WO2009087990A1 - Wear-resistant steel sheet having excellent wear resistant at high temperature and processability upon bending, and method for production thereof - Google Patents

Wear-resistant steel sheet having excellent wear resistant at high temperature and processability upon bending, and method for production thereof Download PDF

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Publication number
WO2009087990A1
WO2009087990A1 PCT/JP2009/050024 JP2009050024W WO2009087990A1 WO 2009087990 A1 WO2009087990 A1 WO 2009087990A1 JP 2009050024 W JP2009050024 W JP 2009050024W WO 2009087990 A1 WO2009087990 A1 WO 2009087990A1
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wear
wear resistance
temperature
resistant steel
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PCT/JP2009/050024
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French (fr)
Japanese (ja)
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Tatsuya Kumagai
Naoki Saitoh
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Nippon Steel Corporation
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Priority to JP2009509198A priority Critical patent/JP4590012B2/en
Priority to US12/532,032 priority patent/US20100139820A1/en
Priority to EP09700890.8A priority patent/EP2180076B1/en
Priority to BRPI0901014-9A priority patent/BRPI0901014A2/en
Priority to AU2009203476A priority patent/AU2009203476B2/en
Priority to CN2009800000615A priority patent/CN101680071B/en
Publication of WO2009087990A1 publication Critical patent/WO2009087990A1/en

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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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • 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
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum

Definitions

  • the present invention relates to a wear-resistant steel plate excellent in high-temperature wear resistance and bending workability used for construction machinery and industrial machinery, and a method for producing the same.
  • wear resistant steel of the HB500 class (with a Brinell hardness of about 450 to 550 at room temperature) is excellent in wear resistance but not very good in bending workability.
  • Wear resistant steel of HB400 class (with Brinell hardness of about 360 to 440 at room temperature) with lower hardness can be bent relatively easily, and is applied to many parts that require processing. Abrasion resistance, particularly in high temperature environments, is not sufficient.
  • steel sheets for wear-resistant applications do not require a particularly high toughness value, but a certain toughness value is set so that cracks do not occur even if the thickness of the steel sheet decreases during use. It is necessary to have. Even considering use in cold regions, it is considered that Charpy absorbed energy at ⁇ 40 ° C. is 27 J or more.
  • Patent Document 1 as a wear-resistant steel for high-temperature applications of Brinell hardness HB500 class.
  • the invention described in this document is designed with the highest priority on high temperature wear resistance, and does not take any special measures to improve the bending workability, and is therefore limited to applications where the bending radius is relatively gentle. .
  • Patent Document 2 relates to wear resistant steel for medium and normal temperatures used in a region where the temperature is changed from 300 ° C to 400 ° C.
  • toughness and workability are not taken into consideration and their characteristics are not shown, but because Si is very high, toughness is not high and workability is not high.
  • Patent Document 3 relates to HB400 class wear-resistant steel having excellent bending workability, but no consideration is given to wear resistance in a high-temperature environment.
  • the HB400 class wear-resistant steel having good bending workability and the wear-resistant steel plate having high wear resistance even in a high temperature environment from 300 ° C. to 400 ° C. are suitable so far. I can't find it.
  • the wear-resistant steel plate is a consumable item, economic efficiency is also an important factor, and it is desirable that the amount of expensive alloy elements added be as low as possible.
  • the present invention is a wear-resistant steel that is HB400 class room temperature hardness with good bending workability and has high wear resistance even in a high temperature environment of 300 ° C. to 400 ° C., and is also excellent in economy.
  • the purpose is to provide.
  • the present invention assumes a high temperature environment of 300 ° C. to 400 ° C., but the typical temperature for characteristic evaluation is set to 350 ° C., and the martensitic steel having various chemical compositions at 350 ° C.
  • the wear resistance was investigated.
  • the abrasion resistance evaluation was performed as follows. In a pin-on-disk type wear test device compliant with ASTM G99-05, the sample temperature is controlled so that the sample temperature is 350 ° C., and the wear amount of the test sample and the standard sample (SS400) is determined. It was measured. Then, using SS400 as a standard sample, [wear amount of SS400 / wear amount of test sample] was defined as a 350 ° C. wear resistance ratio, and this 350 ° C. wear resistance ratio was determined. It can be said that the larger this value, the better the wear resistance at 350 ° C.
  • FIG. 1 shows 0.15% C-0.57% Si-0.41% Mn-1.37% Cr-0.08% Mo-0.012% Ti-0.0011% B-0.0032% This is the relationship between the Nb addition amount and the 350 ° C. wear resistance ratio of martensitic steel with N as the basic composition and the Nb amount varied.
  • the Nb addition amount is 0 to 0.03%, the 350 ° C. wear resistance ratio does not change much, but when the Nb addition amount exceeds 0.03%, the 350 ° C. wear resistance ratio is greatly improved.
  • Nb carbonitride precipitated during rolling suppresses recrystallization and refines the structure, Nb is usually added in an amount of 0.01 to 0.02% for this purpose.
  • Nb carbonitride deposited during rolling does not contribute much to high temperature hardness.
  • Nb existing in a solid solution state in the steel sheet remains in a solid solution state at 300 ° C. to 400 ° C. or exists as a very fine carbonitride, and any of them contributes to an improvement in high temperature hardness. Inferred. That is, when the steel sheet is heated to 350 ° C. by adding Nb in an amount that greatly exceeds the amount precipitated during rolling and by increasing the solid solution Nb in the steel sheet by selecting appropriate rolling and cooling conditions. It is considered that the hardness can be increased, and as a result, the 350 ° C. wear resistance can be improved.
  • the inventors have analyzed in detail the relationship between the alloying elements and the 350 ° C. wear resistance of a larger number of martensitic steels having an HB in the range of 360 to 440 at 25 ° C. As a result, the following formula (1) for predicting the 350 ° C. wear resistance ratio from the chemical composition was derived.
  • FIG. 2 shows the relationship between HI and the 350 ° C. wear resistance ratio of martensitic steel.
  • the target value of the high temperature wear resistance in the present invention is set such that the 350 ° C. wear resistance ratio is 3.0 or more, that is, the wear loss is 1/3 or less of SS400.
  • HI should be 0.7 or more.
  • the wear resistance ratio is 4.0 or more, and a better wear resistance can be obtained.
  • the applied plate thickness of wear-resistant steel is often up to 50 mm. If the following Ceq is more than 0.50, it is possible to ensure hardenability sufficient to obtain a martensite structure up to the center of a steel plate having a thickness of 50 mm.
  • Ceq [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14
  • [C], [Si], [Mn], [Ni], [Cr], [Mo], and [V] contain C, Si, Mn, Ni, Cr, Mo, and V, respectively. Amount (% by mass).
  • the wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability according to the present invention is in mass%, C: 0.13% or more, 0.18% or less, Si: 0.5% or more, 1.0 %, Mn: 0.2% or more, 0.8% or less, P: 0.020% or less, S: 0.010% or less, Cr: 0.5% or more, 2.0% or less, Mo: 0 0.03% or more, 0.30% or less, Nb: more than 0.03%, 0.10% or less, Al: 0.01% or more, 0.20% or less, B: 0.0005% or more, 0.0030 %, N: 0.010% or less, Fe and unavoidable impurities as the balance, the composition of the following HI is 0.7 or more, and Ceq is more than 0.50 And HB (Brinell hardness) is 360 or more and 440 or less at 25 ° C.
  • the method for producing a wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability comprises heating a steel slab or slab having the composition described in (1) or (2) above 1200 ° C.
  • the hot rolling is performed at a cumulative reduction ratio of 30% or more and 65% or less at 960 ° C. or lower and 900 ° C. or higher, and the hot rolling is finished at 900 ° C. or higher.
  • the present invention has HB400 class room temperature hardness with good bending workability, and has high wear resistance even in a high temperature environment from 300 ° C. to 400 ° C., and is also excellent in economic efficiency.
  • a wear-resistant steel plate can be easily manufactured.
  • FIG. 1 is a graph showing the relationship between the amount of Nb added and the wear resistance at 350.degree.
  • FIG. 2 is a graph showing the relationship between HI and wear resistance at 350 ° C.
  • C is an important element that determines the hardness of martensite.
  • the C range is 0.13% or more and 0.18% or less in order to set the room temperature HB at the center of the plate thickness up to 50 mm to 360 to 440.
  • Si is an element particularly effective for improving the 350 ° C. wear resistance, and the alloy price is also low.
  • addition of a large amount of Si reduces toughness and processability.
  • the Si addition amount is set to 0.50% or more and less than 1.0%. In the case where workability is more important, the Si addition amount is desirably less than 0.8%.
  • Mn is essential in order to avoid a decrease in toughness and bending workability due to segregation of grain boundaries of S by forming MnS, and 0.2% or more is added. Since Mn improves hardenability, it is better to add Mn in order to ensure the normal temperature hardness at the center of the plate thickness up to 50 mm. However, on the other hand, Mn lowers the high-temperature strength, so it rather lowers the 350 ° C. wear resistance. For this reason, the amount of Mn added is desirably less than 0.5%. For the purpose of improving hardenability, the upper limit is made 0.8%. Therefore, the amount of Mn added is 0.2% or more and 0.8% or less, desirably 0.2% or more and less than 0.5%.
  • P P is an inevitable impurity and is a harmful element that reduces bending workability and toughness. Therefore, the content is suppressed to 0.020% or less. More desirably, the content is 0.010% or less.
  • P is preferably as low as possible for bending workability and toughness, but an increase in refining cost is inevitable in order to reduce it to less than 0.0005%. Therefore, it is necessary to limit P to such a very low level. Absent.
  • S is also an inevitable impurity and is a harmful element that reduces bending workability and toughness. Therefore, the content is suppressed to 0.010% or less. More preferably, it is made 0.005% or less. S is preferably as low as possible for bending workability and toughness, but an increase in refining cost is inevitable in order to reduce it to less than 0.0005%, so it is necessary to limit it to such a very low level. Absent.
  • Cr is effective in improving hardenability and improving 350 ° C. wear resistance, so is added at least 0.5% or more.
  • the addition amount is desirably 1.0% or more.
  • the toughness may be lowered, so the content is made 2.0% or less.
  • Mo improves the wear resistance at 350 ° C. and, in the presence of Nb, has the effect of greatly increasing the hardenability by adding a small amount. Therefore, addition of 0.03% or more is essential. However, if excessively added, the toughness may be lowered, so the upper limit of the amount of Mo added is 0.30%. Moreover, Mo is very expensive in recent years, and the addition amount is preferably less than 0.10% from the viewpoint of suppressing alloy costs.
  • Nb is very effective in improving the 350 ° C. wear resistance because it exists in a solid solution state in the steel sheet.
  • the amount of Nb added to ensure sufficient solute Nb is more than 0.03%, and more preferably 0.04% or more.
  • Nb (CN) may not be sufficiently dissolved at the time of heating if the amount of Nb is large. Such undissolved Nb does not contribute to improving the high temperature hardness and may cause a decrease in toughness. Therefore, the Nb addition amount is set to 0.10% or less, and more desirably 0.08% or less.
  • Al is added in an amount of 0.01% or more as a deoxidation element or inclusion form control element. Moreover, in order to secure the free B necessary for improving the hardenability, 0.05% or more is added for the purpose of fixing N. In either case, excessive addition may reduce toughness, so the upper limit is made 0.20%, preferably 0.10%.
  • B is an essential element that is very effective for improving hardenability. In order to exert the effect, 0.0005% or more is necessary, but if added over 0.0030%, weldability and toughness may be lowered, so the B content is 0.0005% or more, 0 0030% or less.
  • N When N is excessively contained, the toughness is reduced, and BN is formed to inhibit the effect of improving the hardenability of B, so the content is suppressed to 0.010% or less. More desirably, it is 0.006% or less. N is preferably as low as possible in order to avoid toughness and BN formation, but in order to reduce it to less than 0.001%, an increase in refining cost is inevitable, so it is necessary to limit to such a very low level. Absent.
  • Cu is an element that can improve hardness without reducing toughness, and may be added in an amount of 0.05% or more for that purpose. However, if too much Cu is added, the toughness may be lowered, so the addition amount is 1.5% or less.
  • Ni is an effective element for improving toughness, and 0.05% or more may be added for the purpose. However, since Ni is an expensive element, the addition is made 1.0% or less.
  • V is an element effective for improving the 350 ° C. wear resistance. For this purpose, 0.01% or more may be added. However, V is also an expensive element, and if added excessively, the toughness may be lowered. Therefore, even when added, the content is made 0.20% or less.
  • Ti may be added so as to prevent formation of BN by fixing N as TiN and to secure free B necessary for improving hardenability. For this purpose, 0.003% or more is added. Added. However, the addition of Ti tends to lower the 350 ° C. wear resistance. Therefore, the amount of Ti added is 0.030% or less.
  • the component composition is limited so that the HI of formula (1) is 0.7 or more and Ceq is more than 0.50. However, if HI or Ceq is too high, the toughness may be lowered. Therefore, it is desirable that HI is 1.2 or less and Ceq is 0.70 or less.
  • the manufacturing method of the wear-resistant steel plate of the present invention will be described.
  • hot rolling is performed by heating a steel slab (slab) or slab having the above steel composition.
  • the method for producing a steel slab or slab prior to hot rolling is not particularly limited.
  • the components are adjusted so that the desired component content is obtained by various secondary scouring, and then, in addition to normal continuous casting, casting by ingot method, thin slab What is necessary is just to cast by methods, such as casting.
  • Scrap may be used as a raw material.
  • a slab obtained by continuous casting it may be directly sent to a hot rolling mill as it is a high-temperature slab, or may be hot-rolled after being reheated in a heating furnace after being cooled to room temperature.
  • the components of the steel slab or slab are the same as the components of the wear-resistant steel plate of the present invention described above.
  • the heating temperature of the steel slab or slab is set to 1200 ° C. or higher so that Nb is sufficiently dissolved. However, if the heating temperature is too high, the austenite structure becomes coarse, and therefore the structure after hot rolling may not be sufficiently refined and the toughness may be lowered. Therefore, the heating temperature of the steel slab or slab is 1350 ° C. or less. Is desirable.
  • the cumulative rolling reduction is set to 30% to 65% at 960 ° C. or lower and 900 ° C. or higher. In order to minimize the precipitation of Nb carbonitride during rolling, it is limited to this temperature and rolling reduction range. Further, in order to avoid unnecessary Nb carbonitride precipitation and leave a large amount of solid solution Nb, the hot rolling is finished at 900 ° C. or higher. Moreover, the end temperature of hot rolling needs to be 960 degrees C or less.
  • accelerated cooling is performed by direct quenching or reheating quenching.
  • direct quenching accelerated cooling is performed immediately after the hot rolling to a temperature of 200 ° C. or less at a cooling rate of 5 ° C./s or more (cooling rate at the center of the plate thickness).
  • reheating and quenching after completion of hot rolling, it is once cooled to a temperature of 200 ° C. or less (the cooling rate at this time is arbitrary), and then reheated to a temperature not lower than the Ac3 transformation point. Accelerated cooling to 200 ° C. or lower so that the cooling rate at the part is 5 ° C./s or higher.
  • the cooling rate in accelerated cooling after completion of hot rolling in the case of direct quenching and in accelerated cooling after reheating in the case of reheating quenching increases as the plate thickness decreases.
  • the target plate thickness is mainly assumed to be about 4.5 mm to 50 mm.
  • the cooling rate at a plate thickness of 4.5 mm may become very large, there is no particular problem, and no upper limit is set for the cooling rate.
  • Tempering heat treatment is not particularly required, but the properties of the steel sheet do not depart from the present invention even if heat treatment is performed at a temperature of 300 ° C. or lower.
  • the wear resistance ratio (SS400) is determined by performing a wear test at a sample temperature of 350 ° C. in a pin-on-disk type wear test apparatus compliant with ASTM G99-05 as described above. Wear amount / wear amount of the test sample).
  • the target value of wear resistance is an abrasion resistance ratio of 3.0 or more. Evaluation of bending workability was performed as follows.
  • the test piece JIS No. 1 was bent 180 degrees in the C direction at a bending radius (4 t) four times the plate thickness, and the outside of the curved portion was observed after the bending test. The test was accepted when no tears or other defects occurred outside the curved portion.
  • the toughness was evaluated as follows. A JIS Z 2201 No. 4 Charpy test piece was sampled perpendicularly to the rolling direction from the center of the plate thickness, and subjected to an impact test at -40 ° C. to measure the absorbed energy value. Then, the average value of the absorbed energy values of the impact test at ⁇ 40 ° C. of the three test pieces was determined. The average value of the toughness target value was set to 27 J or more. The obtained results are shown in Tables 5 and 6. In Tables 1 to 6, the underlined numerical values indicate the component values outside the present invention, those having insufficient temperature conditions and characteristics.
  • the steel plates Nos. 1 to 17 of the inventive examples in Table 5 all satisfy the above-mentioned normal temperature hardness, wear resistance at 350 ° C., bending workability, and toughness target values.
  • the normal temperature hardness is 350 ° C.
  • One or more of the wear resistance, bending workability, and toughness of the steel is less than the target value.
  • the comparative steel plates Nos. 41 to 44 which are steel components of the present invention but deviate from the production method of the present invention, among the normal temperature hardness, wear resistance at 350 ° C., bending workability, and toughness One or more are rejected.
  • a wear-resistant steel sheet having HB400 class room temperature hardness with good bending workability, high wear resistance even in a high temperature environment of 300 ° C. to 400 ° C., and excellent in economic efficiency. Can be easily manufactured. For this reason, it is suitable for components such as bulldozer buckets that generate frictional heat due to strong impacts and sintered coke hoppers that collide with high-temperature objects, such as construction machinery and industrial machinery that require high wear resistance in high-temperature environments. Available.

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  • Engineering & Computer Science (AREA)
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  • Metallurgy (AREA)
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Abstract

Disclosed is a wear-resistant steel sheet comprising the following components (by mass%): C: 0.13 to 0.18% (inclusive); Si: not less than 0.5% and less than 1.0%, Mn: 0.2 to 0.8% (inclusive), P: 0.020% or less, S: 0.010% or less, Cr: 0.5 to 2.0% (inclusive), Mo: 0.03 to 0.30% (inclusive), Nb: more than 0.03% and not more than 0.10%, Al: 0.01 to 0.20% (inclusive), B: 0.0005 to 0.0030% (inclusive), and N: 0.010% or less, with the remainder being Fe and unavoidable impurities, wherein the chemical composition fulfils the requirements that the HI value is 0.7 or more and that the Ceq value is more than 0.50. The steel sheet has an HB (Brinell hardness) value of 360 to 440 (inclusive) at 25˚C.

Description

高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板およびその製造方法Abrasion-resistant steel plate excellent in high-temperature wear resistance and bending workability and manufacturing method thereof
　この発明は、建設機械や産業機械に用いられる高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板およびその製造方法に関する。
　本願は、２００８年１月７日に出願された日本国特許出願第２００８－０００３０１号及び２００８年１０月１７日に出願された日本国特許出願第２００８－２６８２５３号に対し優先権を主張し、その内容をここに援用する。 The present invention relates to a wear-resistant steel plate excellent in high-temperature wear resistance and bending workability used for construction machinery and industrial machinery, and a method for producing the same.
This application claims priority to Japanese Patent Application No. 2008-000301 filed on January 7, 2008 and Japanese Patent Application No. 2008-268253 filed on October 17, 2008. The contents are incorporated here.
　鉱山での掘削や土木作業用の建設機械では、摩耗のために頻繁に交換が必要となる部材が多くある。なかでも鋼材にとって過酷な条件となるのは、高温の環境下で使用される場合である。温度上昇によって耐摩耗鋼は硬さが低下するため、ある温度以上では摩耗速度が急激に大きくなる。特に摩耗が著しいのは、強い衝撃による摩擦熱が生じるブルドーザーのバケットや、高温の物体が衝突する焼結コークスのホッパーなどであり、こうした部材では、部材を構成する鋼板表面の温度が一時的に３００℃から４００℃程度にもなるとされている。頻繁な部材交換は設備稼働率の低下を招くので、このような環境化においても耐摩耗性の高い鋼材（耐摩耗鋼）が要望されることになる。 There are many components that need to be replaced frequently due to wear in construction machines for excavation and civil engineering work in mines. Among them, a severe condition for steel is when it is used in a high temperature environment. As the temperature rises, the wear-resistant steel decreases in hardness, so the wear rate increases rapidly above a certain temperature. The wear is particularly remarkable in bulldozer buckets that generate frictional heat due to strong impacts, and sintered coke hoppers that collide with high-temperature objects. It is supposed to be about 300 ° C to 400 ° C. Since frequent member replacement causes a reduction in equipment operation rate, a steel material having high wear resistance (abrasion resistant steel) is required even in such an environment.
　一方で、いろいろな形状の部位に適用するため、あるいは極力溶接箇所を減らすため、耐摩耗鋼には鋼板の曲げ加工性が重要視されることが多い。 On the other hand, in order to apply to various shapes of parts or to reduce the number of welds as much as possible, bending workability of steel sheets is often regarded as important for wear-resistant steel.
　耐摩耗性の向上には硬さを高くすることが有効である。しかしながら硬さが高い鋼板は、特に曲げ半径の小さな曲げを行ったときに、割れたり、亀裂が入ったりということが起きやすくなる。さらに曲げに対する変形抵抗の大きさや、スプリングバックを考慮すると、鋼板の硬さが高いことは、曲げ加工には不利となる。すなわち、耐摩耗性と曲げ加工性とは一般的には相反する特性である。例えば、ＨＢ５００クラス（常温でのブリネル硬さが４５０～５５０程度）の耐摩耗鋼は、耐摩耗性には優れるが、曲げ加工性はあまり良くない。これより硬さの低いＨＢ４００クラス（常温でのブリネル硬さが３６０～４４０程度）の耐摩耗鋼は、比較的容易に曲げ加工ができるので、加工を要する多くの部材に適用されているが、耐摩耗性、特に高温環境での耐摩耗性は十分とはいえない。 Higher hardness is effective for improving wear resistance. However, a steel sheet having a high hardness is likely to break or crack when it is bent with a small bending radius. Furthermore, considering the magnitude of deformation resistance to bending and springback, the high hardness of the steel sheet is disadvantageous for bending. That is, wear resistance and bending workability are generally contradictory characteristics. For example, wear resistant steel of the HB500 class (with a Brinell hardness of about 450 to 550 at room temperature) is excellent in wear resistance but not very good in bending workability. Wear resistant steel of HB400 class (with Brinell hardness of about 360 to 440 at room temperature) with lower hardness can be bent relatively easily, and is applied to many parts that require processing. Abrasion resistance, particularly in high temperature environments, is not sufficient.
　したがって、曲げ加工性と高温耐摩耗性を両立させるためには、常温硬さがＨＢ４００クラスの耐摩耗鋼に高温耐摩耗性を具備させることが有効な方法であるといえる。 Therefore, in order to achieve both bending workability and high-temperature wear resistance, it can be said that it is an effective method to provide high-temperature wear resistance to wear-resistant steel having a normal temperature hardness of HB400 class.
　一般的に、耐摩耗用途の鋼板には特に高い靭性値が必要とされることはないが、使用中に鋼板の板厚が減少してきても割れが生じることのないよう、一定の靭性値を具備する必要がある。寒冷地での使用を考慮しても、－４０℃でのシャルピー吸収エネルギーが２７Ｊ以上あればよいと考えられる。 In general, steel sheets for wear-resistant applications do not require a particularly high toughness value, but a certain toughness value is set so that cracks do not occur even if the thickness of the steel sheet decreases during use. It is necessary to have. Even considering use in cold regions, it is considered that Charpy absorbed energy at −40 ° C. is 27 J or more.
　本発明者らは、先にブリネル硬さＨＢ５００クラスの高温用途の耐摩耗鋼として、特許文献１を開示した。この文献に記載の発明は、高温耐摩耗性を最優先した設計をしており、曲げ加工性を向上させる特段の対策はとっておらず、そのため比較的曲げ半径がゆるやかな用途に限定される。 The present inventors previously disclosed Patent Document 1 as a wear-resistant steel for high-temperature applications of Brinell hardness HB500 class. The invention described in this document is designed with the highest priority on high temperature wear resistance, and does not take any special measures to improve the bending workability, and is therefore limited to applications where the bending radius is relatively gentle. .
　特許文献２は、３００℃から４００℃になる部位に用いる中常温用の耐摩耗鋼に関するものである。ここでは靭性や加工性については考慮されておらず、それらの特性も示されていないが、Ｓｉが非常に高いために靭性は高くなく、加工性も高くないと考えられる。 Patent Document 2 relates to wear resistant steel for medium and normal temperatures used in a region where the temperature is changed from 300 ° C to 400 ° C. Here, toughness and workability are not taken into consideration and their characteristics are not shown, but because Si is very high, toughness is not high and workability is not high.
　特許文献３は、曲げ加工性に優れるＨＢ４００クラスの耐摩耗鋼に関するものであるが、高温環境下での耐摩耗性については全く考慮されていない。 Patent Document 3 relates to HB400 class wear-resistant steel having excellent bending workability, but no consideration is given to wear resistance in a high-temperature environment.
　このように、曲げ加工性の良いＨＢ４００クラス耐摩耗鋼で、かつ３００℃から４００℃になるような高温環境下においても高い耐摩耗性を具備する耐摩耗鋼板としては、これまで適切なものが見当たらない。
　加えて、耐摩耗鋼板は消耗品であるので、経済性も重要な要素であり、高価な合金元素の添加量は極力低いことが望ましい。
特開２００１－４９３８７公報 特開平３－２４３７４３公報 特開２００５－２４０１３５公報 As described above, the HB400 class wear-resistant steel having good bending workability and the wear-resistant steel plate having high wear resistance even in a high temperature environment from 300 ° C. to 400 ° C. are suitable so far. I can't find it.
In addition, since the wear-resistant steel plate is a consumable item, economic efficiency is also an important factor, and it is desirable that the amount of expensive alloy elements added be as low as possible.
JP 2001-49387 A JP-A-3-243743 JP-A-2005-240135
　本発明は、曲げ加工性の良いＨＢ４００クラスの常温硬さであり、かつ３００℃から４００℃になるような高温環境下においても高い耐摩耗性を具備し、さらに経済性にも優れる耐摩耗鋼の提供を目的とする。 The present invention is a wear-resistant steel that is HB400 class room temperature hardness with good bending workability and has high wear resistance even in a high temperature environment of 300 ° C. to 400 ° C., and is also excellent in economy. The purpose is to provide.
　３００℃から４００℃になる高温での耐摩耗性を高めるためには、この温度における硬さを極力高く維持することが重要であると考えられる。一方、ＨＢ４００程度の常温硬さを最も経済的に得る手段は、組織をマルテンサイトにすることである。しかしながら、マルテンサイト組織の鋼板は、温度上昇による硬さの低下が大きい。そこで、ＨＢ４００程度の常温硬さを有するマルテンサイト組織を含有する鋼（マルテンサイト組織鋼）について、高温硬さをできるだけ維持するという観点から、高温耐摩耗性を向上させる検討を行った。 In order to increase the wear resistance at high temperatures from 300 ° C. to 400 ° C., it is considered important to maintain the hardness at this temperature as high as possible. On the other hand, the most economical means of obtaining room temperature hardness of about HB400 is to make the structure martensite. However, a martensitic steel sheet has a large decrease in hardness due to temperature rise. Then, about the steel (martensitic structure steel) containing the martensite structure | tissue which has a normal temperature hardness of about HB400, examination which improves high temperature abrasion resistance from a viewpoint of maintaining high temperature hardness as much as possible was performed.
　本発明が想定しているのは３００℃から４００℃になるような高温環境下であるが、特性評価の代表温度を３５０℃とし、種々の化学組成を有するマルテンサイト組織鋼について、３５０℃における耐摩耗性を調査した。耐摩耗性評価は以下のように行った。ＡＳＴＭＧ９９－０５に準拠したピン・オン・ディスクタイプ摩耗試験装置においてサンプルの温度を制御できるようにして、サンプル温度を３５０℃とした摩耗試験を行い、試験サンプルと標準サンプル（ＳＳ４００）の摩耗量を測定した。そしてＳＳ４００を標準サンプルとして、[ＳＳ４００の摩耗量／試験サンプルの摩耗量]を３５０℃耐摩耗性比として定義し、この３５０℃耐摩耗性比を求めた。この値が大きいほど３５０℃での耐摩耗性が良好であるといえる。 The present invention assumes a high temperature environment of 300 ° C. to 400 ° C., but the typical temperature for characteristic evaluation is set to 350 ° C., and the martensitic steel having various chemical compositions at 350 ° C. The wear resistance was investigated. The abrasion resistance evaluation was performed as follows. In a pin-on-disk type wear test device compliant with ASTM G99-05, the sample temperature is controlled so that the sample temperature is 350 ° C., and the wear amount of the test sample and the standard sample (SS400) is determined. It was measured. Then, using SS400 as a standard sample, [wear amount of SS400 / wear amount of test sample] was defined as a 350 ° C. wear resistance ratio, and this 350 ° C. wear resistance ratio was determined. It can be said that the larger this value, the better the wear resistance at 350 ° C.
　図１は、０．１５％Ｃ－０．５７％Ｓｉ－０．４１％Ｍｎ－１．３７％Ｃｒ－０．０８％Ｍｏ－０．０１２％Ｔｉ－０．００１１％Ｂ－０．００３２％Ｎを基本組成としてＮｂ量を変化させたマルテンサイト組織鋼の、Ｎｂ添加量と３５０℃耐摩耗性比との関係である。Ｎｂ添加量が０～０．０３％までは、３５０℃耐摩耗性比はあまり変化しないが、Ｎｂ添加量が０．０３％を超えると、３５０℃耐摩耗性比は大きく向上する。圧延中に析出するＮｂ炭窒化物は再結晶を抑制して組織を微細化するので、Ｎｂは通常この目的で０．０１～０．０２％が添加される。しかし圧延中に析出したＮｂ炭窒化物は、高温硬さにはあまり寄与しない。一方、鋼板に固溶状態で存在するＮｂは、３００℃から４００℃においては固溶状態のままであるか、ごく微細な炭窒化物として存在し、そのいずれもが高温硬さ向上に寄与すると推される。すなわち、圧延中に析出する量を大きく超える量のＮｂ添加と、適切な圧延および冷却条件の選択によって、鋼板中の固溶Ｎｂを増加させることにより、鋼板が３５０℃に加熱された時点での硬さを高め、その結果３５０℃耐摩耗性を向上することができると考えられる。 FIG. 1 shows 0.15% C-0.57% Si-0.41% Mn-1.37% Cr-0.08% Mo-0.012% Ti-0.0011% B-0.0032% This is the relationship between the Nb addition amount and the 350 ° C. wear resistance ratio of martensitic steel with N as the basic composition and the Nb amount varied. When the Nb addition amount is 0 to 0.03%, the 350 ° C. wear resistance ratio does not change much, but when the Nb addition amount exceeds 0.03%, the 350 ° C. wear resistance ratio is greatly improved. Since Nb carbonitride precipitated during rolling suppresses recrystallization and refines the structure, Nb is usually added in an amount of 0.01 to 0.02% for this purpose. However, Nb carbonitride deposited during rolling does not contribute much to high temperature hardness. On the other hand, Nb existing in a solid solution state in the steel sheet remains in a solid solution state at 300 ° C. to 400 ° C. or exists as a very fine carbonitride, and any of them contributes to an improvement in high temperature hardness. Inferred. That is, when the steel sheet is heated to 350 ° C. by adding Nb in an amount that greatly exceeds the amount precipitated during rolling and by increasing the solid solution Nb in the steel sheet by selecting appropriate rolling and cooling conditions. It is considered that the hardness can be increased, and as a result, the 350 ° C. wear resistance can be improved.
　発明者らは、２５℃でのＨＢが３６０～４４０の範囲内にあるさらに多くのマルテンサイト組織鋼について、合金元素と３５０℃耐摩耗性との関係を詳細に解析した。その結果、３５０℃耐摩耗性比を化学組成から予測する下記の式（１）を導出した。
　ＨＩ＝［Ｃ］＋０．５９［Ｓｉ］－０．５８［Ｍｎ］＋０．２９［Ｃｒ］＋０．３９［Ｍｏ］＋２．１１（［Ｎｂ］－０．０２）－０．７２［Ｔｉ］＋０．５６［Ｖ］　　・・・・（１）
　ここで、［Ｃ］、［Ｓｉ］、［Ｍｎ］、［Ｃｒ］、［Ｍｏ］、［Ｎｂ］、［Ｔｉ］、及び［Ｖ］はそれぞれ、Ｃ、Ｓｉ、Ｍｎ、Ｃｒ、Ｍｏ、Ｎｂ、Ｔｉ、及びＶの含有量（質量％）である。（１）式中、Ｎｂの項において０．０２を減じているのは、圧延中に析出する量を考慮したためである。 The inventors have analyzed in detail the relationship between the alloying elements and the 350 ° C. wear resistance of a larger number of martensitic steels having an HB in the range of 360 to 440 at 25 ° C. As a result, the following formula (1) for predicting the 350 ° C. wear resistance ratio from the chemical composition was derived.
HI = [C] +0.59 [Si] −0.58 [Mn] +0.29 [Cr] +0.39 [Mo] +2.11 ([Nb] −0.02) −0.72 [Ti] +0 56 [V] (1)
Here, [C], [Si], [Mn], [Cr], [Mo], [Nb], [Ti], and [V] are C, Si, Mn, Cr, Mo, Nb, It is content (mass%) of Ti and V. In the formula (1), 0.02 is reduced in the Nb term because the amount precipitated during rolling is taken into consideration.
　図２は、ＨＩと、マルテンサイト組織鋼の３５０℃耐摩耗性比との関係を示す。
　本発明における高温耐摩耗性の目標値は、上記３５０℃耐摩耗性比が３．０以上、すなわち摩耗減量がＳＳ４００の３分の１以下となることと設定する。この目標値を満足するには、図２の関係から、ＨＩを０．７以上とすれば良いことがわかる。さらに、ＨＩを０．８以上とすると、耐摩耗性比は４．０以上となり、さらに良好な耐摩耗性が得られる。 FIG. 2 shows the relationship between HI and the 350 ° C. wear resistance ratio of martensitic steel.
The target value of the high temperature wear resistance in the present invention is set such that the 350 ° C. wear resistance ratio is 3.0 or more, that is, the wear loss is 1/3 or less of SS400. In order to satisfy this target value, it can be seen from the relationship in FIG. 2 that HI should be 0.7 or more. Furthermore, when the HI is 0.8 or more, the wear resistance ratio is 4.0 or more, and a better wear resistance can be obtained.
　（１）式によると、マルテンサイト組織鋼の３５０℃耐摩耗性の向上には、Ｎｂの他、Ｓｉ、Ｃｒ、Ｍｏ、及びＶを多く添加することが有効である。
　このうちＭｏ及びＶは、従来からも高温用鋼に多く用いられている元素であるが、近年価格が非常に高騰しており、経済性の観点からはその添加量は極力小さくすることが望ましい。
　これに対してＳｉ及びＣｒは、比較的安価な元素であるので、３５０℃耐摩耗性の向上に有利な元素であるといえる。また、Ｍｎは、むしろ低減するほうが、３５０℃耐摩耗性には有利である。
　一方、板厚の中心までマルテンサイト組織を得るためには、十分な焼入性を確保することが必要である。耐摩耗鋼の適用板厚は、多くが５０ｍｍまでである。下記Ｃｅｑが０．５０超であれば、５０ｍｍの厚さの鋼板の中心までマルテンサイト組織を得るだけの焼入性を確保できる。
　Ｃｅｑ＝［Ｃ］＋［Ｓｉ］／２４＋［Ｍｎ］／６＋［Ｎｉ］／４０＋［Ｃｒ］／５＋［Ｍｏ］／４＋［Ｖ］／１４
　ここで、［Ｃ］、［Ｓｉ］、［Ｍｎ］、［Ｎｉ］、［Ｃｒ］、［Ｍｏ］、及び［Ｖ］はそれぞれ、Ｃ、Ｓｉ、Ｍｎ、Ｎｉ、Ｃｒ、Ｍｏ、及びＶの含有量（質量％）である。 According to the formula (1), it is effective to add a large amount of Si, Cr, Mo, and V in addition to Nb to improve the 350 ° C. wear resistance of the martensitic steel.
Of these, Mo and V are elements that have been widely used in high temperature steels in the past, but the price has soared in recent years, and it is desirable to reduce the addition amount as much as possible from the viewpoint of economy. .
On the other hand, since Si and Cr are relatively inexpensive elements, it can be said that they are advantageous elements for improving the 350 ° C. wear resistance. Moreover, it is more advantageous for 350 ° C. wear resistance to reduce Mn rather.
On the other hand, in order to obtain a martensite structure up to the center of the plate thickness, it is necessary to ensure sufficient hardenability. The applied plate thickness of wear-resistant steel is often up to 50 mm. If the following Ceq is more than 0.50, it is possible to ensure hardenability sufficient to obtain a martensite structure up to the center of a steel plate having a thickness of 50 mm.
Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14
Here, [C], [Si], [Mn], [Ni], [Cr], [Mo], and [V] contain C, Si, Mn, Ni, Cr, Mo, and V, respectively. Amount (% by mass).
　さらに靭性について、－４０℃でのシャルピー吸収エネルギーを２７Ｊ以上とするためには、Ｓｉ、Ｐ、Ｓ、Ｃｒ、Ｍｏ、Ａｌ、Ｂ、及びＮの含有量の上限を適切に規制する必要がある。 Further, regarding the toughness, in order to make the Charpy absorbed energy at −40 ° C. 27 J or more, it is necessary to appropriately regulate the upper limit of the contents of Si, P, S, Cr, Mo, Al, B, and N .
　本発明は、これらの知見に基づいてなされたものであり、その要旨とするところは下記のとおりである。
（１）本発明の高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板は、質量％で、Ｃ：０．１３％以上、０．１８％以下、Ｓｉ：０．５％以上、１．０％未満、Ｍｎ：０．２％以上、０．８％以下、Ｐ：０．０２０％以下、Ｓ：０．０１０％以下、Ｃｒ：０．５％以上、２．０％以下、Ｍｏ：０．０３％以上、０．３０％以下、Ｎｂ：０．０３％超、０．１０％以下、Ａｌ：０．０１％以上、０．２０％以下、Ｂ：０．０００５％以上、０．００３０％以下、及びＮ：０．０１０％以下を含有し、残部としてＦｅおよび不可避的不純物を含み、成分組成が、下記ＨＩが０．７以上であり、かつＣｅｑが０．５０超であることを満たし、ＨＢ（ブリネル硬さ）が２５℃において３６０以上、４４０以下である。
　ＨＩ＝［Ｃ］＋０．５９［Ｓｉ］－０．５８［Ｍｎ］＋０．２９［Ｃｒ］＋０．３９［Ｍｏ］＋２．１１（［Ｎｂ］－０．０２）－０．７２［Ｔｉ］＋０．５６［Ｖ］
　Ｃｅｑ＝［Ｃ］＋［Ｓｉ］／２４＋［Ｍｎ］／６＋［Ｎｉ］／４０＋［Ｃｒ］／５＋［Ｍｏ］／４＋［Ｖ］／１４
　ここで、［Ｃ］、［Ｓｉ］、［Ｍｎ］、［Ｎｉ］、［Ｃｒ］、［Ｍｏ］、［Ｎｂ］、［Ｔｉ］、及び［Ｖ］はそれぞれ、Ｃ、Ｓｉ、Ｍｎ、Ｎｉ、Ｃｒ、Ｍｏ、Ｎｂ、Ｔｉ、及びＶの含有量（質量％）である。
（２）前記（１）に記載の本発明の高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板では、さらに、質量％で、Ｃｕ：０．０５％以上、１．５％以下、Ｎｉ：０．０５％以上、１．０％以下、Ｔｉ：０．００３％以上、０．０３％以下、及びＶ：０．０１％以上、０．２０％以下のうちの１種または２種以上を含有してもよい。 This invention is made | formed based on these knowledge, The place made into the summary is as follows.
(1) The wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability according to the present invention is in mass%, C: 0.13% or more, 0.18% or less, Si: 0.5% or more, 1.0 %, Mn: 0.2% or more, 0.8% or less, P: 0.020% or less, S: 0.010% or less, Cr: 0.5% or more, 2.0% or less, Mo: 0 0.03% or more, 0.30% or less, Nb: more than 0.03%, 0.10% or less, Al: 0.01% or more, 0.20% or less, B: 0.0005% or more, 0.0030 %, N: 0.010% or less, Fe and unavoidable impurities as the balance, the composition of the following HI is 0.7 or more, and Ceq is more than 0.50 And HB (Brinell hardness) is 360 or more and 440 or less at 25 ° C.
HI = [C] +0.59 [Si] −0.58 [Mn] +0.29 [Cr] +0.39 [Mo] +2.11 ([Nb] −0.02) −0.72 [Ti] +0 .56 [V]
Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14
Here, [C], [Si], [Mn], [Ni], [Cr], [Mo], [Nb], [Ti], and [V] are C, Si, Mn, Ni, It is content (mass%) of Cr, Mo, Nb, Ti, and V.
(2) In the wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability according to the present invention described in (1), Cu: 0.05% or more, 1.5% or less, Ni: 0.05% or more, 1.0% or less, Ti: 0.003% or more, 0.03% or less, and V: 0.01% or more, 0.20% or less You may contain.
（３）本発明の高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板の製造方法は、前記（１）または（２）に記載の組成を有する鋼片または鋳片を１２００℃以上に加熱し、９６０℃以下９００℃以上において累積圧下率が３０％以上６５％以下の熱間圧延を行い、９００℃以上で熱間圧延を終了し、熱間圧延終了後そのまま板厚中心部における冷却速度が５℃／ｓ以上となるように２００℃以下まで加速冷却するか、あるいは熱間圧延終了後２００℃以下まで冷却した後にＡｃ３変態点以上の温度に再加熱し、板厚中心部における冷却速度が５℃／ｓ以上となるように２００℃以下まで加速冷却する。 (3) The method for producing a wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability according to the present invention comprises heating a steel slab or slab having the composition described in (1) or (2) above 1200 ° C. The hot rolling is performed at a cumulative reduction ratio of 30% or more and 65% or less at 960 ° C. or lower and 900 ° C. or higher, and the hot rolling is finished at 900 ° C. or higher. Accelerated cooling to 200 ° C. or lower so that the temperature is 5 ° C./s or higher, or after re-heating to 200 ° C. or lower after completion of hot rolling, reheating to a temperature higher than the Ac3 transformation point, Accelerated cooling to 200 ° C. or lower so as to be 5 ° C./s or higher.
　本発明によれば、曲げ加工性の良いＨＢ４００クラスの常温硬さを有し、かつ３００℃から４００℃になるような高温環境下においても高い耐摩耗性を具備し、さらに経済性にも優れる耐摩耗鋼板を容易に製造できる。 According to the present invention, it has HB400 class room temperature hardness with good bending workability, and has high wear resistance even in a high temperature environment from 300 ° C. to 400 ° C., and is also excellent in economic efficiency. A wear-resistant steel plate can be easily manufactured.
図１は、Ｎｂ添加量と３５０℃における耐摩耗性との関係を示すグラフである。FIG. 1 is a graph showing the relationship between the amount of Nb added and the wear resistance at 350.degree. 図２は、ＨＩと３５０℃における耐摩耗性との関係を示すグラフである。FIG. 2 is a graph showing the relationship between HI and wear resistance at 350 ° C.
　以下、本発明について詳細に説明する。
　まず、本発明の耐摩耗鋼板の鋼成分の限定理由を述べる。
　Ｃは、マルテンサイトの硬さを決定する重要な元素である。本発明において、板厚５０ｍｍまでの板厚中心部における常温ＨＢを３６０以上、４４０以下とするために、Ｃの範囲を０．１３％以上０．１８％以下とする。
　Ｓｉは、３５０℃耐摩耗性を向上させるのに特に有効な元素であり、合金価格も安価である。しかしながら多量のＳｉ添加は靭性を低下させ、加工性も低下させる。こうしたことから、Ｓｉ添加量は０．５０％以上、１．０％未満とする。加工性をより重視する場合には、Ｓｉ添加量は０．８％未満が望ましい。 Hereinafter, the present invention will be described in detail.
First, the reasons for limiting the steel components of the wear-resistant steel sheet of the present invention will be described.
C is an important element that determines the hardness of martensite. In the present invention, the C range is 0.13% or more and 0.18% or less in order to set the room temperature HB at the center of the plate thickness up to 50 mm to 360 to 440.
Si is an element particularly effective for improving the 350 ° C. wear resistance, and the alloy price is also low. However, addition of a large amount of Si reduces toughness and processability. For these reasons, the Si addition amount is set to 0.50% or more and less than 1.0%. In the case where workability is more important, the Si addition amount is desirably less than 0.8%.
　Ｍｎは、ＭｎＳを形成することによって、Ｓの粒界偏析による靭性低下や曲げ加工性低下を回避するために必須であり、０．２％以上を添加する。Ｍｎは焼入性を高めるので、板厚５０ｍｍまでの板厚中心部における常温硬さを確保するためには多く添加するほうがよい。しかし一方でＭｎは高温強度を低下させるので、３５０℃耐摩耗性をむしろ低下させる。このことからＭｎの添加量は、望ましくは０．５％未満の範囲である。焼入性を高める目的でも上限を０．８％とする。したがってＭｎ添加量は、０．２％以上、０．８％以下であり、望ましくは０．２％以上、０．５％未満の範囲である。 Mn is essential in order to avoid a decrease in toughness and bending workability due to segregation of grain boundaries of S by forming MnS, and 0.2% or more is added. Since Mn improves hardenability, it is better to add Mn in order to ensure the normal temperature hardness at the center of the plate thickness up to 50 mm. However, on the other hand, Mn lowers the high-temperature strength, so it rather lowers the 350 ° C. wear resistance. For this reason, the amount of Mn added is desirably less than 0.5%. For the purpose of improving hardenability, the upper limit is made 0.8%. Therefore, the amount of Mn added is 0.2% or more and 0.8% or less, desirably 0.2% or more and less than 0.5%.
　Ｐは、不可避的不純物として、曲げ加工性や靭性を低下させる有害な元素である。したがって、含有量を０．０２０％以下に抑制する。さらに望ましくは、０．０１０％以下とする。Ｐは、曲げ加工性や靭性のためには低いほど望ましいが、０．０００５％未満に低減するためには精錬コストの増大が避けられないため、このような非常に低いレベルに制限する必要はない。 Ｐ P is an inevitable impurity and is a harmful element that reduces bending workability and toughness. Therefore, the content is suppressed to 0.020% or less. More desirably, the content is 0.010% or less. P is preferably as low as possible for bending workability and toughness, but an increase in refining cost is inevitable in order to reduce it to less than 0.0005%. Therefore, it is necessary to limit P to such a very low level. Absent.
　Ｓは、やはり不可避的不純物として、曲げ加工性や靭性を低下させる有害な元素である。したがって、含有量を０．０１０％以下に抑制する。さらに望ましくは、０．００５％以下とする。Ｓは、曲げ加工性や靭性のためには低いほど望ましいが、０．０００５％未満に低減するためには精錬コストの増大が避けられないため、このような非常に低いレベルに制限する必要はない。 S is also an inevitable impurity and is a harmful element that reduces bending workability and toughness. Therefore, the content is suppressed to 0.010% or less. More preferably, it is made 0.005% or less. S is preferably as low as possible for bending workability and toughness, but an increase in refining cost is inevitable in order to reduce it to less than 0.0005%, so it is necessary to limit it to such a very low level. Absent.
　Ｃｒは、焼入性を向上させ、かつ３５０℃耐摩耗性の向上にも有効であることから、少なくとも０．５％以上添加する。板厚５０ｍｍまでの板厚中心部における十分な焼入性を得るためには、添加量は１．０％以上が望ましい。しかしながら、過剰に添加すると靭性を低下させることがあるため、含有量は２．０％以下とする。 Cr is effective in improving hardenability and improving 350 ° C. wear resistance, so is added at least 0.5% or more. In order to obtain sufficient hardenability at the center of the plate thickness up to a plate thickness of 50 mm, the addition amount is desirably 1.0% or more. However, if added excessively, the toughness may be lowered, so the content is made 2.0% or less.
　Ｍｏは、３５０℃耐摩耗性を向上させるとともに、Ｎｂの存在下では微量添加で大きく焼入性を高める効果がある。そのため０．０３％以上の添加を必須とする。しかしながら過剰に添加すると靭性を低下させることがあるので、Ｍｏ添加量は０．３０％を上限とする。またＭｏは近年非常に高価であり、合金コストを抑制する観点からは添加量は０．１０％未満とすることが望ましい。 Mo improves the wear resistance at 350 ° C. and, in the presence of Nb, has the effect of greatly increasing the hardenability by adding a small amount. Therefore, addition of 0.03% or more is essential. However, if excessively added, the toughness may be lowered, so the upper limit of the amount of Mo added is 0.30%. Moreover, Mo is very expensive in recent years, and the addition amount is preferably less than 0.10% from the viewpoint of suppressing alloy costs.
　Ｎｂは、鋼板中に固溶状態で存在することにより、３５０℃耐摩耗性の向上に非常に有効である。十分な固溶Ｎｂを確保するために必要なＮｂ添加量は０．０３％超であり、さらに望ましくは０．０４％以上である。本発明においては、常温でのブリネル硬さＨＢ３６０以上を確保するためにＣを０．１３％以上含むことから、Ｎｂ量が多いとＮｂ（ＣＮ）が加熱時に十分固溶しないことがある。このような未固溶Ｎｂは高温硬さ向上には寄与せず、また靭性低下の原因となることもある。このため、Ｎｂ添加量は０．１０％以下、さらに望ましくは０．０８％以下とする。 Nb is very effective in improving the 350 ° C. wear resistance because it exists in a solid solution state in the steel sheet. The amount of Nb added to ensure sufficient solute Nb is more than 0.03%, and more preferably 0.04% or more. In the present invention, since C is contained in an amount of 0.13% or more in order to ensure a Brinell hardness HB of 360 or more at normal temperature, Nb (CN) may not be sufficiently dissolved at the time of heating if the amount of Nb is large. Such undissolved Nb does not contribute to improving the high temperature hardness and may cause a decrease in toughness. Therefore, the Nb addition amount is set to 0.10% or less, and more desirably 0.08% or less.
　Ａｌは、脱酸元素または介在物形態制御元素として０．０１％以上添加する。また、焼入性向上に必要なフリーＢを確保するためにＮを固定する目的では０．０５％以上を添加する。いずれの場合も過剰な添加は靭性を低下させる場合があるので上限は０．２０％とし、望ましくは０．１０％である。 Al is added in an amount of 0.01% or more as a deoxidation element or inclusion form control element. Moreover, in order to secure the free B necessary for improving the hardenability, 0.05% or more is added for the purpose of fixing N. In either case, excessive addition may reduce toughness, so the upper limit is made 0.20%, preferably 0.10%.
　Ｂは、焼入性を高めるために非常に有効な必須元素である。その効果を発揮するには０．０００５％以上必要であるが、０．００３０％を超えて添加すると溶接性や靭性を低下させることがあるので、Ｂの含有量は０．０００５％以上、０．００３０％以下とする。 B is an essential element that is very effective for improving hardenability. In order to exert the effect, 0.0005% or more is necessary, but if added over 0.0030%, weldability and toughness may be lowered, so the B content is 0.0005% or more, 0 0030% or less.
　Ｎは、過剰に含有されると靱性を低下させるとともに、ＢＮを形成してＢの焼入性向上効果を阻害するので、含有量を０．０１０％以下に抑制する。さらに望ましくは、０．００６％以下である。Ｎは、靭性やＢＮ形成回避のためには低いほど望ましいが、０．００１％未満に低減するためには精錬コストの増大が避けられないため、このような非常に低いレベルに制限する必要はない。 When N is excessively contained, the toughness is reduced, and BN is formed to inhibit the effect of improving the hardenability of B, so the content is suppressed to 0.010% or less. More desirably, it is 0.006% or less. N is preferably as low as possible in order to avoid toughness and BN formation, but in order to reduce it to less than 0.001%, an increase in refining cost is inevitable, so it is necessary to limit to such a very low level. Absent.
　以上は、本発明における鋼の基本成分であるが、さらに本発明では上記成分の他に、Ｃｕ、Ｎｉ、Ｖ、Ｔｉのうち一種または二種以上添加することができる。
　Ｃｕは、靭性を低下させないで硬さを向上させ得る元素であり、その目的のために０．０５％以上添加してもよい。しかしながら、あまり過剰にＣｕを添加するとやはり靭性を低下させることがあるため、添加量は１．５％以下とする。
　Ｎｉは、靭性を向上させるために有効な元素であり、その目的のために０．０５％以上添加しても良い。しかし、Ｎｉは高価な元素であるので、添加は１．０％以下とする。 The above are the basic components of steel in the present invention. In addition, in the present invention, one or more of Cu, Ni, V and Ti can be added in addition to the above components.
Cu is an element that can improve hardness without reducing toughness, and may be added in an amount of 0.05% or more for that purpose. However, if too much Cu is added, the toughness may be lowered, so the addition amount is 1.5% or less.
Ni is an effective element for improving toughness, and 0.05% or more may be added for the purpose. However, since Ni is an expensive element, the addition is made 1.0% or less.
　Ｖは、３５０℃耐摩耗性向上に有効な元素である。この目的のために０．０１％以上を添加してもよい。しかしＶも高価な元素であり、また過剰に添加すると靭性の低下を招く場合があるため、添加する場合でも０．２０％以下とする。
　Ｔｉは、ＮをＴｉＮとして固定することでＢＮを形成させないようにして、焼入性向上に必要なフリーＢを確保するために添加する場合があり、この目的のためには０．００３％以上添加する。しかしながら、Ｔｉ添加によって３５０℃耐摩耗性は低下する傾向がある。したがって、Ｔｉの添加量は０．０３０％以下とする。 V is an element effective for improving the 350 ° C. wear resistance. For this purpose, 0.01% or more may be added. However, V is also an expensive element, and if added excessively, the toughness may be lowered. Therefore, even when added, the content is made 0.20% or less.
Ti may be added so as to prevent formation of BN by fixing N as TiN and to secure free B necessary for improving hardenability. For this purpose, 0.003% or more is added. Added. However, the addition of Ti tends to lower the 350 ° C. wear resistance. Therefore, the amount of Ti added is 0.030% or less.
　以上の成分範囲の限定に加え、上述したように本発明では式（１）のＨＩが０．７以上であり、かつＣｅｑが０．５０超となるように成分組成を限定する。ただし、ＨＩやＣｅｑをあまりに高くすると靭性低下を招くことがあるため、ＨＩは１．２以下、Ｃｅｑは０．７０以下であることが望ましい。 In addition to the above component range limitation, as described above, in the present invention, the component composition is limited so that the HI of formula (1) is 0.7 or more and Ceq is more than 0.50. However, if HI or Ceq is too high, the toughness may be lowered. Therefore, it is desirable that HI is 1.2 or less and Ceq is 0.70 or less.
　次に本発明の耐摩耗鋼板の製造方法について述べる。
　まず、上記の鋼成分組成の鋼片（スラブ）または鋳片を加熱して熱間圧延を行う。
　本発明において熱間圧延に先行する鋼片または鋳片の製造方法は特に限定するものではない。すなわち、高炉、転炉や電炉等による溶製に引き続き、各種の２次精練で目的の成分含有量になるように成分調整を行い、次いで通常の連続鋳造、インゴット法による鋳造の他、薄スラブ鋳造などの方法で鋳造すればよい。原料にはスクラップを使用しても構わない。連続鋳造によって得たスラブの場合には高温鋳片のまま熱間圧延機に直送してもよいし、室温まで冷却後に加熱炉にて再加熱した後に熱間圧延してもよい。鋼片又は鋳片の成分は、前述した本発明の耐摩耗鋼板の成分と同様である。 Next, the manufacturing method of the wear-resistant steel plate of the present invention will be described.
First, hot rolling is performed by heating a steel slab (slab) or slab having the above steel composition.
In the present invention, the method for producing a steel slab or slab prior to hot rolling is not particularly limited. In other words, following smelting with a blast furnace, converter, electric furnace, etc., the components are adjusted so that the desired component content is obtained by various secondary scouring, and then, in addition to normal continuous casting, casting by ingot method, thin slab What is necessary is just to cast by methods, such as casting. Scrap may be used as a raw material. In the case of a slab obtained by continuous casting, it may be directly sent to a hot rolling mill as it is a high-temperature slab, or may be hot-rolled after being reheated in a heating furnace after being cooled to room temperature. The components of the steel slab or slab are the same as the components of the wear-resistant steel plate of the present invention described above.
　鋼片または鋳片の加熱温度は、Ｎｂが十分固溶するように、１２００℃以上とする。ただし、加熱温度をあまりに高くするとオーステナイト組織が粗大化し、そのために熱間圧延後の組織が十分に微細化されないで靭性を低下させることがあるため、鋼片または鋳片の加熱温度は１３５０℃以下が望ましい。
　熱間圧延においては、９６０℃以下９００℃以上において累積圧下率を３０％以上、６５％以下とする。圧延中のＮｂ炭窒化物の析出を、組織の微細化に必要な最小限とするために、この温度及び圧下率の範囲に限定する。
　また、不必要なＮｂ炭窒化物の析出を回避して固溶Ｎｂを多く残すために、熱間圧延は９００℃以上で終了する。また、熱間圧延の終了温度は９６０℃以下とする必要がある。 The heating temperature of the steel slab or slab is set to 1200 ° C. or higher so that Nb is sufficiently dissolved. However, if the heating temperature is too high, the austenite structure becomes coarse, and therefore the structure after hot rolling may not be sufficiently refined and the toughness may be lowered. Therefore, the heating temperature of the steel slab or slab is 1350 ° C. or less. Is desirable.
In hot rolling, the cumulative rolling reduction is set to 30% to 65% at 960 ° C. or lower and 900 ° C. or higher. In order to minimize the precipitation of Nb carbonitride during rolling, it is limited to this temperature and rolling reduction range.
Further, in order to avoid unnecessary Nb carbonitride precipitation and leave a large amount of solid solution Nb, the hot rolling is finished at 900 ° C. or higher. Moreover, the end temperature of hot rolling needs to be 960 degrees C or less.
　熱間圧延後、マルテンサイト組織を得るため、直接焼入れまたは再加熱焼入れにより加速冷却を行う。
　直接焼入れの場合、熱間圧延終了後、直ちに５℃／ｓ以上の冷却速度（板厚中心部における冷却速度）で２００℃以下の温度まで加速冷却を行う。
　再加熱焼入れの場合、熱間圧延終了後、２００℃以下の温度まで一旦冷却し（この際の冷却速度は任意である）、その後、Ａｃ３変態点以上の温度に再加熱して、板厚中心部における冷却速度が５℃／ｓ以上となるように２００℃以下まで加速冷却する。
　直接焼入れの場合の熱間圧延終了後の加速冷却および再加熱焼入れの場合の再加熱後の加速冷却における冷却速度は、板厚が薄くなるほど大きくなる。本願では対象とする板厚は主に４．５ｍｍから５０ｍｍ程度を想定している。板厚４．５ｍｍでの冷却速度は非常に大きくなることがあるが、それによる問題は特になく、冷却速度の上限は規定しない。
　焼戻し熱処理は特に必要ないが、３００℃以下の温度で熱処理しても鋼板の諸特性は本発明を逸脱しない。 In order to obtain a martensite structure after hot rolling, accelerated cooling is performed by direct quenching or reheating quenching.
In the case of direct quenching, accelerated cooling is performed immediately after the hot rolling to a temperature of 200 ° C. or less at a cooling rate of 5 ° C./s or more (cooling rate at the center of the plate thickness).
In the case of reheating and quenching, after completion of hot rolling, it is once cooled to a temperature of 200 ° C. or less (the cooling rate at this time is arbitrary), and then reheated to a temperature not lower than the Ac3 transformation point. Accelerated cooling to 200 ° C. or lower so that the cooling rate at the part is 5 ° C./s or higher.
The cooling rate in accelerated cooling after completion of hot rolling in the case of direct quenching and in accelerated cooling after reheating in the case of reheating quenching increases as the plate thickness decreases. In the present application, the target plate thickness is mainly assumed to be about 4.5 mm to 50 mm. Although the cooling rate at a plate thickness of 4.5 mm may become very large, there is no particular problem, and no upper limit is set for the cooling rate.
Tempering heat treatment is not particularly required, but the properties of the steel sheet do not depart from the present invention even if heat treatment is performed at a temperature of 300 ° C. or lower.
　表１、２に示す組成を有するＡ～ＡＩの鋼を溶製して得られた鋼片を、１２３０℃以上に加熱後、表３，４に示すそれぞれの製造条件で、板厚６～４５ｍｍの鋼板を製造した。（鋼板No.１～１７が本発明例であり、鋼板No.１８～４４が比較例である） Steel strips obtained by melting steels A to AI having the compositions shown in Tables 1 and 2 were heated to 1230 ° C. or higher, and then each of the production conditions shown in Tables 3 and 4 were used to obtain a plate thickness of 6 to 45 mm. The steel plate was manufactured. (Steel plates No. 1 to 17 are examples of the present invention, and steel plates No. 18 to 44 are comparative examples)
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　これらの鋼板について、常温硬さ、３５０℃での耐摩耗性、曲げ加工性、及び靭性を評価した。
　常温硬さについては、ブリネル硬さ試験方法（ＪＩＳ　Ｚ　２２４３）により、２５℃で測定した。常温硬さの目標値はＨＢ３６０以上、ＨＢ４４０以下である。
　耐摩耗性は、上述したようにＡＳＴＭＧ９９－０５に準拠したピン・オン・ディスクタイプ摩耗試験装置においてサンプルの温度を３５０℃とした摩耗試験を行い、ＳＳ４００を標準サンプルとして、耐摩耗性比（ＳＳ４００の摩耗量／試験サンプルの摩耗量）を求めた。耐摩耗性の目標値は、耐摩耗性比３．０以上である。
　曲げ加工性の評価は以下のように行った。ＪＩＳ　Ｚ　２２４８に規定の方法で、試験片ＪＩＳ１号により板厚の４倍の曲げ半径（４ｔ）でのＣ方向　１８０度曲げを行い、曲げ試験後に湾曲部の外側を観察した。湾曲部の外側に裂け傷やその他の欠陥が生じない場合に合格とした。
　靱性の評価は以下のように行った。ＪＩＳ　Ｚ　２２０１　４号シャルピー試験片を板厚中心部から圧延方向に直角に採取し、－４０℃における衝撃試験を行い吸収エネルギー値を測定した。そして３本の試験片の－４０℃における衝撃試験の吸収エネルギー値の平均値を求めた。靭性の目標値は、この平均値が２７Ｊ以上とした。
　得られた結果を表５，６に示す。
　なお、表１～６において、下線を付した数値は、本発明外の成分値や、温度条件および特性が不十分なものを示す。 About these steel plates, normal temperature hardness, the abrasion resistance in 350 degreeC, bending workability, and toughness were evaluated.
About room temperature hardness, it measured at 25 degreeC with the Brinell hardness test method (JISZ2243). The target value of the normal temperature hardness is HB360 or more and HB440 or less.
As described above, the wear resistance ratio (SS400) is determined by performing a wear test at a sample temperature of 350 ° C. in a pin-on-disk type wear test apparatus compliant with ASTM G99-05 as described above. Wear amount / wear amount of the test sample). The target value of wear resistance is an abrasion resistance ratio of 3.0 or more.
Evaluation of bending workability was performed as follows. By the method prescribed in JIS Z 2248, the test piece JIS No. 1 was bent 180 degrees in the C direction at a bending radius (4 t) four times the plate thickness, and the outside of the curved portion was observed after the bending test. The test was accepted when no tears or other defects occurred outside the curved portion.
The toughness was evaluated as follows. A JIS Z 2201 No. 4 Charpy test piece was sampled perpendicularly to the rolling direction from the center of the plate thickness, and subjected to an impact test at -40 ° C. to measure the absorbed energy value. Then, the average value of the absorbed energy values of the impact test at −40 ° C. of the three test pieces was determined. The average value of the toughness target value was set to 27 J or more.
The obtained results are shown in Tables 5 and 6.
In Tables 1 to 6, the underlined numerical values indicate the component values outside the present invention, those having insufficient temperature conditions and characteristics.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　表５の本発明例の鋼板No.１～１７においては、すべて前記の常温硬さ、３５０℃での耐摩耗性、曲げ加工性、及び靭性目標値を満足している。これに対し、本発明により限定された化学組成範囲を逸脱した鋼成分の比較例の鋼板No.１８～４０においては、製造法は本発明法であるにもかかわらず、常温硬さ、３５０℃での耐摩耗性、曲げ加工性、及び靭性のうちの１つ以上が目標値に満たない。また本発明の鋼成分であるが本発明の製造法を逸脱した比較例の鋼板No.４１～４４においても、やはり常温硬さ、３５０℃での耐摩耗性、曲げ加工性、及び靭性のうち１つ以上で不合格となっている。 The steel plates Nos. 1 to 17 of the inventive examples in Table 5 all satisfy the above-mentioned normal temperature hardness, wear resistance at 350 ° C., bending workability, and toughness target values. On the other hand, in steel plates Nos. 18 to 40 of comparative examples of steel components that deviate from the chemical composition range limited by the present invention, although the manufacturing method is the present invention method, the normal temperature hardness is 350 ° C. One or more of the wear resistance, bending workability, and toughness of the steel is less than the target value. Further, in the comparative steel plates Nos. 41 to 44 which are steel components of the present invention but deviate from the production method of the present invention, among the normal temperature hardness, wear resistance at 350 ° C., bending workability, and toughness One or more are rejected.
　本発明によれば、曲げ加工性の良いＨＢ４００クラスの常温硬さを有し、かつ３００℃から４００℃の高温環境下においても高い耐摩耗性を具備し、さらに経済性にも優れる耐摩耗鋼板を容易に製造できる。このため強い衝撃による摩擦熱が生じるブルドーザーのバケットや、高温の物体が衝突する焼結コークスのホッパーなどの高温環境下で高い耐摩耗性が要求される建設機械や産業機械などの部材に好適に利用できる。 According to the present invention, a wear-resistant steel sheet having HB400 class room temperature hardness with good bending workability, high wear resistance even in a high temperature environment of 300 ° C. to 400 ° C., and excellent in economic efficiency. Can be easily manufactured. For this reason, it is suitable for components such as bulldozer buckets that generate frictional heat due to strong impacts and sintered coke hoppers that collide with high-temperature objects, such as construction machinery and industrial machinery that require high wear resistance in high-temperature environments. Available.

Claims (3)

  1. 　質量％で、
    　Ｃ：０．１３％以上、０．１８％以下、
    　Ｓｉ：０．５％以上、１．０％未満、
    　Ｍｎ：０．２％以上、０．８％以下、
    　Ｐ：０．０２０％以下、
    　Ｓ：０．０１０％以下、
    　Ｃｒ：０．５％以上、２．０％以下、
    　Ｍｏ：０．０３％以上、０．３０％以下、
    　Ｎｂ：０．０３％超、０．１０％以下、
    　Ａｌ：０．０１％以上、０．２０％以下、
    　Ｂ：０．０００５％以上、０．００３０％以下、及び
    　Ｎ：０．０１０％以下を含有し、
    　残部としてＦｅおよび不可避的不純物を含み、
    　成分組成が、下記ＨＩが０．７以上であり、かつＣｅｑが０．５０超であることを満たし、
    　ＨＢ（ブリネル硬さ）が２５℃において３６０以上、４４０以下であることを特徴とする高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板。
    　ＨＩ＝［Ｃ］＋０．５９［Ｓｉ］－０．５８［Ｍｎ］＋０．２９［Ｃｒ］＋０．３９［Ｍｏ］＋２．１１（［Ｎｂ］－０．０２）－０．７２［Ｔｉ］＋０．５６［Ｖ］
    　Ｃｅｑ＝［Ｃ］＋［Ｓｉ］／２４＋［Ｍｎ］／６＋［Ｎｉ］／４０＋［Ｃｒ］／５＋［Ｍｏ］／４＋［Ｖ］／１４
    　ここで、［Ｃ］、［Ｓｉ］、［Ｍｎ］、［Ｎｉ］、［Ｃｒ］、［Ｍｏ］、［Ｎｂ］、［Ｔｉ］、及び［Ｖ］はそれぞれ、Ｃ、Ｓｉ、Ｍｎ、Ｎｉ、Ｃｒ、Ｍｏ、Ｎｂ、Ｔｉ、及びＶの含有量（質量％）である。     % By mass
    C: 0.13% or more, 0.18% or less,
    Si: 0.5% or more and less than 1.0%,
    Mn: 0.2% or more, 0.8% or less,
    P: 0.020% or less,
    S: 0.010% or less,
    Cr: 0.5% or more, 2.0% or less,
    Mo: 0.03% or more, 0.30% or less,
    Nb: more than 0.03%, 0.10% or less,
    Al: 0.01% or more, 0.20% or less,
    B: 0.0005% or more, 0.0030% or less, and N: 0.010% or less,
    Containing Fe and inevitable impurities as the balance,
    The component composition satisfies that the following HI is 0.7 or more and Ceq is more than 0.50,
    A wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability, characterized in that HB (Brinell hardness) is 360 or more and 440 or less at 25 ° C.
    HI = [C] +0.59 [Si] −0.58 [Mn] +0.29 [Cr] +0.39 [Mo] +2.11 ([Nb] −0.02) −0.72 [Ti] +0 .56 [V]
    Ceq = [C] + [Si] / 24 + [Mn] / 6 + [Ni] / 40 + [Cr] / 5 + [Mo] / 4 + [V] / 14
    Here, [C], [Si], [Mn], [Ni], [Cr], [Mo], [Nb], [Ti], and [V] are C, Si, Mn, Ni, It is content (mass%) of Cr, Mo, Nb, Ti, and V.
  2. 　さらに、質量％で、Ｃｕ：０．０５％以上、１．５％以下、Ｎｉ：０．０５％以上、１．０％以下、Ｔｉ：０．００３％以上、０．０３％以下、及びＶ：０．０１％以上、０．２０％以下のうちの１種または２種以上を含有することを特徴とする請求項１に記載の高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板。 Further, by mass, Cu: 0.05% or more, 1.5% or less, Ni: 0.05% or more, 1.0% or less, Ti: 0.003% or more, 0.03% or less, and V The wear-resistant steel sheet having excellent high-temperature wear resistance and bending workability according to claim 1, characterized by containing one or more of 0.01% or more and 0.20% or less.
  3. 　請求項１または請求項２に記載の組成を有する鋼片または鋳片を１２００℃以上に加熱し、９６０℃以下９００℃以上において累積圧下率が３０％以上６５％以下の熱間圧延を行い、９００℃以上で熱間圧延を終了し、
    　熱間圧延終了後そのまま板厚中心部における冷却速度が５℃／ｓ以上となるように２００℃以下まで加速冷却するか、あるいは熱間圧延終了後２００℃以下まで冷却した後にＡｃ３変態点以上の温度に再加熱し、板厚中心部における冷却速度が５℃／ｓ以上となるように２００℃以下まで加速冷却することを特徴とする高温耐摩耗性および曲げ加工性に優れる耐摩耗鋼板の製造方法。
          A steel slab or slab having the composition according to claim 1 or 2 is heated to 1200 ° C or higher, and hot rolling is performed at a cumulative reduction of 30% to 65% at 960 ° C or lower and 900 ° C or higher, Finish hot rolling at 900 ° C or higher,
    After completion of hot rolling, it is accelerated to 200 ° C. or less so that the cooling rate at the center of the sheet thickness is 5 ° C./s or more, or after cooling to 200 ° C. or less after completion of hot rolling, the Ac3 transformation point or more. Reheating to temperature, accelerated cooling to 200 ° C. or lower so that the cooling rate at the center of the plate thickness is 5 ° C./s or higher, producing a wear-resistant steel plate with excellent high temperature wear resistance and bending workability Method.
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BRPI0901014A2 (en) 2015-06-23
EP2180076A1 (en) 2010-04-28
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CN101680071A (en) 2010-03-24
KR20090102791A (en) 2009-09-30
US20100139820A1 (en) 2010-06-10
AU2009203476B2 (en) 2010-10-07
KR101033711B1 (en) 2011-05-09
TWI341332B (en) 2011-05-01
AU2009203476A1 (en) 2009-07-16
EP2180076B1 (en) 2016-03-30
JP4590012B2 (en) 2010-12-01
CN101680071B (en) 2012-12-26
EP2180076A4 (en) 2013-10-23

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