US20150322553A1 - Bainitic steel rail containing trace amounts of carbides and producing method of the same - Google Patents

Bainitic steel rail containing trace amounts of carbides and producing method of the same Download PDF

Info

Publication number
US20150322553A1
US20150322553A1 US14/702,188 US201514702188A US2015322553A1 US 20150322553 A1 US20150322553 A1 US 20150322553A1 US 201514702188 A US201514702188 A US 201514702188A US 2015322553 A1 US2015322553 A1 US 2015322553A1
Authority
US
United States
Prior art keywords
steel rail
carbides
cooling
bainitic
steel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
US14/702,188
Other languages
English (en)
Inventor
Zhenyu Han
Ming Zou
Jihai JIA
Hua Guo
Dadong Li
Yong Deng
Chunjian WANG
Jun Yuan
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Original Assignee
Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd filed Critical Pangang Group Panzhihua Iron and Steel Research Institute Co Ltd
Assigned to PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INSTITUTE CO., LTD. reassignment PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INSTITUTE CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DENG, YONG, GUO, HUA, HAN, ZHENYU, JIA, JIHAI, LI, DADONG, WANG, CHUNJIAN, YUAN, JUN, ZOU, MING
Publication of US20150322553A1 publication Critical patent/US20150322553A1/en
Abandoned legal-status Critical Current

Links

Images

Classifications

    • 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
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • 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
    • C21D6/005—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
    • 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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • 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
    • 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
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • 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
    • C21D2211/004—Dispersions; Precipitations

Definitions

  • the present invention relates to a bainitic steel rail containing trace amounts of carbides and a method for producing the bainitic steel rail containing trace amounts of carbides.
  • one method is to further increase the carbon content in the rail steel and add alloying elements in an appropriate amount as supplement, to give full play to the wear resistance improving effect of carbon in the steel rails, and obtain better toughness matching and over-all properties of the steel rails through a post-rolling cooling process;
  • the other method is to utilize bainitic steel rails with high alloy content and obtain bainitic steel rails with a high wear resistance property by controlling a post-rolling cooling process, so as to improve the wear resistance property while giving full play to the outstanding contact fatigue resistance.
  • the rail head part has 230-320 of Vickers hardness, and can't effectively resist the wheel-rail wearing owing to the low hardness; consequently, the steel rail has to be replaced early before it reaches its design life, because it is worn severely.
  • the steel rails disclosed in the patent documents CN1101856C, CN1219904C, and CN1012906B, etc. are similar to the steel rail described above.
  • patent document CN1086743C a bainitic steel rail that has high surface fatigue damage resistance and high wearing resistance performance is disclosed.
  • the microscopic structure of the bainitic steel rail is characterized in: based on the total area of a given cross section of the bainitic structure, the total area of carbides with a major axis within 100 nm-1,000 nm range accounts for 10-50%. That technique has the following obvious drawbacks: as a hard phase in the steel, the carbides account for a percentage that is too high, and consequently the cracks formed in the steel rail develop preferentially along the carbides under stress, resulting in fatigue damages such as cracking and peeling, or even fractures of the steel rail which will endanger operation safety.
  • the present invention provides a bainitic steel rail that has outstanding wear resistance and fatigue damage resistance properties and a producing method of the same.
  • the size and percentage of the carbides in bainitic steel rails have apparent influences on the wear resistance and service life of the steel rails.
  • the steel rail is subjected to the reciprocating action of complex stress exerted by the wheels, and the rail head wheel-rail contact part of steel rail will be worn continuously by the friction force created between the steel rail and the wheels.
  • the bainitic ferrite in the steel rail is a soft phase in the steel, and it still can not have enough strength to resist the wearing by the wheels though it has been strengthened in the accelerated cooling process after rolling.
  • the carbides which is a hard phase in the steel, will gradually precipitate from the bainitic ferrite and concentrate as the surface layer of rail head is worn in the service process, and thereby will resist the stress exerted by the wheels together and can improve the wear resistance of the steel.
  • the inventor of the present invention has found: the carbides that precipitate from the bainitic ferrite matrix are in rod-shaped or strip-shaped, in length of not greater than 0.5 ⁇ m, and are oriented to a direction at a 50-70° included angle from the direction of the major axis of ferrite plates, and these carbides can effectively improve the wear resistance property of the steel rail, with little adverse effect to the rolling contact fatigue resistance property of the steel rail.
  • the present invention provides a bainitic steel rail containing trace amounts of carbides, wherein, the bainitic steel rail mainly consists of bainitic structures, the carbides have a length of 0.05-0.5 ⁇ m, the major axis of carbides is oriented to a direction at a 50-70° included angle from the direction of the major axis of bainitic ferrite plates, and the carbides account for 1%-5% by volume.
  • the present invention further provides a method for producing a bainitic steel rail containing trace amounts of carbides, comprising: cooling a steel rail with residual heat after finish rolling by air cooling, till the temperature at the center of the rail head tread reaches 420-450° C.; cooling the rail head part of the steel rail by accelerated cooling at a 2.0-5.0° C./s cooling rate, till the temperature at the center of the rail head tread reaches 220-240° C.; loading the steel rail into a tempering furnace and tempering at 300-350° C. for 4-6 h; then, cooling the steel rail by air cooling to the room temperature.
  • the FIGURE shows the microscopic structure of the bainitic steel rail containing trace amounts of carbides provided in the present invention under a transmission electron microscope (TEM) after the thickness is reduced by twin-jet electropolishing.
  • TEM transmission electron microscope
  • the present invention provides a bainitic steel rail containing trace amounts of carbides, wherein, the bainitic steel rail mainly consists of bainitic structures, the carbides have a length of 0.05-0.5 ⁇ m, the major axis of carbides is oriented to a direction at a 50-70° included angle from the direction of the major axis of bainitic ferrite plates, and the carbides account for 1%-5% by volume.
  • the inventor of the present invention has found: if the percentage of carbides is too high, e.g., higher than 5%, though the wear resistance property of the steel rail can be improved effectively, cracks may occur easily in the steel rail under the stress exerted by the wheels and the steel rail, and the cracks will developed preferentially along the carbides in the steel; consequently, the steel rail will fracture in a short time, and the service safety can't be ensured.
  • the major axis direction of the carbides is at 50-70° included angle from the major axis of the bainitic ferrite plates, which is advantageous for ensuring the fatigue damage resistance property of the steel rail will not be degraded even after plastic deformation occurs at the wheel-rail contact part.
  • the bainitic steel rail contains: 0.15 wt %-0.30 wt % C, 1.00 wt %-1.80 wt % Si, 1.50 wt %-2.50 wt % Mn, 0.50 wt %-1.00 wt % Cr, 0.20 wt %-0.50 wt % Mo, and Fe that accounts for the remaining content, and the total weight percentage of Mn and Cr meets 2.2% ⁇ Mn+Cr ⁇ 3.0%.
  • Carbon (C) is the most important element for bainitic steel to obtain outstanding toughness matching and overall mechanical properties.
  • the carbon content is lower than 0.15 wt %, it is unable to give full play to the strengthening effect, and the rigidity of the steel rail will be too low, and consequently the carbide percentage in the steel and the wear resistance property of the steel can't be ensured;
  • the carbon content is higher than 0.30 wt %, through the process described in the present invention, the strength of the steel is too high, while the toughness and plasticity are too low; consequently, the contact fatigue resistance of the steel is severely affected because the percentage of carbides is too high, and the application safety of the steel rail is compromised. Therefore, the carbon content is confined to 0.15-0.30 wt %.
  • silicon (Si) As a major additional element in steel, silicon (Si) usually exists in ferrite in the form of solid solution, and can improve the strength of the structure.
  • Si silicon
  • the strengthening effect is not significant because the concentration of solid solution is low; on the other hand, fine carbides can't be obtained, and consequently the structural control objective of the present invention can't be attained; when the silicon content is higher than 1.80 wt %, the carbide precipitation will be fully inhibited; instead, residual austenite will exist, and surface defects may easily occur, consequently, the smoothness of train operation can't be ensured. Therefore, the silicon content is confined to 1.00-1.80 wt %.
  • Manganese (Mn) can significantly decrease the initial transition temperature of bainitic structure, improve the hardness of carbides, and is an important additional element in bainitic steel.
  • the inventor has found: when the manganese content is lower than 1.50 wt %, it will be difficult to attain the effect of improving carbide hardness; when the manganese content is higher than 2.50 wt %, the carbide hardness will be too high, and the fatigue resistance property of the steel rail will be severely degraded. Therefore, the manganese content is confined to 1.50-2.50 wt %.
  • chromium can bond with carbon in steel to form a variety of carbides; in addition, chromium is helpful for uniform distribution of carbons in steel, and can decrease carbide size, and thereby improve the wear resistance property of the steel rail.
  • the chromium content is lower than 0.50 wt %, the hardness and percentage of the carbides formed in steel will be low, and the carbides will concentrate in the form of flakes, which is adverse to the service performance of the steel rail; when the chromium content is higher than 1.00 wt %, the percentage of martensite in steel will be increased severely, and consequently the service safety of the steel rail can't be ensured. Therefore, the chromium content is confined to 0.50-1.00 wt %.
  • Molybdenum (Mo) has a remarkable effect for decreasing the initial transition temperature of bainitic structure, and is advantageous for stabilizing and strengthening bainitic structure.
  • Molybdenum content is lower than 0.20 wt %, it will be difficult to attain the above-mentioned effects; when the molybdenum content is higher than 0.50 wt %, the transition efficiency of bainitic structure will be severely decreased, and consequently an ideal bainitic structure can't be obtained in the accelerated cooling process. Therefore, the molybdenum content is confined to 0.20-0.50 wt %.
  • the manganese content and chromium content should meet 2.2 wt % ⁇ Mn+Cr ⁇ 3.0 wt %.
  • Mn and Cr have similar effects in bainitic steel; when Mn+Cr ⁇ 2.20 wt %, the strength, size, and percentage of carbides in steel can't meet the requirement described in the present invention; in addition, the hardness of carbides is low, and a moderate wear resistance property can't be obtained; when Mn+Cr>3.00 wt %, on the one hand, the hardness of carbides will be too high; on the other hand, severe segregation will occur locally in the steel rail, and consequently the uniformity of bainitic structure and the performance of bainitic structure in the steel rail can't be ensured. Therefore, a condition of “2.2 wt % ⁇ Mn+Cr ⁇ 3.0 wt %” must be met.
  • Mn+Cr refers to the sum of Mn content
  • the present invention further provides a method for producing a bainitic steel rail containing trace amounts of carbides, comprising: cooling a steel rail with residual heat after finish rolling by air cooling, till the temperature at the center of the rail head tread reaches 420-450° C.; cooling the rail head part of the steel rail by accelerated cooling at a 2.0-5.0° C./s cooling rate, till the temperature at the center of the rail head tread reaches 220-240° C.; loading the steel rail into a tempering furnace and tempering at 300-350° C. for 4-6 h; then, cooling the steel rail by air cooling to the room temperature.
  • a steel rail with residual heat after finish rolling is utilized, the rail head part of the steel rail is cooled by accelerated cooling at a 2.0-5.0° C./s cooling rate; when the temperature at the center of the rail head tread drops to 220° C.-240° C., the steel rail is loaded into a tempering furnace and is tempered at 300-350° C.
  • rod-shaped carbides can precipitate from the bainitic ferrite matrix, wherein the rod-shaped carbides are in 0.05-0.5 ⁇ m length and oriented to a direction at a 50-70° included angle from the major axis of the bainitic ferrite plates, and account for 1%-5% by volume.
  • the steel rail with residual heat after finish rolling can be produced with a common method in the art; for example, the method can comprise: processing a steel material with appropriate chemical composition by smelting in a converter or electric furnace, LF refining, RH or VD vacuum treatment, and casting, to produce a continuous casting steel billet with appropriate cross sectional dimensions; then, the steel billet is loaded into a walking beam furnace and heated up to 1200-1300° C., and is held at that temperature for 2 h or longer time; next, the steel billet is rolled to a steel rail with required cross sectional dimensions; here, the finish rolling temperature of the steel rail is 850-950° C.
  • the rail steel with residual heat after finish rolling is erected on a roller way and held in the air for air cooling; when the temperature of the surface layer of steel rail head drops to 420-450° C., an accelerated cooling medium is applied to the top surface and both sides of the rail head.
  • the accelerated cooling medium can be a commonly used cooling medium in the art.
  • the accelerated cooling medium can be selected from at least one of compressed air, water-air mixture, and oil-gas mixture.
  • the phase transition temperature of bainitic steel rails is usually within the range of 350-400° C.
  • the accelerated cooling is initiated from the temperature range of austenitic phase region, longer cooling time will be required and more cooling medium energy will be consumed, since the initial accelerated cooling temperature is far away from the phase transition temperature; more importantly, in the accelerated cooling process, the heat from the core part of rail head and the rail web part will diffuse towards the surface layer of rail head by heat transfer, while the surface layer of rail head is subjected to accelerated cooling by the external cooling medium; consequently, the rail head part can't accomplish phase transition at a higher super-cooling degree, ultimately the rigidity on the cross section of rail head will decrease gradually from the surface layer to the core part, and the steel rail can't be hardened entirely.
  • the initial cooling temperature As 420-450° C., the following benefit can be obtained: initiating the accelerated cooling in the temperature range from the austenitic phase region to 450° C. has little contribution to the improvement of the overall performance of the steel rail.
  • both the temperature of the rail web and the temperature of the rail base are lower than 480° C.
  • the temperature of the surface layer of rail head will be decreased significantly, while the heat from the core part of rail head is difficult to effectively replenish the heat loss in the surface layer; in addition, since the initial cooling temperature is close to the phase transition point, the entire cross section of rail head, in particular to core part of rail head, can accomplish phase transition at a higher super-cooling degree.
  • the reason why the cooling rate is set to 2.0-5.0° C./s in that process is as follows: if the cooling rate is lower than 2.0° C./s, the temperature of the surface layer of rail head can't be cooled down quickly, and the cooling effect can't be transferred effectively to the core part; in addition, the heat from the core part will anti-replenish to the surface layer, which is adverse to the improvement of the overall performance of the steel rail; more importantly, the carbides in the steel rail can't precipitate sufficiently, and consequently the object of the present invention can't be attained; if the cooling rate is higher than 5.0° C./s, more martensite will be produced because the surface layer is cooled down too quickly, consequently, the rigidity of the steel rail will be too high; though the martensite can be converted to tempered martensite partially through the follow-up tempering process, residual martensite will remain and form martensitic structures at the room temperature finally, which will be adverse to the safe application of the steel rail.
  • the accelerated cooling is stopped when the surface layer of steel rail is cooled down to 220-240° C.
  • the reason why the final temperature of accelerated cooling is set to 220-240° C. is as follows: if the final cooling temperature is higher than 240° C., though fine bainitic structures have been obtained in the surface layer of rail head, coarse bainitic structures will be formed in the core part of rail head owing to the high temperature, and the coarse bainitic structures will influence the performance of the steel rail at the room temperature and will be adverse to the uniformity of performance of the entire cross section; if the cooling temperature is lower than 220° C., a large quantity of martensite will be formed, and can't be eliminated even through the follow-up tempering treatment; consequently, the toughness and plasticity of the steel rail will be severely compromised, or even the steel rail can't be used.
  • the steel rail is loaded into a heating furnace and tempered at 300-350° C. for 4-6 h, and then is cooled to the room temperature by air cooling.
  • the reason for the above setting is: if the tempering temperature is lower than 300° C., the toughness and plasticity of the steel, especially the impact toughness at a low temperature, will be severely degraded, consequently, the high toughness property of bainitic steel rail at a low temperature can't be utilized; in addition, since the carbides can't precipitate sufficiently from the steel, the wear resistance property of the steel rail can't be improved; if the tempering temperature is higher than 350° C., though the toughness and plasticity still increase, the strength and hardness will decrease, consequently, it will be difficult to obtain a steel rail with outstanding overall properties.
  • the reason why the tempering time is set to 4-6 h is: when the tempering time is shorter than 4 h, the carbides in the steel, in particular the carbides in the deep zone of the rail head, can't precipitate sufficiently; when the tempering time is longer than 6 h, the excessively long processing time will bring little benefit, because the carbide precipitation in the steel has already completed and the objective of the tempering process has already attained.
  • the steel rail is taken out and cooled to the room temperature by air cooling, so as to obtain a finished steel rail product.
  • the steel rail contains: 0.15 wt %-0.30 wt % C, 1.00 wt %-1.80 wt % Si, 1.50 wt %-2.50 wt % Mn, 0.50 wt %-1.00 wt % Cr, 0.20 wt %-0.50 wt % Mo, and Fe that accounts for the remaining content, and the total weight percentage of Mn and Cr meets 2.2% ⁇ Mn+Cr ⁇ 3.0%.
  • examples 1-6 and Comparative Examples 1-6 the following steel rails 1-6 are used respectively.
  • the chemical compositions of the steel rails are shown in Table 1.
  • Example 2-6 Prepare steel rails in examples 2-6 with the method described in Example 1, but replace the control parameters in the operating process in Example 1 with those shown in Table 2.
  • the steel rails prepared with the method in Examples 2-6 are denoted as A2-A6.
  • the processing method is a conventional thermal processing method and the specific control parameters in the operating process are shown in Table 2.
  • the steel rails prepared with the method in Comparative Examples 1-6 are denoted as D1-D6.
  • the tensile property of the steel rail is measured according to GB/T228-2010 “Tensile Testing Method of Metallic Materials at Room Temperature”, and the measured Rp0.2 (stress at 0.2% of non-proportional elongation), Rm (tensile strength), A % (elongation), Z % (reduction of cross section) are shown in Table 3;
  • Wearing tests are carried out on a MM-200 wear testing machine to test the average weight loss resulted from wearing.
  • the samples are taken from the rail head part of steel rails A1-A6 and D1-D6. In all of the wearing tests, the lower grinding samples are made of the same material.
  • the measured values of average weight loss resulted from wearing are shown in Table 3.
  • the testing parameters are as follows:
  • the carbide length, the included angle between the carbides and the bainitic ferrite, and the percentage of the carbides are measured with the following method:
  • Samples are taken from the steel rails prepared in the Examples and Comparative Examples and film samples in thickness of ⁇ 50 ⁇ m are obtained from the samples. Then, the samples are processed by two-jet electropolishing for thickness reduction; next, the carbide morphology is indexed and observed under a transmission electron microscope (TEM), and the included angle between the carbides and the bainitic ferrite is measured; carbides in 0.05-0.5 ⁇ m length and oriented to a direction at a 50-70° included angle are selected, and the carbide area and percentage are measured by approximate estimation.
  • TEM transmission electron microscope
  • the morphology of the carbides varies in different viewing fields, in order to ensure the accuracy of measurement, at least 20 viewing fields on a steel rail with same material, same process and same sampling position are observed, and the average value is taken, and the percentage of carbides that meet the requirement is determined.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
US14/702,188 2014-05-08 2015-05-01 Bainitic steel rail containing trace amounts of carbides and producing method of the same Abandoned US20150322553A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN201410192490.XA CN103966520B (zh) 2014-05-08 2014-05-08 一种含有微量碳化物的贝氏体钢轨及其生产方法
CN201410192490.X 2014-05-08

Publications (1)

Publication Number Publication Date
US20150322553A1 true US20150322553A1 (en) 2015-11-12

Family

ID=51236516

Family Applications (1)

Application Number Title Priority Date Filing Date
US14/702,188 Abandoned US20150322553A1 (en) 2014-05-08 2015-05-01 Bainitic steel rail containing trace amounts of carbides and producing method of the same

Country Status (3)

Country Link
US (1) US20150322553A1 (fr)
CN (1) CN103966520B (fr)
FR (1) FR3020816B1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018109556A (ja) * 2017-01-04 2018-07-12 公益財団法人鉄道総合技術研究所 ベイナイトレール白色層厚さ推定方法
EP3500688A4 (fr) * 2016-06-27 2020-11-11 Arcelormittal Poland S.A. Acier multiphasique, en particulier pour la fabrication de rails de voie normale
US11566307B2 (en) 2018-03-30 2023-01-31 Jfe Steel Corporation Rail

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103993237B (zh) * 2014-05-22 2016-07-06 攀钢集团攀枝花钢铁研究院有限公司 一种耐磨损的贝氏体道岔轨及其生产方法
CN106435367B (zh) * 2016-11-23 2018-07-10 攀钢集团攀枝花钢铁研究院有限公司 一种贝氏体钢轨及其制备方法
CN110541125B (zh) * 2019-09-12 2022-11-25 北京交通大学 一种重载铁路用高耐磨贝氏体复相组织钢轨及其制造方法
CN110885950A (zh) * 2019-10-30 2020-03-17 鞍钢股份有限公司 一种高强韧性起重机用钢轨及其制造方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5759299A (en) * 1994-05-10 1998-06-02 Nkk Corporation Rail having excellent resistance to rolling fatigue damage and rail having excellent toughness and wear resistance and method of manufacturing the same

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH05271875A (ja) * 1992-03-30 1993-10-19 Nippon Steel Corp 耐摩耗性熱間圧延用ロール材質
CN1086743C (zh) * 1998-01-14 2002-06-26 新日本制铁株式会社 具有高抗表面疲劳损伤性和高耐磨性的贝氏体钢钢轨
JP2007197776A (ja) * 2006-01-27 2007-08-09 Jfe Steel Kk 耐遅れ破壊特性と耐疲労き裂伝播特性に優れた高強度鋼材およびその製造方法
CN102839268B (zh) * 2012-08-28 2014-08-13 攀钢集团攀枝花钢铁研究院有限公司 一种贝氏体道岔钢轨的热处理方法
CN102899471B (zh) * 2012-10-17 2014-08-06 攀钢集团攀枝花钢铁研究院有限公司 贝氏体钢轨的热处理方法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5759299A (en) * 1994-05-10 1998-06-02 Nkk Corporation Rail having excellent resistance to rolling fatigue damage and rail having excellent toughness and wear resistance and method of manufacturing the same

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
NPL-1: Jung et al, Bainite transformation in a silicon steel, ISIJ international, Vol.37(1997), No.8, pp.789-796, *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3500688A4 (fr) * 2016-06-27 2020-11-11 Arcelormittal Poland S.A. Acier multiphasique, en particulier pour la fabrication de rails de voie normale
JP2018109556A (ja) * 2017-01-04 2018-07-12 公益財団法人鉄道総合技術研究所 ベイナイトレール白色層厚さ推定方法
US11566307B2 (en) 2018-03-30 2023-01-31 Jfe Steel Corporation Rail

Also Published As

Publication number Publication date
CN103966520B (zh) 2016-07-06
FR3020816B1 (fr) 2017-03-03
FR3020816A1 (fr) 2015-11-13
CN103966520A (zh) 2014-08-06

Similar Documents

Publication Publication Date Title
US20150322553A1 (en) Bainitic steel rail containing trace amounts of carbides and producing method of the same
US20190338402A1 (en) Method for manufacturing railway vehicle wheel
AU2015204356B2 (en) High-strength bainitic steel rail and producing method thereof
US10214799B2 (en) Heat treatment method for increasing the depth of hardening layer in a steel rail and steel rail obtained with the method
JP6765495B2 (ja) 高強度、高靭性、耐ヒートクラック性鉄道輸送用ベイナイト鋼車輪及びその製造方法
JP6765496B2 (ja) 高靭性鉄道輸送用ベイナイト鋼車輪及びその製造方法
CN103014296B (zh) 车轴钢的热处理工艺
WO2018010494A1 (fr) Rail en acier hyper-eutectoïde et procédé de fabrication associé
Hernández et al. Properties and microstructure of high performance wheels
CN105239015A (zh) 一种高碳中锰耐磨钢及热轧板制造方法
CN105154773B (zh) 一种重载铁路用钢轨及其生产方法和应用
CN103014535B (zh) 车轴钢及车轴
CN106521343A (zh) 一种超高强度铝合金化超高碳车轮用钢及其热处理方法
CN106435367A (zh) 一种贝氏体钢轨及其制备方法
JPWO2020067520A1 (ja) 鉄道車輪
CN105063490B (zh) 一种高速铁路用钢轨及其生产方法和应用
JP6455128B2 (ja) パーライトレール及びその製造方法
JP6056647B2 (ja) 軸受鋼の製造方法およびその製造方法で得られる軸受鋼
BR102019014230B1 (pt) Parte de via e método para produzir uma parte de via
Zhang et al. Microstructure and properties of carbide free bainite railway wheels produced by programmed quenching
WO2018174094A1 (fr) Procédé de fabrication de rail
US20150368765A1 (en) Nano-Pearlite Rail and Process for Manufacturing Same
JP2008025002A (ja) 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
CN112813348A (zh) 一种空冷马氏体和残余奥氏体复相中锰钢轨钢及制备方法
CN105040532B (zh) 一种重载铁路用钢轨及其生产方法和应用

Legal Events

Date Code Title Description
AS Assignment

Owner name: PANGANG GROUP PANZHIHUA IRON & STEEL RESEARCH INST

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:HAN, ZHENYU;ZOU, MING;JIA, JIHAI;AND OTHERS;REEL/FRAME:036517/0461

Effective date: 20150428

STCB Information on status: application discontinuation

Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION