Preheat treatment process for super-strong high-toughness carburizing steel bar and forge piece

A technology for preparatory heat treatment and carburizing steel, applied in the field of material processing, can solve the problems that cannot be completely eliminated, weakened tissue inheritance, reduced α phase supersaturation and hardness, etc.

Pending Publication Date: 2022-04-12
AVIC BEIJING INST OF AERONAUTICAL MATERIALS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It can be seen that although high temperature tempering reduces the supersaturation and hardness of the α phase and weakens the tissue inheritance, it cannot completely eliminate

Method used

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  • Preheat treatment process for super-strong high-toughness carburizing steel bar and forge piece
  • Preheat treatment process for super-strong high-toughness carburizing steel bar and forge piece
  • Preheat treatment process for super-strong high-toughness carburizing steel bar and forge piece

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] 1. Processing object: super-strong and high-toughness carburizing steel forged bar with a diameter of 160mm

[0034] 2. Preparatory heat treatment process

[0035] (1) Primary high-temperature tempering: the bar is heated up with the furnace, heated to 680°C, held for 20 hours, cooled to 300°C in the furnace, and then air-cooled to room temperature.

[0036] (2) Incomplete annealing: The bar is heated up with the furnace, heated to 950°C, held for 3 hours, cooled to 500°C in the furnace, and air-cooled to room temperature.

[0037] (3) Secondary high-temperature tempering: the bar is heated up with the furnace, heated to 680°C, held for 20 hours, cooled to 300°C in the furnace, and then air-cooled to room temperature.

[0038] 3. Microstructure and hardness

[0039] Rod microstructure see figure 1 , is a granular carbide dispersed on the tempered sorbite matrix, with a hardness of 31.5HRC.

Embodiment 2

[0041] 1. Processing object: super strong and high toughness carburized steel bevel gear forgings

[0042] 2. Preparatory heat treatment process

[0043] (1) Primary high-temperature tempering: the forging is heated up with the furnace, heated to 700°C, held for 8 hours, cooled to 500°C in the furnace, and air-cooled to room temperature after being released from the furnace.

[0044] (2) Incomplete annealing: the forging is heated up with the furnace, heated to 1000 ° C, holding time for 2 hours, cooled to 500 ° C in the furnace, and air-cooled to room temperature after being released from the furnace.

[0045] (3) Secondary high-temperature tempering: the forging is heated up with the furnace, heated to 700°C, held for 8 hours, cooled to 500°C in the furnace, and air-cooled to room temperature after being released from the furnace.

[0046] 3. Microstructure and hardness

[0047] Forging microstructure see figure 2 , is a granular carbide dispersed on the tempered sorbite...

Embodiment 3

[0049] 1. Processing object: super strong and high toughness carburized steel cylindrical gear forgings

[0050] 2. Preparatory heat treatment process

[0051] (1) Primary high-temperature tempering: the forging is put into the furnace when it reaches temperature, the heating temperature is 670°C, the holding time is 12h, and it is air-cooled to room temperature.

[0052] (2) Incomplete annealing: the forging is heated up with the furnace, heated to 980°C, held for 1.5h, and cooled to room temperature in air.

[0053] (3) Secondary high-temperature tempering: the forging is heated up with the furnace, heated to 670°C, held for 12 hours, and air-cooled to room temperature.

[0054] 3. Microstructure and hardness

[0055] Forging microstructure see image 3 , is a granular carbide dispersed on the tempered sorbite matrix, with a hardness of 32HRC.

[0056] Table 1

[0057]

[0058] Table 2

[0059]

[0060] After the above process, the rods or forgings in the embodim...

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Abstract

The invention belongs to the field of material processing, and relates to a preheat treatment process for a super-strong high-toughness carburizing steel bar and a forge piece, which comprises the following steps of: firstly, carrying out primary high-temperature tempering on the bar and the forge piece which are subjected to thermoplasticity forming at the heating temperature of 670-710 DEG C and the heat preservation time of 8-20 hours, and carrying out furnace cooling or air cooling to room temperature; then incomplete annealing is conducted, the heating temperature ranges from 950 DEG C to 1000 DEG C, the heat preservation time ranges from 1 h to 3 h, and furnace cooling or air cooling is conducted to the room temperature; and finally, secondary high-temperature tempering is conducted, the heating temperature ranges from 670 DEG C to 710 DEG C, the heat preservation time ranges from 8 h to 20 h, and furnace cooling or air cooling is conducted to the room temperature. Through the pre-heat treatment, the structure inheritance caused by high-temperature heating before the super-strong high-toughness carburizing steel bar and the forge piece are subjected to plastic forming is eliminated, fine crystal grains are obtained after final heat treatment, the hardness of the bar or the forge piece is reduced, the residual stress is eliminated, and the cutting machining performance is improved.

Description

technical field [0001] The invention belongs to the field of material processing and relates to a preliminary heat treatment process for super-strength and high-toughness carburizing steel bars and forgings. Background technique [0002] Gears, bearings, transmission shafts and main shafts are the key components of mechanical transmission systems such as aero-engines, helicopters, high-speed trains, heavy-duty vehicles and wind power devices. They serve under heavy loads, high speeds, severe state changes and complex stress conditions. It is required to have high load capacity and good heat resistance and wear resistance, so as to ensure the high reliability and durability of the transmission system. In order to meet the use requirements of heavy-duty gears, bearings, transmission shafts and main shafts, the steel should have excellent ultra-high strength and high toughness, good surface superhardening performance and heat resistance. [0003] Preliminary heat treatment is ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/00C21D1/26C21D6/00C21D9/00C22C38/44C22C38/46C22C38/48C22C38/52
Inventor 贺自强杨平杨长树
Owner AVIC BEIJING INST OF AERONAUTICAL MATERIALS
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