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Thermal treatment process for low-alloy steel castings

A low-alloy steel and casting technology, applied in the field of heat treatment process of low-alloy steel castings, can solve the problems of easy to produce temper brittleness, poor toughness of low-alloy steel castings, environmental pollution, etc., to reduce environmental pollution and safety hazards, meet the Strength and hardness requirements, the effect of reducing production costs

Inactive Publication Date: 2016-07-20
QINGDAO QINDE RIGGING HARDWARE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the heat treatment process of low-alloy steel castings generally adopts normalizing-quenching-tempering, in which quenching medium uses quenching oil, and its ratio is 1:10 by weight, that is, 1 ton of castings is put into 10 tons of quenching oil to ensure the quenching effect After the quenching oil has been used for a period of time, the oxidized powder of the casting and the carbonization of the medium oil will increase the viscosity of the quenching oil and reduce the oil volume, and new quenching oil must be added, resulting in high oil quenching costs; Fire will bring potential safety hazards, and a large amount of harmful substances will be produced during quenching, causing pollution to the environment
The tempering temperature of conventional low-alloy steel is 550-560°C, and the cooling method is to cool out of the furnace when the temperature is lower than 200°C. The low-alloy steel castings treated by the above heat treatment process have poor toughness, and the bending angle is lower than 80°, which cannot meet the requirements. The demand for high toughness, and the above cooling method, when the casting temperature is in the range of 200-400 ℃, it is easy to produce temper brittleness, which will reduce the mechanical properties of the casting

Method used

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  • Thermal treatment process for low-alloy steel castings

Examples

Experimental program
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Effect test

Embodiment 1

[0017] Embodiment 1: The heat treatment process steps of the low-alloy steel casting of the present embodiment are as follows:

[0018] (1) Normalizing: Place the low-alloy steel casting in a normalizing furnace, raise the temperature to 870°C, keep it warm for 3 hours, and cool it to room temperature after taking it out of the furnace;

[0019] (2) Quenching: Place the low-alloy steel casting in a quenching furnace, raise the temperature to 850°C, keep it warm for 2.5 hours, and cool it to room temperature when it comes out of the furnace;

[0020] (3) Tempering: Place the low-alloy steel casting in a tempering furnace, raise the temperature to 700°C, keep it warm for 3 hours, and then take it out of the furnace and air-cool it to room temperature.

Embodiment 2

[0021] Embodiment 2: the heat treatment process steps of the low-alloy steel casting of the present embodiment are as follows:

[0022] (1) Normalizing: Place the low-alloy steel casting in a normalizing furnace, raise the temperature to 880°C, keep it warm for 2.5 hours, and cool it to room temperature after taking it out of the furnace;

[0023] (2) Quenching: Place the low-alloy steel casting in a quenching furnace, raise the temperature to 860°C, keep it warm for 3 hours, and cool it to room temperature when it comes out of the furnace;

[0024] (3) Tempering: Place the low-alloy steel casting in a tempering furnace, raise the temperature to 710°C, keep it warm for 3 hours, and then take it out of the furnace and air-cool it to room temperature.

Embodiment 3

[0025] Embodiment 3: the heat treatment process steps of the low-alloy steel casting of the present embodiment are as follows:

[0026] (1) Normalizing: Place the low-alloy steel casting in a normalizing furnace, raise the temperature to 890°C, keep it warm for 3 hours, and cool it to room temperature after taking it out of the furnace;

[0027] (2) Quenching: Place the low-alloy steel casting in a quenching furnace, raise the temperature to 870°C, keep it warm for 3 hours, and cool it to room temperature after taking it out of the furnace;

[0028] (3) Tempering: Place the low-alloy steel casting in a tempering furnace, raise the temperature to 710°C, keep it warm for 2.5 hours, and then take it out of the furnace and air-cool it to room temperature.

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Abstract

The invention relates to a thermal treatment process for castings, in particular to a thermal treatment process for low-alloy steel castings. The thermal treatment process includes the following steps of normalizing, water quenching and high-temperature tempering and air cooling. By the adoption of the thermal treatment process for the low-alloy steel castings, the tempering temperature of the low-alloy steel castings is increased, the direct tapping air cooling manner is adopted, the treated low-alloy steel castings can meet the requirements for the strength and hardness, and meanwhile the toughness of the castings is improved; and in the thermal treatment process for the low-alloy steel castings, the water cooling manner is used in the quenching step, production cost is reduced, environmental contamination is reduced, and potential safety hazards are reduced.

Description

technical field [0001] The invention relates to a heat treatment process for castings, in particular to a heat treatment process for low alloy steel castings. Background technique [0002] Due to the advantages of high strength and high wear resistance, low-alloy steel castings gradually replace ordinary carbon steel and are widely used in the field of casting, especially ZG42CrMo, ZG35CrMo and other materials, whose strength is 2-3 times that of ordinary carbon steel. In practical application, the strength, hardness and toughness of low alloy steel need to be selected reasonably. At present, the heat treatment process of low-alloy steel castings generally adopts normalizing-quenching-tempering, in which quenching medium uses quenching oil, and its ratio is 1:10 by weight, that is, 1 ton of castings is put into 10 tons of quenching oil to ensure the quenching effect After the quenching oil has been used for a period of time, the oxidized powder of the casting and the carbon...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/22C21D6/00
Inventor 范勤德
Owner QINGDAO QINDE RIGGING HARDWARE
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