixed as an inevitable impurity in the ferritic stainless steel alloy raw material, and is generally contained in the range of 0.01 to 0.10%.
  • the lower limit of Ni content is 0.03%.
  • the upper limit of the Ni content is 0.50%.
  • the Ni content is preferably 0.15% or less.
  • Cu 0.01 to 0.08% Cu is effective in improving the corrosion resistance of the martensite structure containing ⁇ ferrite, and the effect is manifested at 0.01% or more.
  • the austenite stabilizing element is positively added to improve hardenability.
  • the upper limit of the Cu content In consideration of the occurrence of acid rain and the like, the lower limit of the Cu content is preferably 0.02% or more. Further, considering the press formability of the hot-rolled sheet fired steel sheet, 0.08% or less is preferable.
  • Mo 0.01-0.30% Mo is effective for improving the corrosion resistance of the martensite structure containing ⁇ ferrite, and the effect is manifested at 0.01% or more, so the lower limit of the Mo content is set to 0.01%. 0.02% or more is preferable because it is effective for improving the hardenability and improving the heat resistance after quenching.
  • the steel may be tempered by heating after quenching, resulting in a decrease in hardness.
  • the improvement in heat resistance after quenching means that the hardness reduction margin is small. Also called temper softening resistance.
  • the disc brake is used by quenching, but the disc material is heated by resistance heat generated by braking during use. This characteristic is therefore important.
  • Mo is a ferrite phase stabilizing element, and excessive addition impairs the quenching characteristics by narrowing the austenite single phase temperature range, so the upper limit of the Mo content is 0.30% or less.
  • Nb 0.05 to 0.20%
  • Mo 0.05 to 0.20%
  • Nb 0.05 to 0.20% are particularly preferable ranges. is there.
  • V 0.01 to 0.10%
  • V is generally contained in the range of 0.01 to 0.10% because it is mixed as an inevitable impurity in the ferritic stainless steel alloy raw material and is difficult to remove in the refining process.
  • V is an element that forms fine carbonitrides and improves the wear resistance of the brake disk and also has an effect of improving the corrosion resistance. Therefore, V is intentionally added as necessary. . Since the effect is stably exhibited by addition of 0.02% or more, the V content lower limit is preferably 0.02%. 0.03% or more is more desirable. On the other hand, if added excessively, the precipitates may be coarsened. As a result, the toughness after quenching is lowered, so the V content upper limit is made 0.10%. In view of manufacturing cost and manufacturability, the V content is preferably 0.08% or less.
  • Al 0.05% or less
  • Al is an element that improves oxidation resistance in addition to being added as a deoxidizing element. Since the effect is obtained at 0.001% or more, the lower limit of the Al content is preferably set to 0.001% or more.
  • the upper limit of the Al content is set to 0.05% because the toughness of the brake disk is impaired by solid solution strengthening and the formation of large oxide inclusions. Preferably it is 0.03% or less. Al may not be contained.
  • N 0.015 to 0.060%
  • N is one of the very important elements in the present invention. Like C, it is an essential element for obtaining a predetermined hardness after quenching, and is added in combination with C so as to obtain a predetermined hardness level.
  • precipitation of Cr carbide that is, sensitization phenomenon is likely to occur and corrosion resistance may be reduced, but nitrogen suppresses precipitation of Cr carbide and has corrosion resistance. The improvement effect may be shown. Since the effect is manifested at 0.015% or more, the N content is set to 0.015% or more.
  • the N content is preferably 0.030% or more. Moreover, it is desirable to make it into the range of 0.050% or less.
  • the amount of ⁇ ferrite ( ⁇ ferrite fraction) observed in the hot-rolled steel sheet or hot-rolled annealed steel sheet is 5% or more and 30% or less in terms of area ratio.
  • the amount of ⁇ ferrite in the steel affects edge seam defects and hot-ear cracks during hot rolling. If the ⁇ ferrite fraction is less than 5%, the hot workability deteriorates and the ear cracks are liable to occur. On the other hand, when the ⁇ ferrite fraction exceeds 30%, edge seam wrinkles are likely to occur due to the coarsening of the crystal grain size, and in the polishing process after quenching the brake disk, a large grinding thickness is used to remove the edge seam wrinkles. Therefore, the ⁇ ferrite fraction should be 30% or less.
  • ⁇ ferrite during hot rolling is observed in the cross section of the hot rolled annealed steel sheet and hot rolled steel sheet, and is evaluated by ordinary microscopic observation.
  • the structure etching of ⁇ ferrite is performed by Murakami reagent (potassium ferricyanide). It is desirable to immerse the sample in a heated solution.
  • the following elements can be added in order to improve weather resistance, heat resistance, hot workability, and the like.
  • Ti 0.03% or less
  • Ti is an element that suppresses deterioration of sensitization and corrosion resistance due to precipitation of chromium carbonitride in stainless steel by forming carbonitride.
  • the Ti content is preferably 0.001% or more.
  • the upper limit of the Ti content is 0.03% or less. Considering toughness in winter, it is desirable to make it 0.01% or less. Ti may not be contained.
  • B 0.0050% or less
  • B is an element effective for improving hot workability, and its effect is manifested at 0.0002% or more. Therefore, B may be added at 0.0002% or more.
  • the content is preferably 0.0010% or more.
  • 0.0050% is made the B content upper limit. In consideration of corrosion resistance, 0.0025% or less is desirable.
  • Nb 0.3% or less
  • Nb is an element that suppresses deterioration of sensitization and corrosion resistance due to precipitation of chromium carbonitride in stainless steel by forming carbonitride.
  • Nb content is preferably 0.001% or more.
  • the heat resistance is also referred to as the degree of resistance to softening when subjected to heat after quenching, that is, the temper softening resistance.
  • NbN is added excessively, formation of NbN in the brake disc causes a decrease in toughness and squeal, which is not preferable, and 0.3% is made the upper limit of the Nb content.
  • Sn 0.1% or less Sn is an element effective for improving the corrosion resistance after quenching, and is preferably 0.001% or more, and preferably 0.02% or more if necessary. However, excessive addition promotes ear cracking during hot rolling, so it is preferably made 0.10% or less.
  • Bi 0.2% or less Bi is an element that improves corrosion resistance. Although the mechanism is not clarified, it is believed that MnS, which is likely to become a starting point, has an effect of miniaturization by adding Bi, and therefore the probability of becoming a starting point is lowered. The effect is exhibited by adding 0.01% or more of Bi. Even if added over 0.2%, the effect is only saturated, so the upper limit of Bi content is set to 0.2%.
  • an impurity element is contained within a range not impairing the effects of the present invention. It is preferable to reduce as much as possible Zn, Pb, Se, Sb, H, Ga, Ta, Ca, Mg, Zr, etc. as well as the above-mentioned general impurity elements P and S.
  • the content ratio of these elements is controlled within the limits of solving the problems of the present invention, and the content is Zn ⁇ 100 ppm, Pb ⁇ 100 ppm, Se ⁇ 100 ppm, Sb ⁇ 500 ppm, H ⁇ 100 ppm, Ga ⁇ 500 ppm, Ta ⁇ 500 ppm, Ca ⁇ 120 ppm, Mg ⁇ 120 ppm, Zr ⁇ 120 ppm.
  • the hot rolling step it is preferable to heat a rough bar having a thickness of 20 to 40 mm between 10 ° C. and 50 ° C. using an induction heating device (bar heater) between rough rolling and finish rolling.
  • an induction heating device bar heater
  • the heating temperature of the coarse bar is less than 10 ° C., the amount of ⁇ ferrite is small, and ear cracks are likely to occur due to a decrease in hot workability.
  • the heating temperature exceeds 50 ° C. the amount of ⁇ ferrite becomes too large, the crystal grain size becomes coarse, the rough surface of the rough bar end face becomes large, and deep edge seams are likely to occur. Even if the slab heating temperature is increased without heating with the coarse bar heater, the temperature of the coarse bar increases.
  • the hot rolling heating temperature is preferably 1250 ° C. or lower.
  • the hot rolling heating temperature is less than 1150 ° C., the deformation resistance concentrates in a small amount of ⁇ ferrite phase due to an increase in deformation resistance of the austenite matrix phase and a decrease in the amount of ⁇ ferrite. Since this occurs and the yield decreases, the hot rolling heating temperature is desirably 1150 ° C. or higher.
  • the quality specified in each claim can be realized by having the components and the ⁇ ferrite fraction described in each claim.
  • the martensitic stainless steel for motorcycle brake discs of the present invention can exhibit an effect in both hot-rolled steel sheets and hot-rolled annealed steel sheets that are not subjected to hot-roll annealing.
  • steels having the component compositions shown in Table 1-1 and Table 1-2 were melted and cast into slabs having a thickness of 200 mm. This slab was heated to 1150 to 1250 ° C., then subjected to rough hot rolling and finish hot rolling to obtain a hot-rolled steel plate having a thickness of 4 mm and wound in a temperature range of 750 to 900 ° C. Between rough hot rolling and finish rolling, a rough bar heater using induction heating was used, and heating was performed at a temperature rise condition of 10 to 50 ° C. The hot-rolled steel sheet was subsequently annealed in a box-type annealing furnace with respect to the hot-rolled coil. The maximum heating temperature was set to a temperature range of 800 ° C.
  • the cross-sectional structure was observed using an optical microscope, and the amount of ⁇ ferrite was measured by image analysis.
  • Murakami reagent was used for the appearance of ⁇ ferrite.
  • the JIS surface hardness (quenching hardness) is evaluated with a Rockwell hardness meter C scale, less than 32 Was rejected (B), and 32 or more was determined to be acceptable (A). Further, a test at a tempering temperature of 530 ° C. was performed in the same manner, and 32 or higher was accepted (S), and entered in the “Temper softening resistance” column of Tables 2-1, 2-2, and 2-3.
  • Corrosion resistance was evaluated by finishing the surface of hot-rolled annealed pickled plate with # 600, followed by a salt spray test for 4 hours (JIS Z 2371 “Salt spray test method”), measuring the rust area ratio, and rust area ratio of 10 % Or more was rejected (B), and less than that was determined to be pass (A). In particular, those having a rust area ratio of zero were regarded as acceptable (S).
  • the depth of the edge seam wrinkles was 150 ⁇ m or less as pass (A), and over 150 ⁇ m was rejected (B).
  • the component composition to which the present invention is applied, and the ⁇ ferrite area ratio is 5% or more and 30% or less.
  • the quality of the edge seam wrinkles was acceptable, the ear cracking quality was also acceptable, and the quenching hardness, heat resistance, and corrosion resistance were also good.
  • the heating temperature of the coarse bar by the coarse bar heater is within the range of the present invention, the depth of the edge seam wrinkles is further reduced, and the polishing time of the disc after quenching can be shortened.
  • the ear cracking quality was further improved and was no longer recognized.
  • test no. Nos. 38 and 56 are high in C and N. Since C and N were low in Nos. 42 and 55, the quenching hardness was outside the target range. NO. No. 40 is low in Si. No. 54 had poor polishability in the polishing step after quenching because of high V. No. 41, 42, 45, 46, 57, 58, 59, 60, 61, 62 had poor edge seam flaw quality or ear crack rating because the amount of ⁇ ferrite of hot-rolled annealed plate was more than 30% or less than 5% Met. No. No. 43 has a high P. No. 44 has a high S. No. 50 had a poor ear crack rating because Cu was high.
  • the martensitic stainless steel plate for brake discs of the present invention is optimized for the amount of ⁇ ferrite observed in hot-rolled and annealed steel plates and hot-rolled steel plates, and controls component design and hot rolling conditions.
  • good edge seam wrinkle quality and ear cracking quality are obtained, and a high-quality brake disc without deterioration in hardness and corrosion resistance after quenching is obtained.
  • the edge seam wrinkle quality and the ear crack quality were further improved by heating the rough bar between the rough hot rolling and the finish hot rolling under the optimum conditions according to the composition.

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  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

　L'invention concerne un acier inoxydable martensitique destiné à être utilisé dans un disque de frein de véhicule à deux roues, ledit acier étant caractérisé en ce qu'il contient 0,025 à 0,080 % de C, 0,05 à 0,8 % de Si, 0,5 à 1,5 % de Mn, pas plus de 0,035 % de P, pas plus de 0,015 % de S, 11,0 à 13,5 % de Cr, 0,01 à 0,50 % de Ni, 0,01 à 0,08 % de Cu, 0,01 à 0,30 % de Mo, 0,01 à 0,10 % de V, pas plus de 0,05 % d'Al, et 0,015 à 0,060 % de N (tous les pourcentages étant donnés par rapport à la masse); ledit acier ayant une valeur DFE de 5 à 30 (inclus) (DFE = 12 (Cr + Si)－430C－460N－20 Ni－7 Mn－89 (formule 1)) ; et ayant une teneur en ferrite delta observée dans la structure de section transversale de 5 à 30 % (inclus) par zone. Ti, B, Nb, Sn ou Bi peuvent être ajoutés.
PCT/JP2015/074912 2014-09-17 2015-09-02 Acier inoxydable martensitique pour disque de frein et procédé de fabrication dudit acier WO2016043050A1 (fr)

Priority Applications (2)

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CN201580050329.1A CN107075630B (zh) 2014-09-17 2015-09-02 制动盘用马氏体系不锈钢及其制造方法
US15/511,905 US20170253945A1 (en) 2014-09-17 2015-09-02 Martensitic stainless steel for brake disk and method for producing said steel

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JP2014-188401 2014-09-17
JP2014188401 2014-09-17
JP2015-062216 2015-03-25
JP2015062216A JP6417252B2 (ja) 2014-09-17 2015-03-25 ブレーキディスク用マルテンサイト系ステンレス鋼とその製造方法

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CN111304556A (zh) * 2020-04-03 2020-06-19 北京机科国创轻量化科学研究院有限公司 一种含mc、mx型析出相高速列车制动盘铸钢及制备方法

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JP2005133204A (ja) * 2003-10-08 2005-05-26 Jfe Steel Kk 耐焼戻し軟化性に優れるブレーキディスクおよびその製造方法
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JP2010215995A (ja) * 2009-03-19 2010-09-30 Nippon Steel & Sumikin Stainless Steel Corp 耐食性に優れたマルテンサイト系ステンレス鋼
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WO2012157680A1 (fr) * 2011-05-16 2012-11-22 新日鐵住金ステンレス株式会社 Plaque en acier inoxydable martensitique pour rotor de frein à disque d'automobile et procédé de fabrication associé

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JP2002121656A (ja) * 2000-10-18 2002-04-26 Sumitomo Metal Ind Ltd ディスクブレ−キロ−タ−用ステンレス鋼
JP2005133204A (ja) * 2003-10-08 2005-05-26 Jfe Steel Kk 耐焼戻し軟化性に優れるブレーキディスクおよびその製造方法
JP2005307346A (ja) * 2004-03-22 2005-11-04 Jfe Steel Kk 耐熱性と耐食性に優れるディスクブレーキ用ステンレス鋼板
JP2006291240A (ja) * 2005-04-06 2006-10-26 Jfe Steel Kk 焼戻し軟化抵抗と靭性に優れるブレーキディスク
JP2009132973A (ja) * 2007-11-30 2009-06-18 Jfe Steel Corp 打ち抜き加工性に優れたマルテンサイト系ステンレス鋼板の製造方法
JP2009256787A (ja) * 2008-03-27 2009-11-05 Nippon Steel & Sumikin Stainless Steel Corp 耐銹性に優れたディスクブレーキ用マルテンサイト系ステンレス鋼
JP2010215995A (ja) * 2009-03-19 2010-09-30 Nippon Steel & Sumikin Stainless Steel Corp 耐食性に優れたマルテンサイト系ステンレス鋼
JP2011012343A (ja) * 2009-06-01 2011-01-20 Jfe Steel Corp ブレーキディスク用鋼板およびブレーキディスク
WO2012157680A1 (fr) * 2011-05-16 2012-11-22 新日鐵住金ステンレス株式会社 Plaque en acier inoxydable martensitique pour rotor de frein à disque d'automobile et procédé de fabrication associé

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111304556A (zh) * 2020-04-03 2020-06-19 北京机科国创轻量化科学研究院有限公司 一种含mc、mx型析出相高速列车制动盘铸钢及制备方法

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