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Steel for frog point rail and heat treatment method thereof

A heat treatment method and frog technology, which are applied in the field of frog core rail steel manufacturing, can solve problems such as unfavorable energy saving and cost saving, unfavorable production scheduling, high price of rare earth, etc., so as to reduce the processing allowance and make it easy to obtain materials. , the effect of low cost

Pending Publication Date: 2021-10-29
CHINA RAILWAY BAOJI BRIDGE GRP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The shortcomings of the above-mentioned background technology: In CN102899471B patent, cooling and tempering need to be continued, which is not conducive to production scheduling
The heat treatment process in the CN105385938B patent includes: normalizing + adjustment treatment, quenching + isothermal phase transformation, tempering and tempering treatment. There are many process steps and each process lasts at least 5 hours, which is not conducive to saving energy and cost
The chemical composition of CN109023096A patent contains Nb and La, Y, Ce rare earth elements, and rare earths are expensive

Method used

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  • Steel for frog point rail and heat treatment method thereof
  • Steel for frog point rail and heat treatment method thereof
  • Steel for frog point rail and heat treatment method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] Embodiment 1: with reference to attached figure 1 . A steel for frog core rail, C: 0.24%, Si: 1.86%, Mn: 1.85%, P: 0.020%, S: 0.007%, Cr: 1.32%, Ni: 0.31%, Mo: 0.31%, V : 0.11%, Al: 0.12%, the balance is Fe and unavoidable impurities.

[0027] The heating temperature of the first stage of normalizing is 680°C, heat preservation for 1h, quenching heating temperature: 900°C, heat preservation for 250min, cooling rate: 25°C / min, cool to room temperature at 2°C / min after cooling to 335°C; tempering temperature 280°C, heat preservation 3h, take out of the oven and cool to room temperature at 8°C / min.

[0028] Mechanical properties: the yield strength is 1080MPa, the tensile strength is 1321MPa, the section hardness is 39-44HRc, the surface hardness is 388-399HB, the elongation is 19%, the section shrinkage is 42%, and the impact energy at room temperature (20°C) is 99 / 97 / 92J , Low temperature (-40°C) impact energy 35 / 45 / 48J, microstructure is granular bainite + retained ...

Embodiment 2

[0029] Embodiment 2: with reference to attached figure 2 . A steel for frog core rail, C: 0.28%, Si: 1.92%, Mn: 2.00%, P: 0.010%, S: 0.005%, Cr: 1.44%, Ni: 0.26%, Mo: 0.34%, V : 0.14%, Al: 0.15%, the balance is Fe and unavoidable impurities.

[0030] The heating temperature of the first stage of normalizing is 685°C, heat preservation for 1h, quenching heating temperature: 860°C, heat preservation for 360min, cooling rate: 28°C / min, cool to 398°C and then air cool to room temperature; tempering temperature 240°C, hold for 5h, and air cool to room temperature.

[0031]Mechanical properties: the yield strength is 1056MPa, the tensile strength is 1344MPa, the section hardness is 38-43HRc, the surface hardness is 395-413HB, the elongation is 14%, the section shrinkage is 58%, and the impact energy at room temperature (20°C) is 77 / 86 / 92J , Low temperature (-40°C) impact energy 40 / 52 / 60J, microstructure is granular bainite + retained austenite.

Embodiment 3

[0032] Embodiment 3: with reference to attached image 3 . A steel for frog core rail, C: 0.30%, Si: 1.88%, Mn: 1.90%, P: 0.020%, S: 0.004%, Cr: 1.37%, Ni: 0.33%, Mo: 0.28%, V : 0.07%, Al: 0.06%, the balance is Fe and unavoidable impurities.

[0033] The heating temperature of the first stage of normalizing is 675°C, heat preservation for 1h, quenching heating temperature: 950°C, heat preservation for 90min, cooling rate: 15°C / min, cool to room temperature at 4°C / min after cooling to 250°C; tempering temperature 325°C, heat preservation 4h, out of the oven and cooled to room temperature at 16°C / min.

[0034] Mechanical properties: the yield strength is 1120MPa, the tensile strength is 1387MPa, the section hardness is 38-42HRc, the surface hardness is 404-425HB, the elongation is 12%, the section shrinkage is 47%, and the impact energy at room temperature (20°C) is 95 / 72 / 78J , Low temperature (-40°C) impact energy 53 / 50 / 49J, microstructure is granular bainite + retained aust...

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Abstract

The invention relates to steel for a frog point rail and a heat treatment method thereof. The steel is low in cost, low in tempering temperature, short in time, low in energy consumption and small in thermal stress and structural stress during heat treatment heating and cooling, and unilateral deformation of the frog point rail is smaller than 1.5 mm when the frog point rail is horizontally placed in a common box-type furnace for heat treatment. The steel comprises the following alloy components of, in percentage by mass, 0.22%-0.31% of C, 1.86%-2.04% of Si, 1.81%-2.00% of Mn, less than or equal to 0.025% of P, less than or equal to 0.010% of S, 1.32%-1.45% of Cr, 0.26%-0.33% of Ni, 0.28%-0.34% of Mo, 0.07%-0.14% of V and 0.01%-0.15% of Al, and the balance Fe and inevitable impurities. The method has the advantages that firstly, the heat treatment process is simple; secondly, rare earth elements are not contained, materials are easy to obtain, and cost is low; thirdly, the tempering temperature is low, the time is short, and the energy consumption is low; fourthly, the material has excellent combination of strength, plasticity and toughness; and fifthly, the thermal stress and the structural stress during heat treatment and cooling are small, the unilateral deformation of the frog point rail can be smaller than 1.5 mm when the frog point rail is horizontally placed in the common box-type furnace for heat treatment, then the machining allowance of a rough blank can be reduced, and the machining amount is reduced.

Description

technical field [0001] The present invention relates to a kind of low cost, low tempering temperature, short time, less energy consumption, small thermal stress and structural stress during heat treatment heating and cooling, and one-side heat treatment when the frog core rail is placed flat in a common box furnace. The invention relates to steel for frog core rails with deformation less than 1.5 mm and a heat treatment method thereof, belonging to the field of steel for frog core rails. Background technique [0002] CN102899471B, "Heat treatment method for bainite rail", the heat treatment method for the bainite rail includes: naturally cooling the rail after finishing rolling, so that the surface temperature of the rail head is reduced to 460-490°C; cooling the rail at 2.0- The cooling rate of 4.0℃ / s is forced to cool, so that the surface temperature of the rail head drops to 250-290℃; the temperature of the rail rises naturally until the surface temperature of the rail he...

Claims

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Application Information

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IPC IPC(8): C22C38/02C22C38/04C22C38/06C22C38/44C22C38/46C22C38/58C21D6/00C21D1/28
CPCC22C38/02C22C38/04C22C38/44C22C38/46C22C38/06C22C38/58C21D6/004C21D6/005C21D6/008C21D1/28
Inventor 任伟伟高尚君王磊付涛郑会锋
Owner CHINA RAILWAY BAOJI BRIDGE GRP