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Clean isothermal quenching or stepwise quenching process

A technology of isothermal quenching and graded quenching, applied in the field of warm quenching or graded quenching and quenching, can solve the problems of high cost, increased production cost and difficult maintenance.

Inactive Publication Date: 2003-02-26
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

But there are also deficiencies, that is, it is necessary to configure a quenching salt tank and an isothermal nitrate tank. The vapor of the molten nitrate in the salt tank and the residual salt of the nitrate will cause environmental pollution, and the isothermal salt tank has a total of 31 trays , bulky, in which the elevator, rotary transfer machine and agitator all need to work in molten salt, the cost is expensive, and the maintenance is difficult. After austempering in the salt bath, post-cleaning must be carried out, which increases the production cost

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0010] Example 1: For ball bearing parts (inner and outer rings) with an effective thickness < 20 mm.

[0011] After austenitizing, it is quenched into a quenching tank equipped with a mesh belt that continuously moves and lifts the workpiece to discharge liquid (water), so that the surface of the workpiece is cooled to 170-240°C to discharge liquid. The residence time in the quenching tank can be determined by pre-test, and by adjusting the transmission speed of the mesh belt, the time the workpiece stays in the quenching tank can be controlled, so as to control the outlet temperature. Immediately after the workpiece comes out of the liquid, it is sent to the air medium with a temperature of 170-240 ° C for isothermal residence (the isothermal temperature and residence time are determined according to the requirements of the workpiece and the steel part, which is the same as ordinary austempering in principle. For example, the wall thickness is 20mm. The isothermal temperatur...

Embodiment 2

[0012] Example 2: 40Cr size 18.5×30×50mm

[0013] The austenitizing temperature is 860°C. After the furnace temperature reaches the temperature, keep it warm for 15', cool it to 170°C with brine, and turn to the graded residence stage after about 5 seconds. At this stage, the surface temperature of the workpiece is kept at 170°C by spray cooling method. The fractional residence time was approximately 9 minutes, followed by air cooling to room temperature. Hardness 48-52HRC, distortion ≤ 0.05mm.

Embodiment 3

[0014] Example 3: 3Cr 2 NiMnMo alloy steel, size 1700×000×460 modules

[0015] After being austenitized at 860°C, it is properly pre-cooled and then quenched into water or water-soluble medium for cooling, which is similar to ordinary quenching, but it is different from ordinary quenching in that ordinary quenching is to cool the workpiece to room temperature, while the present invention is to When the workpiece is cooled to 150-180°C, the workpiece is lifted out of the water tank (or water-soluble medium tank), and sprayed or air-jet or air-cooled. By adjusting the water pressure, water volume or wind pressure, and air volume, the surface temperature of the workpiece remains unchanged. Realize austempering or graded quenching. On the air supply pipeline and water supply pipeline of the spray-jet-air-cooling device, an electric control valve is installed to measure the surface temperature of the workpiece, and the sampling value input valve position of the thermometer is adju...

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Abstract

The present invention relates to belongs to the field of thermal technological process, and is a clean isothermal quenching or stepwise quenching process which includes heating workpiece to austenite state, selecting quenching cooling medium according to workpiece size and steel hardness penetration, turning to isothermal quenching or stepwise quenching stage while the surface of the workpiece is cooled to proper temperature, regulating spraying and air cooling rate to control the surface temperature so as to make the heat taken from the surface equal to that transferred from inside the workpiece to the surface and make the surface temperature in that specifiec by the isothermal quenching or stepwise quenching specification.

Description

technical field [0001] The invention relates to a quenching method, in particular to a clean austempering or graded quenching method, which belongs to the technical field of heat treatment technology. Background technique [0002] Whether it is isothermal quenching or graded quenching, a bath is required. The bath can be a hot oil bath or a nitrate salt bath, but no matter what kind of bath, there is an environmental pollution problem, and there is a danger of explosion when the nitrate salt is overheated. Oil baths are also a fire hazard. After literature search, it was found that Fei Mingjie wrote an article "Application of Bainite Austempering Production Line on Bearing Rings" in "Metal Heat Treatment" 2001, No.10, P30-32. The complete production line jointly manufactured by Beijing Aichelin is used for bainite austempering of bearing rings. This technology uses bainite austempering for bearing rings. The strength, fracture toughness, contact fatigue life and heat treatm...

Claims

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Application Information

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IPC IPC(8): C21D1/20
Inventor 胡明娟潘健生宋冬利姚新
Owner SHANGHAI JIAO TONG UNIV
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