WO2013161026A1 - パーライトレール、パーライトレールのフラッシュバット溶接方法、およびパーライトレールの製造方法 - Google Patents
パーライトレール、パーライトレールのフラッシュバット溶接方法、およびパーライトレールの製造方法 Download PDFInfo
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- WO2013161026A1 WO2013161026A1 PCT/JP2012/061147 JP2012061147W WO2013161026A1 WO 2013161026 A1 WO2013161026 A1 WO 2013161026A1 JP 2012061147 W JP2012061147 W JP 2012061147W WO 2013161026 A1 WO2013161026 A1 WO 2013161026A1
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- rail
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- pearlite
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- temperature
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- 229910001562 pearlite Inorganic materials 0.000 title claims abstract description 75
- 238000003466 welding Methods 0.000 title claims abstract description 60
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 title claims abstract description 22
- 239000012535 impurity Substances 0.000 claims abstract description 10
- 229910052804 chromium Inorganic materials 0.000 claims abstract description 7
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 5
- 238000001816 cooling Methods 0.000 claims description 68
- 229910001567 cementite Inorganic materials 0.000 claims description 51
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 claims description 51
- 238000005096 rolling process Methods 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 23
- 238000005098 hot rolling Methods 0.000 claims description 15
- 239000000126 substance Substances 0.000 claims description 11
- 230000009467 reduction Effects 0.000 claims description 10
- 229910052750 molybdenum Inorganic materials 0.000 claims description 5
- 229910052759 nickel Inorganic materials 0.000 claims description 5
- 229910052758 niobium Inorganic materials 0.000 claims description 5
- 229910052720 vanadium Inorganic materials 0.000 claims description 5
- 239000010451 perlite Substances 0.000 claims description 4
- 235000019362 perlite Nutrition 0.000 claims description 4
- 238000003303 reheating Methods 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 229910000831 Steel Inorganic materials 0.000 description 17
- 239000010959 steel Substances 0.000 description 17
- 230000007423 decrease Effects 0.000 description 12
- 229910001566 austenite Inorganic materials 0.000 description 11
- 230000000694 effects Effects 0.000 description 11
- 238000010586 diagram Methods 0.000 description 10
- 229910000734 martensite Inorganic materials 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 230000009466 transformation Effects 0.000 description 7
- 229910000859 α-Fe Inorganic materials 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 229910017112 Fe—C Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- 230000006872 improvement Effects 0.000 description 4
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- 238000004364 calculation method Methods 0.000 description 2
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- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000004781 supercooling Methods 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 238000007545 Vickers hardness test Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
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- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
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Images
Classifications
-
- 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
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/002—Resistance welding; Severing by resistance heating specially adapted for particular articles or work
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K11/00—Resistance welding; Severing by resistance heating
- B23K11/04—Flash butt welding
-
- 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
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/004—Heat treatment of ferrous alloys containing Cr and Ni
-
- 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
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- 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
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- 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
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- 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
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium 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
- C22C38/26—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
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
- C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
-
- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
- E01B5/00—Rails; Guard rails; Distance-keeping means for them
- E01B5/02—Rails
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Definitions
- the present invention relates to a pearlite rail having high hardness and high toughness with little softening of the weld heat affected zone, a flash butt welding method of the pearlite rail, and a method of manufacturing the pearlite rail.
- the loading weight is heavier than that of passenger cars, so the load applied to the axle of the freight car is high, and the contact environment between the rails and wheels is very severe.
- the rail used in such a contact environment is required to have wear resistance, and steel having a pearlite structure is conventionally used.
- Patent Documents 1 to 4 describe a hypereutectoid rail having an increased amount of cementite and a method for producing the same.
- Patent Documents 5 to 7 describe techniques for increasing the hardness by reducing the lamellar spacing of the pearlite structure in the eutectoid carbon level steel.
- the rails are cut and shipped at predetermined lengths, and the rail joints are made continuous by factory welding such as flash butt welding and gas pressure welding at the customer site, and on-site welding such as Encro welding and thermite welding. Long rail. In this way, efforts are made to reduce vibration and noise generated at rail joints. Therefore, the hardness, fatigue characteristics, and ductility of the rail weld are also important in considering the failure of the rail-to-rail weld (rail weld), as well as the hardness, fatigue characteristics, and ductility of the rail base material. Become an element.
- Patent Document 10 A technique focusing on the hardness of such a rail weld is proposed in Patent Document 10.
- the flash butt welding method and welding conditions are used in order to suppress the softening of the part affected by the welding heat of the rail (welding heat affected part) and reduce the uneven wear of the rail. Is optimized.
- Patent Document 10 is not a technique for examining a rail base material suitable for increasing the hardness of a rail welded part in regard to the welding technique.
- the present invention has been made in order to solve the above-described problems, and has a high hardness and high ductility tough pearlite rail, a pearlite rail flash butt welding method, and a pearlite rail. It aims at providing the manufacturing method of.
- the inventor of the present invention diligently studied the hardness of the weld heat-affected zone, particularly the softened portion of the weld heat-affected zone and the width of the softened zone, as described above.
- the pearlite rail according to the present invention is C: 0.70 to 1.0%, Si: 0.1 to 1.5%, Mn: 0.01 to 1.5%, P: 0.001 to 0.035%, S: 0.0005 to 0.030%, Cr: 0.1 to 2.0%, the balance being Fe and inevitable And a ⁇ + ⁇ temperature range of 100 ° C. or lower.
- the pearlite rail according to the present invention is the above-described invention, further Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Mo: 0.01 to 0.5%, V: One or more of 0.001 to 0.15% and Nb: 0.001 to 0.030% are contained, the balance is Fe and inevitable impurities, and the ⁇ + ⁇ temperature range is 100 ° C. or less. It is characterized by that.
- the pearlite rail according to the present invention is, in mass percent, C: 0.70 to 1.0%, Si: 0.1 to 1.5%, Mn: 0.01 to 1.5%, P: 0 0.001 to 0.035%, S: 0.0005 to 0.030%, Cr: 0.1 to 2.0%, with the balance being Fe and inevitable impurities, ⁇ + ⁇ temperature range of 100 ° C
- the width of the softened part having a Vickers hardness of HV300 or less in the welding heat-affected zone formed when flash butt welding in which the residence time in the ⁇ + ⁇ temperature range is 200 s or less is 15 mm or less,
- the hardness is HV270 or more.
- the pearlite rail according to the present invention is the above-described invention, Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Mo: 0.01 to 0.5%, V: 0 Further, one or more of 0.001 to 0.15%, Nb: 0.001 to 0.030% are further contained, the balance is Fe and inevitable impurities, and the ⁇ + ⁇ temperature range is 100 ° C. or less.
- the width of the softened portion having a Vickers hardness of HV300 or less in the weld heat-affected zone when welding is 15 mm or less, and the hardness of the softest portion is HV270 or more.
- the cementite number ratio in which the ratio of the short side to the long side (aspect ratio) of the cementite at the softest portion of the weld heat affected zone is 5 or less is the total amount of cementite. It is characterized by being 50% or less.
- the flash butt welding method of the pearlite rail according to the present invention is such that when the pearlite rail is flash butt welded, in the upset and the subsequent cooling, the residence time in the ⁇ + ⁇ temperature range is 200 s or less, and the weld heat affected zone is softened.
- the width is 15 mm or less, and the hardness of the softest part is HV270 or more.
- the manufacturing method of the pearlite rail which concerns on this invention is a manufacturing method of the pearlite rail which manufactures a rail by hot rolling using the rail raw material which has the chemical component of the said invention, Comprising: After hot rolling, 720 degreeC or more Accelerated cooling is started at a temperature of 500 ° C or less, accelerated cooling is performed at a cooling rate of 1 ° C / s to 10 ° C / s to 500 ° C or less, and then cooled, and the rail surface is reheated to 400 ° C or more. To do.
- the manufacturing method of the pearlite rail which concerns on this invention is a manufacturing method of the pearlite rail which manufactures a rail by hot rolling using the rail raw material which has the chemical component of the said invention, Comprising: It is 1000 degrees C or less, and area reduction rate 20 %, And hot rolling with a finishing temperature of 800 ° C. or higher is started, then accelerated cooling is started from 720 ° C. or higher, and accelerated cooling is performed at a cooling rate of 1 ° C./s to 10 ° C./s to 500 ° C. or lower. Then, it is allowed to cool, and the rail surface is reheated to 400 ° C. or higher.
- the method for producing a pearlite rail according to the present invention is characterized in that, in the above invention, the surface hardness of the rail top is HV370 or more, the tensile strength is 1300 MPa or more, and the 0.2% proof stress is 827 MPa or more.
- the manufacturing method of the pearlite rail which concerns on this invention sets the hardness of the surface of a rail top to HV370 or more, tensile strength is 1300 MPa or more, 0.2% proof stress is 827 MPa or more, and elongation is 10% or more in the said invention. It is characterized by that.
- the present invention it is possible to provide a high-hardness and high-toughness pearlite rail, a flash butt welding method of pearlite rail, and a pearlite rail manufacturing method with less softening of the heat affected zone.
- FIG. 1 is a diagram showing an Fe—C phase diagram of Fe—C—0.5Si—0.7Mn—0.2Cr steel.
- FIG. 2 is a diagram showing the relationship between the maximum temperature achieved as a result of the thermal cycle test and the hardness in one embodiment of the present invention.
- FIG. 3 is a diagram showing the relationship between the ⁇ + ⁇ temperature range as a result of the thermal cycle test in the present embodiment and the temperature range in which the hardness is HV300 or less.
- FIG. 4 is a diagram showing the relationship between the cementite spheroidization rate and the maximum temperature achieved in the present embodiment.
- FIG. 5 is a diagram showing the relationship between the residence time in the ⁇ + ⁇ temperature range and the hardness of the most softened portion of the welding heat affected zone in the present embodiment.
- FIG. 6 is a diagram showing the relationship between the residence time in the ⁇ + ⁇ temperature range in this embodiment and the softening width of the weld heat affected zone where the hardness is HV300 or less.
- FIG. 1 shows an Fe—C phase diagram of Fe—C—0.5Si—0.7Mn—0.2Cr steel (Source: B. Jansson, M. Schalin, M. Selleby and B. Sundman: Computer Software in Chemical and Extractive Metallurgy, ed.By C.W.Bale et al., (The Metall. Soc. CIM, Quebec, 1993), 57-71.
- the structure change by the temperature rise accompanying welding is shown below about the rail base material of 0.8% C which is exhibiting the pearlite structure.
- the pearlite structure is generally maintained at a temperature of approximately 720 ° C. or lower at which ferrite ( ⁇ ) changes to austenite ( ⁇ ).
- ferrite ( ⁇ ) changes to austenite ( ⁇ ).
- the temperature exceeds 720 ° C., the ferrite ( ⁇ ) is transformed into austenite ( ⁇ ), and a temperature range in which three phases of ferrite ( ⁇ ), cementite ( ⁇ ), and austenite ( ⁇ ) coexist is obtained.
- (3) When the temperature further rises to 730 ° C. or higher, two phases of cementite ( ⁇ ) and austenite ( ⁇ ) are obtained.
- the shape of rod-shaped cementite ( ⁇ ) changes in a direction that reduces the interfacial energy as the temperature rises during welding, so in the part heated to the two-phase temperature range of austenite ( ⁇ ) and cementite ( ⁇ ), cementite ( ⁇ ) is divided and spheroidized. (4) When the temperature is further increased, an austenite ( ⁇ ) single phase is obtained. (5) It melts at higher temperatures.
- the temperature of the joint rises to the melting temperature or higher (that is, (5)), but as the distance from the joint increases, the temperature rise due to welding decreases and the maximum temperature of each part is reached. Accordingly, the microstructure changes from (4) ⁇ (3) ⁇ (2) ⁇ (1) where the pearlite structure is maintained.
- the rail After the temperature of the rail weld reaches the maximum temperature, the rail is cooled by blast cooling from the viewpoint of suppressing softening of the rail weld.
- the cooling rate at that time is 1 to 3 ° C./s, and cooling is performed at 1 ° C./s, which corresponds to the lower limit of the cooling rate after welding, and the maximum achieved temperature and hardness (Vickers hardness) and cementite ( ⁇ )
- FIG. 2 the rail was most softened when it was heated until the maximum temperature reached the temperature ( ⁇ + ⁇ temperature) in which the above-mentioned two phases of cementite ( ⁇ ) and austenite ( ⁇ ) were reached ( ⁇ ).
- the heated rail structure was observed by SEM ((a): base material not subjected to heat treatment, (b): structure heated to a maximum reached temperature of 700 ° C., (c): heated to a maximum reached temperature of 750 ° C. Structure (d): structure heated to a maximum reached temperature of 800 ° C.) and cementite phase in the pearlite structure (layered structure of ferrite and cementite) is markedly spheroidized in the 750 ° C. heated structure (c). I understood. That is, the softening in FIG. 2 is a reduction in hardness because undissolved cementite ( ⁇ ) changes to a stable spherical shape and the spherical cementite ( ⁇ ) remains after cooling. is there.
- the pearlite structure of the base material was basically maintained even when the maximum temperature reached was less than the ⁇ + ⁇ temperature, the decrease in hardness was small. That is, in the Fe—C phase diagram shown in FIG. 1, the portion heated to the ⁇ + ⁇ temperature range is the portion where cementite ( ⁇ ) is spheroidized and softened most.
- FIG. 3 is a diagram in which the results are arranged with the horizontal axis as the ⁇ + ⁇ temperature range and the vertical axis as the temperature range in which the Vickers hardness is HV300 or less (in a thermal cycle test assuming a thermal history during welding).
- the ⁇ + ⁇ temperature range exceeds 100 ° C.
- the temperature range in which cementite ( ⁇ ) spheroidizes increases, so the temperature range in which the weld heat affected zone softens increases.
- the softening of the weld heat affected zone was analyzed from the spheroidizing behavior of cementite. Quantification was performed by defining the spheroidization rate of cementite as follows. The microstructure of the weld heat-affected zone was observed with a scanning electron microscope (SEM) at a magnification of 10,000 times or more, and the number of relatively spherical cementites having an aspect ratio (aspect ratio) of 5 or less (A ) was counted, and the ratio to the total number of cementite (B) was determined by the following formula (C), which was defined as the cementite spheroidization rate.
- SEM scanning electron microscope
- Spheroidization ratio number of cementites with an aspect ratio of 5 or less (A) / total number of cementites (B) x 100 (C)
- the number of cementite to be used is 100 or more or 100 ⁇ m 2 or more in the measurement visual field.
- FIG. 4 is a graph showing the relationship between the cementite spheroidization rate and the maximum temperature reached. As shown in FIG. 4, it can be seen that the softened region seen in FIG. 2 corresponds to a region where the spheroidization rate of cementite exceeds 50%. That is, according to the detailed examination results so far, it has been clarified that when the ⁇ + ⁇ temperature range exceeds 100 ° C., cementite spheroidization is remarkably promoted and the hardness of the weld heat affected zone is greatly reduced.
- C 0.70 to 1.0%
- C is an important element for forming cementite for pearlite rails, increasing hardness and strength, and improving wear resistance.
- the lower limit of the C amount is set to 0.7%.
- an increase in the amount of C means an increase in the amount of cementite, and an increase in hardness and strength can be expected, but the ductility decreases on the contrary.
- an increase in the amount of C expands the ⁇ + ⁇ temperature range and promotes softening of the weld heat affected zone. Considering these adverse effects, the upper limit of the C amount is set to 1.0%.
- a preferred range for the amount of C is 0.70 to 0.95%.
- Si 0.1 to 1.5% Si is added to the rail base material for strengthening the deoxidized material and the pearlite structure, but these effects are small when the amount is less than 0.1%. On the other hand, addition of Si in an amount exceeding 1.5% tends to cause poor bonding during welding, promotes surface decarburization, and easily generates martensite in the rail base material. 1.5%. Preferably, the Si amount is in the range of 0.2 to 1.3%.
- Mn 0.01 to 1.5%
- Mn has the effect of lowering the pearlite transformation temperature and finer the pearlite lamellar spacing (lamellar spacing of the pearlite structure), so it is an effective element for maintaining high hardness inside the rail, but less than 0.01% The amount is less effective.
- the addition of Mn in an amount exceeding 1.5% lowers the equilibrium transformation temperature (TE) of pearlite and easily causes martensitic transformation. Therefore, the upper limit of the amount of Mn is set to 1.5%.
- the amount of Mn is in the range of 0.3 to 1.3%.
- the upper limit of the P amount is 0.035% or less.
- the upper limit of the P amount is 0.025%.
- the lower limit of the P amount is set to 0.001% because special refining or the like causes an increase in melting costs.
- S forms coarse MnS that extends in the rolling direction and reduces ductility and delayed fracture characteristics.
- 0.030% is set as the upper limit of the amount of S in consideration of these.
- the lower limit of the amount of S is set to 0.0005% because the cost increase at the time of melting such as an increase in the melting time is significant.
- the S content is in the range of 0.001 to 0.020%.
- Cr 0.1 to 2.0% Cr increases the equilibrium transformation temperature (TE), contributes to the refinement of the pearlite lamellar spacing, and increases the hardness and strength. Therefore, it is necessary to add Cr in an amount of 0.1% or more. On the other hand, the addition of Cr in an amount exceeding 2.0% increases the occurrence of weld defects (decreases weldability), increases the hardenability and promotes the formation of martensite. 0.0%. More preferably, the Cr content is in the range of 0.2% to 1.5%.
- the chemical composition further includes Cu: 0.01 to 1.0%, Ni: 0.01 to 0.5%, Mo: 0.01 to 0.5%, V: 0.001 to 0 One or more of 15% and Nb: 0.001 to 0.030% can be added.
- Cu 0.01 to 1.0%
- Cu is an element that can achieve higher hardness by solid solution strengthening. However, in order to expect this effect, it is necessary to add Cu in an amount of 0.01% or more. On the other hand, addition of Cu in an amount exceeding 1.0% tends to cause surface cracks during continuous casting or rolling, so the upper limit of Cu content is 1.0%.
- the amount of Cu is more preferably in the range of 0.05 to 0.6%.
- Ni 0.01 to 0.5%
- Ni is an effective element that improves toughness and ductility. Moreover, since it is an effective element which suppresses a Cu crack by adding together with Cu, it is desirable to add Ni also when adding Cu. However, since these effects are not observed when the Ni content is less than 0.01%, the lower limit of the Ni content is set to 0.01%. On the other hand, the addition of Ni in an amount exceeding 0.5% increases the hardenability and promotes the formation of martensite, so the upper limit of the Ni amount is set to 0.5%. More preferably, the Ni content is in the range of 0.05 to 0.3%.
- Mo 0.01 to 0.5% Mo is an element effective for increasing the strength. However, since the effect is small when the amount is less than 0.01%, the lower limit of the amount of Mo is set to 0.01%. On the other hand, the addition of Mo in an amount exceeding 0.5% produces martensite as a result of improving hardenability, and thus extremely reduces toughness and ductility. Therefore, the upper limit was made 0.5%. Preferably, the Mo amount is in the range of 0.05 to 0.3%.
- V 0.001 to 0.15%
- V is an element that forms VC or VN and precipitates finely in ferrite, and is effective in increasing the strength through precipitation strengthening of ferrite. It also functions as a hydrogen trap site and can be expected to suppress delayed fracture. For this purpose, it is necessary to add V in an amount of 0.001% or more. On the other hand, the addition of V in an amount exceeding 0.1% saturates these effects and significantly increases the alloy cost, so the upper limit of the V amount was set to 0.15%. As a preferred range, the V amount is in the range of 0.005 to 0.12%.
- Nb 0.001 to 0.030%
- Nb is an element effective in increasing the toughness by increasing the non-recrystallization temperature of austenite and effective in reducing the size of pearlite colonies and blocks by introducing processing strain into the austenite during rolling.
- Nb in an amount of 0.001% or more.
- addition of Nb in an amount exceeding 0.030% causes Nb carbonitride to crystallize during the solidification process and lowers the cleanliness, so the upper limit of Nb content was set to 0.030%.
- the Nb amount is in the range of 0.003 to 0.025%.
- the balance other than the chemical components described above is Fe and inevitable impurities.
- the P amount and the S amount have been described above.
- the N content can be up to 0.015%
- the O content can be up to 0.004%
- the H content can be up to 0.0003%.
- ⁇ + ⁇ temperature range is 100 ° C. or less: If the ⁇ + ⁇ temperature range exceeds 100 ° C, spheroidization of cementite is promoted during flash butt welding of the rail, the hardness of the softest part of the weld heat affected zone decreases to HV370 or less, and the softening width of the part where HV300 or less Will also expand. Therefore, the ⁇ + ⁇ temperature range needs to be 100 ° C. or less.
- the lower limit of the ⁇ + ⁇ temperature range is not particularly specified. However, if the ⁇ + ⁇ temperature range is less than 10 ° C, the hardness and strength of the rail base material are lowered.
- the lower limit of the ⁇ + ⁇ temperature range is desirably 10 ° C.
- a preferable range of the ⁇ + ⁇ temperature range is 10 to 90 ° C.
- For the ⁇ + ⁇ temperature range create a Fe-C equilibrium diagram corresponding to the component system using a calculation tool such as “Thermo-calc”, which is a calculation tool for transition to thermodynamics, and obtain the ⁇ + ⁇ temperature and ⁇ + ⁇ temperature ranges. I will do it. If necessary, the spheroidization state of cementite may be examined by conducting a heat cycle test.
- Hardness HV370 or more and HV300 or less of the softest part of the weld heat affected zone Softening width of the weld heat affected zone 15 mm or less:
- the rail top is worn and rolled fatigue due to rolling contact with the wheels.
- wear and rolling fatigue occur in both. If the range of the softened or softened portion of the weld heat affected zone is large in this rail welded portion, the softened portion is quickly worn against the rail base material (uneven wear).
- the rail of the rail welded portion Uneven wear with the base material is reduced, and noise and vibration are reduced. From this, the hardness of the most softened portion of the welded portion was set to HV370 or more, and the softening width of the weld heat affected zone where the hardness was HV300 or less was set to 15 mm or less.
- the ratio of the cementite whose short side to long side ratio (aspect ratio) is 5 or less is 50% or less with respect to the total amount of cementite:
- the portion of cementite that is heated and held in the ⁇ + ⁇ temperature range at the time of welding is spheroidized, and the softening and softening width increase. Therefore, the ratio of the number of cementite whose ratio of short side to long side (aspect ratio) of cementite is 5 or less. It is necessary to make it 50% or less with respect to the total amount of cementite.
- FIG. 5 is a diagram showing the relationship between the residence time in the ⁇ + ⁇ temperature range and the hardness of the most softened portion of the weld heat affected zone.
- FIG. 6 is a diagram showing the relationship between the residence time in the ⁇ + ⁇ temperature range and the softening width of the weld heat affected zone where the Vickers hardness is HV300 or less.
- the residence time in the ⁇ + ⁇ temperature range exceeds 200 s
- the hardness of the most softened portion of the weld heat affected zone softens to HV270 or less
- the softening width to become HV300 or less is also 15 mm. It turns out that the softening of the heat affected zone of welding becomes remarkable.
- the rail After hot rolling, the rail starts accelerated cooling at a temperature of 720 ° C. or higher, and is accelerated to a temperature of 500 ° C. or lower at a cooling rate of 1 ° C./s to 10 ° C./s. It is necessary to reheat to 400 ° C or higher.
- Cooling rate 1 ° C / s to 10 ° C / s:
- the accelerated cooling needs to be performed at a cooling rate of 1 ° C./s to 10 ° C./s.
- the cooling rate is less than 1 ° C./s, the pearlite transformation temperature increases and the degree of supercooling ( ⁇ T) decreases, so that the pearlite lamellar spacing increases, and the hardness and strength decrease.
- the cooling rate exceeds 10 ° C./s, martensite is likely to be generated on the rail surface, and the toughness and fatigue characteristics are lowered. Therefore, the cooling rate needs to be in the range of 1 to 10 ° C./s.
- a preferable range of the cooling rate is 1.5 ° C./s to 7 ° C./s.
- Cooling stop temperature 500 ° C or less The cooling stop temperature for accelerated cooling must be 500 ° C. or lower. When the cooling stop temperature is higher than 500 ° C., the accelerated cooling is stopped in the middle of the pearlite transformation, and particularly the hardness inside the rail is greatly reduced. Therefore, the cooling stop temperature needs to be 500 ° C. or lower. Although the lower limit of the cooling stop temperature is not particularly defined, accelerated cooling to 250 ° C. or lower should be avoided in order to prevent martensitic transformation. For this reason, the range of the cooling stop temperature is desirably 500 ° C. to 250 ° C.
- the rail surface After accelerating cooling to 500 ° C. or lower, it is allowed to cool and the rail surface is reheated to 400 ° C. or higher: After accelerated cooling to 500 ° C. or lower, the rail surface is allowed to cool and the rail surface needs to be reheated to 400 ° C. or higher.
- the recuperation temperature of the rail surface needs to be 400 ° C. or higher.
- Rolling temperature of 1000 ° C. or less and area reduction of 20% or more In general, rail rolling is hot-rolled by a breakdown mill, a rough mill, and a finish mill, and the area reduction rate is 20% or less at 1000 ° C. or less in the rolling process of the rough mill and the finish mill.
- the pearlite block and colony size are refined, and further improvement in ductility can be expected.
- Rolling with a reduction in area of 20% or more at 1000 ° C or higher, or rolling with a reduction in area of less than 20% even at 1000 ° C or less the pearlite block and colony size are not sufficiently refined, and the toughness of the rail base material is poor. It is not enough for improvement.
- Rolling finishing temperature of 800 ° C or higher The rolling finishing temperature needs to be 800 ° C. or higher.
- the rolling finishing temperature is less than 800 ° C., the cooling start temperature during the subsequent accelerated cooling is lowered, so that the formation of a pearlite structure having fine lamellarness becomes insufficient, resulting in a decrease in hardness and strength. Therefore, the rolling finishing temperature needs to be 800 ° C. or higher. Desirably, it is 850 degreeC or more.
- a rail base material excellent in ductility can be obtained while maintaining high hardness and high strength by following the cooling conditions described above.
- Rail surface hardness HV370 or more At the rail top, delamination damage due to the generation and propagation of surface cracks occurs due to wear due to contact with the wheels and rolling fatigue. In particular, when the hardness of the rail surface is low, the wear resistance is lowered. In railways mainly mine railways and freight railways, the amount of wear increases due to the high stress on the rails, and the rail life is reduced. When the surface hardness of the rail is less than HV370, the wear of the rail is remarkable, so the hardness of the surface of the rail requires HV370 or more. Preferably, the hardness of the surface of the rail is HV380 or more.
- Tensile strength 1300 MPa or more Basically, the tensile strength at a depth of 0.5 inches is equivalent to the hardness, and in order to improve the wear resistance of the rail, a tensile strength of 1300 MPa or more is required.
- 0.2% proof stress 827 MPa or more The 0.2% proof stress at a depth of 0.5 inches requires 827 MPa or more.
- the 0.2% proof stress of the rail should be high, and 827 MPa or more is required.
- the 0.2% proof stress is high with respect to rolling fatigue. If the proof stress is 827 MPa or more, it can be expected that the rail for heavy cargo railway will exhibit sufficient fatigue characteristics.
- Elongation 10% or more Due to the generation and growth of fatigue cracks, there is a concern that the rail will eventually break, resulting in a major accident. In order to suppress the breakage, it is desirable that the ductility (elongation) is high. However, when improving durability with a rail having a pearlite structure, it is necessary to achieve both high hardness and high toughness. In the case of high-hardness pearlite rails, which are important for wear resistance and laid on railways such as heavy freight railways, if the elongation is 10% or more, a serious accident can be suppressed. In order to achieve both high hardness and high ductility with an elongation of 10% or more, it can be achieved by adopting advanced production conditions such as adopting controlled rolling in a hot rolling process.
- the welding heat-affected zone is less softened and has high ductility.
- a perlite rail, a flash butt welding method of a perlite rail, and a perlite rail manufacturing method can be provided.
- Example 1 A steel with the chemical composition shown in Table 1 is formed by continuous casting of molten steel prepared by melting and alloying in a predetermined melting process (converter-RH degassing), hot rolled, accelerated cooled, and then hardened rail Manufactured. About the manufactured rail, while measuring the surface Vickers hardness, the tension test piece was extract
- the rail and the rail were joined by flash butt welding, and the hardness characteristics of the joint were also examined.
- flash butt welding straight flash is performed for 15 s and preheating is performed for 50 s.
- the final flash processing time is 10 s
- the upset time is 10 s
- approximately 20 mm upset is performed
- after 50 s is left, accelerated cooling is performed. It was.
- the residence time in the ⁇ + ⁇ temperature range was defined as the time from preheating to final flash, upset, and subsequent cooling start. Then, the residence time in the ⁇ + ⁇ temperature range was changed, and the change in hardness of the rail weld was examined.
- the rail head was cut in the rolling direction, polished, and a welded member for Vickers hardness test was collected.
- Vickers hardness is measured from the rail welded part to a part approximately 100 mm away from the rail welded part at a pitch of 1 mm, and the hardness of the softest part of the weld heat affected zone and the softened part lower than the Vickers hardness HV300 are measured.
- the softening width was determined.
- the microstructure of the weld heat affected zone was observed with a scanning electron microscope (SEM) at a magnification of 10,000 times or more, and the aspect ratio (aspect ratio) of the cementite shape was 5 or less.
- the number of relatively spherical cementite (A) was counted, and the ratio to the total amount of cementite (B) was determined by the above formula (C), which was defined as the cementite spheroidization rate.
- C the cementite spheroidization rate.
- the number of the target cementite was measured at random 100 or more, and the spheroidization rate of the cementite was obtained.
- Example 1 In Table 2, flash butt welding was performed on the rails having the chemical composition of steel A to steel K shown in Table 1, and the hardness of the most softened portion of the weld heat affected zone, the softened width indicating HV300 or less, and the cementite of the softened portion The spheroidization rate is shown.
- Table 2 in the steel (comparative example) in which the ⁇ + ⁇ temperature range is higher than 100 ° C., the hardness of the most softened portion of the weld heat affected zone is low and the softened width of the weld heat affected zone is HV300 or less. Is also wide.
- the steel (invention example) having a ⁇ + ⁇ temperature range of 100 ° C. or less which is a feature of the present application, the decrease in the hardness of the weld heat affected zone is small and the softening width is narrow.
- Example 2 Using steel I, the welding conditions during flash butt welding were varied to investigate the softening behavior of the weld. After performing straight flash for 15 s and preheating for 50 s, the processing time of the final flash was arbitrarily changed, upset time was 10 s, about 20 mm of upset was performed, and after 50 s was left, accelerated cooling was performed. The accumulated time from preheating to the start of cooling was defined as the residence time (s) in the ⁇ + ⁇ temperature range, and changes in the hardness characteristics of the heat affected zone were examined. The results are shown in Table 3. As shown in Table 3, as the residence time in the ⁇ + ⁇ temperature range becomes longer, the hardness of the most softened portion decreases and the softening width becomes HV300 or less.
- the residence time particularly in the ⁇ + ⁇ temperature range is shown.
- the hardness of the softest part was greatly reduced, and the softening width was also rapidly expanded (comparative example). This corresponds to the rapid increase in the spheroidization rate of cementite.
- the residence time in the ⁇ + ⁇ temperature range was 200 s or less, the hardness reduction and softening width of the most softened portion of the weld heat affected zone were small (invention example).
- Example 3 Steels A, C, D, H, I, J, K, and L were examined for changes in hardness and strength characteristics by changing various accelerated cooling conditions such as cooling start and stop after rail hot rolling. The results are shown in Table 4. As shown in Table 4, when the cooling start temperature is lower than 720 ° C, the cooling rate is slower than 1 ° C / s, or the cooling stop temperature is higher than 500 ° C, sufficient rail surface hardness and strength (tensile Strength, 0.2% proof stress) could not be obtained (Comparative Example). Further, when the recuperation temperature was 400 ° C. or less, some martensite was observed, the elongation was low, and the ductility was lowered (Comparative Example).
- Example 4 For steel A and steel H, the controlled rolling and subsequent accelerated cooling conditions were changed to examine the hardness and tensile properties. The results are shown in Table 5. As shown in Table 5, by performing controlled rolling with a surface area reduction rate of 20% or more at a temperature of 1000 ° C. or less, the elongation is stably 12% or more with almost the same hardness and strength, and more excellent. It showed ductility (invention example). However, when the cooling start temperature is lower than 720 ° C., the hardness and strength are decreased, and the wear resistance, which is the original purpose, is inhibited (Comparative Example). Care must be taken in lowering the temperature.
- the present invention can be applied to a high hardness and high toughness pearlite rail, a flash butt welding method of a pearlite rail, and a method of manufacturing a pearlite rail with little softening of the heat affected zone.
Abstract
Description
(2)720℃を超えると、フェライト(α)がオーステナイト(γ)に変態するようになり、フェライト(α)、セメンタイト(θ)、オーステナイト(γ)の三相が共存する温度域となる。
(3)さらに温度が730℃以上に上昇すると、セメンタイト(θ)、オーステナイト(γ)の二相となる。棒状のセメンタイト(θ)は、溶接に伴う温度上昇とともに、界面エネルギーを減らす方向に形状は変化するので、オーステナイト(γ)とセメンタイト(θ)の二相温度域まで加熱される部分では、セメンタイト(θ)は分断、球状化する。
(4)さらに温度が高くなるとオーステナイト(γ)単相となる。
(5)さらに高温では溶融する。
Cはパーライトレールに対してはセメンタイトを形成し硬さや強度を高め、耐摩耗性を向上させる重要な元素である。しかし、0.70%未満のC量ではそれらの効果が小さいことから、C量の下限を0.7%とした。一方、C量の増加はセメンタイト量の増加を意味しており、硬さや強度の上昇が期待できるが延靱性は逆に低下する。さらに、C量の増加はγ+θ温度範囲を拡大させ、溶接熱影響部の軟化を助長する。これらの悪影響を考慮して、C量の上限は1.0%とした。C量の好ましい範囲は、0.70~0.95%である。
Siはレール母材には脱酸素材およびパーライト組織強化のために添加するが、0.1%未満の量ではこれらの効果が小さい。一方、1.5%を超える量のSiの添加は、溶接時の接合不良が発生し易く、表面脱炭も促進し、レール母材にマルテンサイトも生成し易くするので、Si量の上限を1.5%とした。好ましくは、Si量は0.2~1.3%の範囲とする。
Mnはパーライト変態温度を低下させ、パーライトラメラー間隔(パーライト組織のラメラー間隔)を緻密にする効果があるので、レール内部まで高硬度を維持するために有効な元素であるが、0.01%未満の量ではその効果が小さい。一方、1.5%を超える量のMnの添加は、パーライトの平衡変態温度(TE)を低下させるとともにマルテンサイト変態が起こり易くなるので、Mn量の上限を1.5%とした。好ましくは、Mn量は0.3~1.3%の範囲とする。
0.035%を超える量のPは延靱性を低下させる。そのため、P量の上限は0.035%以下とする。好適範囲としてはP量の上限は0.025%とする。一方、P量の下限については、特殊精錬などを行うと溶製のコスト上昇を招くことからP量の下限は0.001%とした。
Sは圧延方向に伸展した粗大なMnSを形成して、延靱性や遅れ破壊特性を低下させる。S量の増加に伴いMnSの粗大化や個数が増加するため、これらを考慮して0.030%をS量の上限とした。一方、S量の下限については溶製処理時間の増大など溶製時のコストアップが著しいので、S量の下限は0.0005%とした。好ましくは、S量は0.001~0.020%の範囲とする。
Crは、平衡変態温度(TE)を上昇させ、パーライトラメラー間隔の微細化に寄与して、硬さや強度を上昇させる。そのため、0.1%以上の量のCrの添加を必要とする。一方、2.0%を超える量のCrの添加は、溶接欠陥の発生を増加させ(溶接性を低下させ)、焼入れ性を増加させマルテンサイトの生成を促進させるので、Cr量の上限を2.0%とした。より好ましくは、Cr量は0.2%~1.5%の範囲とする。
Cuは固溶強化により一層の高硬度化を図ることができる元素である。しかし、この効果を期待するためには0.01%以上の量のCuの添加を必要とする。一方、1.0%を超える量のCuの添加は連続鋳造時や圧延時に表面割れを生じ易くすることから、Cu量の上限を1.0%とする。Cu量は、0.05~0.6%の範囲とすることがよりいっそう好ましい。
Niは靭性や延靱性を向上させる有効な元素である。また、Cuと複合添加することでCu割れを抑制する有効な元素であるため、Cuを添加する場合にもNiを添加することが望ましい。但し、0.01%未満のNi量ではこれらの効果が認められないことから、Ni量の下限を0.01%とした。一方、0.5%を超える量のNiの添加は、焼入れ性を高めマルテンサイトの生成を促進させるので、Ni量の上限を0.5%とした。より好ましくは、Ni量は0.05~0.3%の範囲とする。
Moは高強度化に有効な元素であるが、0.01%未満の量ではその効果が小さいので、Mo量の下限を0.01%とした。一方、0.5%を超える量のMoの添加は焼入れ性を高める結果としてマルテンサイトが生成するため、靭性や延靱性を極端に低下させる。そのため、上限は0.5%とした。好ましくは、Mo量は0.05~0.3%の範囲とする。
Vは、VCあるいはVNなどを形成してフェライト中へ微細に析出し、フェライトの析出強化を通して高強度化に有効な元素である。また、水素のトラップサイトとしても機能し、遅れ破壊を抑制する効果も期待できる。そのためには、0.001%以上の量のVの添加を必要とする。一方、0.1%を超える量のVの添加はそれらの効果を飽和させ甚だしく合金コストを上昇させるので、V量の上限を0.15%とした。好適範囲としては、V量は0.005~0.12%の範囲とする。
Nbはオーステナイトの未再結晶温度を上昇させ、圧延時のオーステナイト中への加工歪の導入によるパーライトコロニーやブロックサイズの微細化に有効で、延靱性の向上に対して有効な元素である。その効果を期待するためには、0.001%以上の量のNbの添加を必要とする。一方、0.030%を超える量のNbの添加は、凝固過程でNb炭窒化物を晶出させ、清浄性を低下させるので、Nb量の上限を0.030%とした。好ましくは、Nb量は0.003~0.025%の範囲とする。
γ+θ温度範囲が100℃を超えると、レールのフラッシュバット溶接時にセメンタイトの球状化が促進し、溶接熱影響部の最軟化部分の硬さがHV370以下に低下し、HV300以下となる部分の軟化幅も拡大する。そのため、γ+θ温度範囲は100℃以下とする必要がある。γ+θ温度範囲の下限については特に規定しないが、γ+θ温度範囲が10℃未満では、レール母材の硬さや強度が低下するので、γ+θ温度範囲の下限は10℃とすることが望ましい。γ+θ温度範囲の好適範囲は10~90℃である。なお、γ+θ温度範囲については、熱力学へ移行計算ツールである「Thermo-calc」などの計算ツールにて成分系に応じたFe-C平衡状態図を作成し、γ+θ温度およびγ+θ温度範囲を求めることとする。必要に応じて、セメンタイトの球状化の状態を熱サイクル試験を行なって調べても構わない。
レール頭頂は、車輪との転動接触により、摩耗や転動疲労が生じる。その際、レール母材、レール溶接部ともに、車輪と接触するので、双方に摩耗や転動疲労が生じる。このレール溶接部において溶接熱影響部の軟化や軟化部分の範囲が大きいと、軟化部分がレール母材に対して早く摩耗する(偏摩耗)。そうなると、レール母材と溶接熱影響部の軟化部分との間に摩耗差が生じるので、軟質な溶接熱影響部の最も軟化する部分(最軟化部分)に摩耗による窪みが形成され、騒音や振動を増加させる。さらには、割折する懸念もある。そのため、極力溶接熱影響部の軟化は小さいことが望ましい。しかしながら、これまで冶金的説明を行った溶接熱影響部の最軟化部分の他に、溶接時にオーステナイト(γ)とセメンタイト(θ)に加熱される部分は必ず存在するため、軟化部分を全くなくすことは困難である。ただし、レール溶接部の最軟化部分の硬さをHV370以上とし、硬さがHV300以下となる溶接熱影響部の軟化部分の幅(軟化幅)を15mm以下とすることにより、レール溶接部のレール母材との偏摩耗が小さくなり、騒音や振動が軽減される。このことから、溶接部の最軟化部分の硬さをHV370以上とし、硬さがHV300以下となる溶接熱影響部の軟化幅を15mm以下とした。
溶接時にγ+θ温度域に加熱保持された部分のセメンタイトが球状化し、軟化やその軟化幅が大きくなるため、セメンタイトの短辺と長辺の比(アスペクト比)が5以下であるセメンタイトの個数割合をセメンタイト総量に対して50%以下とする必要がある。
熱間圧延後、720℃以上の温度から加速冷却を開始する必要がある。720℃よりも低い温度から加速冷却を行うと、過冷度(ΔT)が小さくなり硬さや強度が低下する。したがって、加速冷却開始温度は720℃以上とする必要がある。好ましくは、加速冷却開始温度は730℃以上とする。
加速冷却は、1℃/s~10℃/sの冷却速度で加速冷却を行う必要がある。冷却速度が1℃/s未満では、パーライト変態温度が上昇し、過冷度(ΔT)が小さくなるためにパーライトラメラー間隔が広くなり、硬さや強度が低下する。一方、10℃/sを超える冷却速度は、レール表面にマルテンサイトが生成され易くなり、延靱性や疲労特性を低下させる。そのため、冷却速度は1~10℃/sの範囲で行う必要がある。冷却速度の好適範囲は、1.5℃/s~7℃/sである。
加速冷却の冷却停止温度は500℃以下とする必要がある。冷却停止温度が500℃よりも高い場合には、パーライト変態の途中で加速冷却を停止することになり、特にレール内部の硬さの低下が大きくなる。そのため、冷却停止温度は500℃以下とする必要がある。冷却停止温度の下限は特に規定しないが、マルテンサイト変態を防止するために、250℃以下まで加速冷却することは避けるべきである。そのため、望ましくは、冷却停止温度の範囲は500℃~250℃とする。
加速冷却を500℃以下までした後、放冷させ、レール表面は400℃以上に復熱させる必要がある。レール表面の復熱が400℃未満の場合、レールの極表層に一部マルテンサイトが生成され、疲労特性を低下させる。したがって、レール表面の復熱温度は400℃以上とすることが必要である。
一般に、レールの圧延は、ブレークダウン圧延機、粗圧延機、仕上圧延機にて熱間圧延されるが、粗圧延機、仕上圧延機での圧延過程において1000℃以下で減面率が20%以上の圧延を行うことにより、パーライトブロックやコロニーサイズが微細化し、一層の延靱性向上が期待できる。1000℃以上で減面率が20%以上の圧延や、1000℃以下でも減面率が20%未満の圧延では、パーライトブロックやコロニーサイズの微細化が不十分で、レール母材の延靱性の向上には不十分である。
圧延仕上温度は800℃以上とする必要がある。圧延仕上温度が800℃未満になると、その後に引き続いて行う加速冷却の際の冷却開始温度が低下するために、微細ラメラーをもつパーライト組織の形成が不十分となり、硬さや強度の低下を招く。したがって、圧延仕上温度は800℃以上が必要である。望ましくは850℃以上である。
レール頭頂には、車輪との接触による摩耗や転動疲労に伴って、表面亀裂の発生・伝播による剥離損傷が生じる。特に、レールの表面の硬さが低い場合には、耐摩耗性を低下させる。鉱山鉄道や貨物鉄道が主体の鉄道では、レールに係る応力が高いので摩耗量が多くなり、レール寿命を低下させることになる。レールの表面の硬さがHV370未満ではレールの摩耗が顕著のため、レールの表面の硬さはHV370以上を必要とする。好ましくは、レールの表面の硬さはHV380以上とする。
基本的に、0.5インチ深さの引張強度は硬さと同等であり、レールの耐摩耗性を向上させるためには、1300MPa以上の引張強度が必要である。
0.5インチ深さの0.2%耐力は、827MPa以上を必要とする。レールと車輪との接触において微視的なすべりが発生すると、レールの極表層に塑性流動を生じる。その塑性流動層から亀裂が発生、伝播して損傷する場合があるので、塑性流動を極力抑制する必要がある。そのためには、レールの0.2%耐力は高いほうがよく、827MPa以上を必要とする。さらに、転動疲労に対しても0.2%耐力は高いほうが望ましく、827MPa以上の耐力であれば重貨物鉄道用のレールで十分な疲労特性を発揮することが期待できる。
疲労クラックの生成や成長により、レールが最終的には破断する大きな事故になる懸念がある。その破断を抑制するためには、延靱性(伸び)が高いことが望ましい。しかしながら、パーライト組織を有するレールで耐久性を向上させる場合には、高硬度と高延靱性とを両立させる必要がある。重貨物鉄道のような鉄道に敷設される耐摩耗性が重視される高硬度のパーライトレールでは、その伸びは10%以上あれば、概ね重大な事故を抑えることができる。なお、高硬度で10%以上の伸びをもつ高い延靱性を両立させるためには、制御圧延を熱間圧延工程で採用するなど高度な製造条件を採用することで達成することができる。
所定の溶製プロセス(転炉-RH脱ガス)で溶製、合金調整した溶鋼を連続鋳造にて表1に示す化学組成を有するブルームとし、熱間圧延、加速冷却したあと、高硬度のレールを製造した。製造したレールについては表面のビッカース硬さを測定するとともに、レール頭頂より10mm深さより引張試験片を採取し、引張試験を行った。顕微鏡サンプルを採取し、レール表面近傍および0.5インチ深さ部の顕微鏡観察および走査電子顕微鏡による組織観察を行った。
表2に、表1に示す鋼Aから鋼Kの化学組成を有するレールについてフラッシュバット溶接を行い、溶接熱影響部の最軟化部分の硬さ、HV300以下を示す軟化幅および最軟化部分のセメンタイト球状化率を示す。表2に示すように、γ+θ温度範囲が100℃よりも高い鋼(比較例)では、溶接熱影響部の最軟化部分の硬さが低く、かつ、HV300以下となる溶接熱影響部の軟化幅も広い。一方、本願の特徴であるγ+θ温度範囲が100℃以下の鋼(発明例)については、溶接熱影響部の硬さの低下が小さく、軟化幅も狭い。
鋼Iを用いて、フラッシュバット溶接時の溶接条件を変化させて溶接部の軟化挙動を調べた。ストレートフラッシュを15s、予熱50sを行った後、最終フラッシュの処理時間を任意に変化させた後、アップセット時間10s、約20mmのアップセットを行い、50s放置後、加速冷却を行った。予熱から冷却開始までの積算時間をγ+θ温度域での滞留時間(s)として、溶接熱影響部の硬さ特性の変化を調べた。その結果を表3に示す。表3に示すように、γ+θ温度域での滞留時間が長くなるにつれて最軟化部分の硬さは低下し、HV300以下となる軟化幅も拡大する傾向を示すが、特にγ+θ温度域での滞留時間が200sを超えると最軟化部分の硬さが大きく低下し、軟化幅も急激に拡大した(比較例)。これは、セメンタイトの球状化率が急激に増加したことに対応している。一方、γ+θ温度域での滞留時間が200s以下では溶接熱影響部の最軟化部分の硬さ低下や軟化幅は小さかった(発明例)。
鋼A,C,D,H,I,J,K,Lについてレール熱間圧延後の冷却開始や停止などの加速冷却条件を種々変化させて、硬さ、強度特性の変化を調べた。その結果を表4に示す。表4に示すように、冷却開始温度が720℃より低い場合、冷却速度が1℃/sより遅い場合、冷却停止温度が500℃より高い場合には、十分なレール表面の硬さや強度(引張強度、0.2%耐力)が得られなかった(比較例)。また、復熱温度が400℃以下では一部マルテンサイトが観測され伸びは低く延靱性が低下した(比較例)。冷却開始温度、冷却速度、冷却停止温度および復熱温度を規定値内にすることで、HV370以上のレール表面硬さ、TS1300MPa以上、0.2%YS827MPa以上、El10%以上の高強度のレールが得られた(発明例)。
鋼Aと鋼Hについて制御圧延とその後の加速冷却条件を変化させて、硬さと引張特性について調べた。その結果を表5に示す。表5に示すように、1000℃以下の温度で減面率20%以上の制御圧延を行うことで、ほぼ同じ硬さや強度で、安定して12%以上の伸びを呈しており、いっそう優れた延靭性を示した(発明例)。しかしながら、冷却開始温度が720℃を下回ると硬さや強度を逆に低下させ、本来の趣旨である耐摩耗性を阻害する結果となった(比較例)ことから、過度な低温圧延による冷却開始温度の低温化には注意する必要がある。
Claims (10)
- 質量パーセントで、C:0.70~1.0%、Si:0.1~1.5%、Mn:0.01~1.5%、P:0.001~0.035%、S:0.0005~0.030%、Cr:0.1~2.0%を含有し、残部がFeおよび不可避的不純物であって、γ+θ温度範囲が100℃以下であるパーライトレール。
- Cu:0.01~1.0%、Ni:0.01~0.5%、Mo:0.01~0.5%、V:0.001~0.15%、Nb:0.001~0.030%の1種または2種以上をさらに含有し、残部がFeおよび不可避的不純物であって、γ+θ温度範囲が100℃以下である請求項1に記載のパーライトレール。
- 質量パーセントで、C:0.70~1.0%、Si:0.1~1.5%、Mn:0.01~1.5%、P:0.001~0.035%、S:0.0005~0.030%、Cr:0.1~2.0%を含有し、残部がFeおよび不可避的不純物であって、γ+θ温度範囲が100℃以下であり、
γ+θ温度域における滞留時間が200s以下であるフラッシュバット溶接を施した場合に形成される溶接熱影響部においてビッカース硬さHV300以下である軟化部分の幅が15mm以下、最軟化部分の硬さがHV270以上であるパーライトレール。 - Cu:0.01~1.0%、Ni:0.01~0.5%、Mo:0.01~0.5%、V:0.001~0.15%、Nb:0.001~0.030%の1種または2種以上をさらに含有し、残部がFeおよび不可避的不純物であって、γ+θ温度範囲が100℃以下であり、溶接した際の溶接熱影響部においてビッカース硬さHV300以下である軟化部分の幅が15mm以下、最軟化部分の硬さがHV270以上である請求項3に記載のパーライトレール。
- 溶接熱影響部の最軟化部分のセメンタイトについて、その短辺と長辺の比(アスペクト比)が5以下であるセメンタイトの個数割合がセメンタイト総量に対して50%以下である請求項1~4のいずれか一項に記載のパーライトレール。
- パーライトレールをフラッシュバット溶接するに際し、アップセットおよびその後の冷却において、γ+θ温度域における滞留時間を200s以下とし、溶接熱影響部の軟化部分の幅を15mm以下、最軟化部分の硬さをHV270以上とするパーライトレールのフラッシュバット溶接方法。
- 請求項1~4のいずれか一項に記載の化学成分を有するレール素材を用いて熱間圧延によりレールを製造するパーライトレールの製造方法であって、
熱間圧延後、720℃以上の温度から加速冷却を開始し、500℃以下まで1℃/s~10℃/sの冷却速度で加速冷却を行い、その後放冷し、レール表面を400℃以上まで復熱させるパーライトレールの製造方法。 - 請求項1~4のいずれか一項に記載の化学成分を有するレール素材を用いて熱間圧延によりレールを製造するパーライトレールの製造方法であって、
1000℃以下で減面率20%以上、圧延仕上温度を800℃以上の熱間圧延を行い、その後、720℃以上から加速冷却を開始し、500℃以下まで1℃/s~10℃/sの冷却速度で加速冷却を行い、その後放冷し、レール表面を400℃以上まで復熱させるパーライトレールの製造方法。 - 前記製造されたパーライトレールにおいて、レール頭頂の表面の硬さをHV370以上、引張強度を1300MPa以上、0.2%耐力を827MPa以上とする請求項7に記載のパーライトレールの製造方法。
- 前記製造されたパーライトレールにおいて、レール頭頂の表面の硬さをHV370以上、引張強度を1300MPa以上、0.2%耐力が827MPa以上、伸びを10%以上とする請求項8に記載のパーライトレールの製造方法。
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US11401591B2 (en) * | 2015-12-15 | 2022-08-02 | Jfe Steel Corporation | Method for selecting rail steel and wheel steel |
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CN113618193B (zh) * | 2021-08-17 | 2023-06-30 | 攀钢集团攀枝花钢铁研究院有限公司 | 75kg/m过共析钢轨与共析钢轨气压焊接方法及焊接件 |
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Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57198216A (en) * | 1981-05-27 | 1982-12-04 | Nippon Kokan Kk <Nkk> | Manufacture of high-strength rail |
JPS57207117A (en) * | 1981-06-17 | 1982-12-18 | Nippon Kokan Kk <Nkk> | Joining method for heat treated rail |
JP2008050687A (ja) * | 2006-07-24 | 2008-03-06 | Nippon Steel Corp | 耐摩耗性および延性に優れたパーライト系レールの製造方法 |
JP2009108397A (ja) * | 2007-03-28 | 2009-05-21 | Jfe Steel Corp | 耐摩耗性と耐疲労損傷性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 |
JP2009235515A (ja) * | 2008-03-27 | 2009-10-15 | Jfe Steel Corp | 耐遅れ破壊性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 |
JP2010077481A (ja) * | 2008-09-25 | 2010-04-08 | Jfe Steel Corp | 耐摩耗性と耐疲労損傷性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 |
JP2010100937A (ja) * | 2008-09-25 | 2010-05-06 | Jfe Steel Corp | フラッシュバット溶接継手特性に優れた内部高硬度型パーライト鋼レールおよびその溶接方法 |
-
2012
- 2012-04-25 CA CA2869964A patent/CA2869964C/en active Active
- 2012-04-25 US US14/396,822 patent/US20150152516A1/en not_active Abandoned
- 2012-04-25 BR BR112014026521-6A patent/BR112014026521B1/pt active IP Right Grant
- 2012-04-25 AU AU2012378562A patent/AU2012378562B2/en active Active
- 2012-04-25 WO PCT/JP2012/061147 patent/WO2013161026A1/ja active Application Filing
Patent Citations (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57198216A (en) * | 1981-05-27 | 1982-12-04 | Nippon Kokan Kk <Nkk> | Manufacture of high-strength rail |
JPS57207117A (en) * | 1981-06-17 | 1982-12-18 | Nippon Kokan Kk <Nkk> | Joining method for heat treated rail |
JP2008050687A (ja) * | 2006-07-24 | 2008-03-06 | Nippon Steel Corp | 耐摩耗性および延性に優れたパーライト系レールの製造方法 |
JP2009108397A (ja) * | 2007-03-28 | 2009-05-21 | Jfe Steel Corp | 耐摩耗性と耐疲労損傷性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 |
JP2009235515A (ja) * | 2008-03-27 | 2009-10-15 | Jfe Steel Corp | 耐遅れ破壊性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 |
JP2010077481A (ja) * | 2008-09-25 | 2010-04-08 | Jfe Steel Corp | 耐摩耗性と耐疲労損傷性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 |
JP2010100937A (ja) * | 2008-09-25 | 2010-05-06 | Jfe Steel Corp | フラッシュバット溶接継手特性に優れた内部高硬度型パーライト鋼レールおよびその溶接方法 |
Cited By (3)
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US11401591B2 (en) * | 2015-12-15 | 2022-08-02 | Jfe Steel Corporation | Method for selecting rail steel and wheel steel |
JP2017115229A (ja) * | 2015-12-25 | 2017-06-29 | Jfeスチール株式会社 | レール |
WO2023080135A1 (ja) * | 2021-11-05 | 2023-05-11 | 日本製鉄株式会社 | 溶接レール |
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US20150152516A1 (en) | 2015-06-04 |
BR112014026521A2 (pt) | 2017-06-27 |
AU2012378562A1 (en) | 2014-11-13 |
BR112014026521B1 (pt) | 2019-06-18 |
AU2012378562B2 (en) | 2016-07-07 |
CA2869964C (en) | 2017-07-04 |
CA2869964A1 (en) | 2013-10-31 |
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