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Method for graded hardening or isothermal hardening utilizing fluidized bed

A technology of isothermal quenching and graded quenching, which is applied in the field of warm quenching, can solve problems such as environmental pollution, and achieve the effects of overcoming environmental pollution, expanding the scope of application, and cleaning the environment

Inactive Publication Date: 2003-10-22
SHANGHAI JIAO TONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The present invention aims at the deficiencies and defects in the background technology, and provides a method for applying a fluidized bed to carry out classification or isothermal quenching, so that it can completely overcome the above-mentioned disadvantages of using a nitrate bath or hot oil as a classification or isothermal bath, and the existing The technology is only suitable for workpieces with small cross-sectional dimensions and causes environmental pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] Embodiment 1: The silicon steel sheet cold-stamping die has matching requirements with the punch, the thickness is 20 mm, and it is made of GCr15 steel. The workpiece is austenitized and quenched into quenching oil or water-soluble medium at 840°C, and stays for 20 seconds to cool the surface of the workpiece to about 240°C. After taking it out, it immediately enters the fluidized bed at 240°C for isothermal cooling for 4 hours. Then remove and air cool to room temperature. The hardness of the workpiece is 60-63HRC, the plane deformation of the die is ≤0.05mm, and the shrinkage of the inner hole meets the requirements.

Embodiment 2

[0015] Embodiment 2: an eccentric shaft made of 12CrNi3 carburizing steel, with a thickness of 15 mm, an outer diameter of Φ50, an inner diameter of Φ20, and an eccentricity of 5 mm. Carburizing is carried out in a continuous segmental controllable mesh belt furnace, the carbon potential is controlled at 0.75-0.8%, and the carburizing time is controlled by the moving speed of the mesh belt. The workpiece is quenched into rapid quenching oil or water-soluble medium or water-soluble medium with a cooling rate close to oil at the quenching port, and the cooling time is controlled. The workpiece is lifted out by the rapid lifting device in time, and enters the fluidized bed at 230 °C for isothermal cooling for 4 hours, and then Remove and cool in oil to room temperature. The hardness of the workpiece is 58-62HRC, the grade of carbide is within the technical range, and the deformation is ≤0.05mm.

[0016] Determine the residence time of the workpiece in the cooling medium, and mea...

Embodiment 3

[0017] Example 3: The bearing ring is made of GCr15, the wall thickness is 18mm, the hardness of the infiltrated layer is required to be 60-63HRC, the hardness unevenness of the same part is ≤1HRC, and the swelling amount is ≤0.10mm. After austenitizing, the ferrule is quenched into UCON water-soluble quenching medium, cooled for 18 seconds (calculated based on the effective thickness of 1 second / mm), and immediately transferred to a fluidized bed at a temperature of 230 ° C for 4 hours, taken out air cooled. The hardness of the treated bearing ring is 62-63HRC, and the radial expansion is in the range of 0.03-0.05mm, all of which meet the technical requirements.

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PUM

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Abstract

The method for making progressive or isothermal quenching by using fluidized bed includes the following steps: heating workpiece to austenite state or austenite + carbide state, selecting cooling medium to make quenching operation, when the surface temp. of the workpiece is reduced to supercooling austenite stable zone or reduced to the temp. nearby Ms point of steel, promptly feeding the workpiece into fluidized bed to make progressive or isothermal quenching, at the moment, making fluidized bed be retained at some temp. nearby Ms point of said steel, when the temp. on the section of the workpiece is more uniform, taking out workpiece and cooling to room temp. to obtain the structure in which the martensite is used as main component, and when the isothermal quenching is made.

Description

technical field [0001] The invention relates to a method for grading or austempering steel parts, in particular to a method for grading or austempering using a fluidized bed, which belongs to the technical field of metal heat treatment. Background technique [0002] The quenching operation of staged quenching and austempering can reduce the deformation and cracking of the workpiece, which has been paid attention to by people. However, these two methods require the use of a heat bath kept at a certain temperature near the Ms point as the intermediate cooling medium. This medium Nitrate baths or hot oil are often used. The nitrate salt bath or hot oil causes environmental pollution, and its use should be restricted; in addition, the corresponding cooling rate of the nitrate salt bath or hot oil is relatively low, which is only suitable for steel types with high hardenability, and for low hardenability steels. Alloy steel or carbon steel, graded quenching or austempering are o...

Claims

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Application Information

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IPC IPC(8): C21D1/19C21D1/62
Inventor 潘健生胡明娟张伟民朱祖昌
Owner SHANGHAI JIAO TONG UNIV
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