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Post-forging heat treatment process for 45Cr4NiMoV alloy steel large back-up rolls of rolling mills

A technology of alloy steel and backup roll, applied in the field of heat treatment of large forgings, can solve the problems of slow cooling of the core, insufficient austenite transformation, insufficient grain refinement of the backup roll, etc.

Inactive Publication Date: 2012-04-18
洛阳中创重型机械有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0019] (1) Putting into the furnace after forging is usually kept at 600-650°C and then heated up directly, so that the cooling of the core is very slow, and the austenite transformation is not sufficient
[0020] (2) After forging, a heat treatment method of normalizing (normalizing + spheroidizing annealing + tempering) is adopted, which is not sufficient for refining the grain of the backup roll

Method used

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Embodiment

[0047] The large backup roll refers to a backup roll with a roll body diameter greater than or equal to φ1500mm.

[0048] The embodiments of the present invention are given to illustrate the present invention, but do not constitute any limitation to the present invention.

[0049] The manufacturing process of the large back-up roll: material preparation—rough smeltingladle refining—vacuum ingot casting—forging—post-forging heat treatment (high temperature normalizing + low temperature normalizing + spheroidizing annealing + high temperature tempering, Air cooling)—rough machining—ultrasonic flaw detection—preparatory heat treatment (quenching + high temperature tempering)—semi-finishing—ultrasonic flaw detection—packaging.

example

[0050] Example: 45Cr4NiMoV alloy steel large backup roll post-forging heat treatment process

[0051] The specifications of the support roller are: the diameter of the roller body is φ1750

[0052] The heat treatment process for large backup rolls of 45Cr4NiMoV alloy steel in rolling mills includes post-forging heat treatment process, preliminary heat treatment, and final heat treatment. The post-forging heat treatment process is as follows:

[0053] (1) After forging, air-cool to 400-450°C and enter the furnace, and the temperature of the heat treatment furnace is not lower than 600°C; it is beneficial to shorten the holding time and quickly transform the austenite in the core of the blank into a pearlite structure. Fast heating speed re-austenitization for recrystallization and refinement, followed by air cooling for normalizing;

[0054] (2) High temperature normalizing + low temperature normalizing + spheroidizing annealing + high temperature tempering process, air c...

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Abstract

The invention belongs to the technical field of large forging heat treatment processes, and mainly relates to a post-forging heat treatment process for 45Cr4NiMoV alloy steel large back-up rolls of rolling mills. A forged back-up roll is cooled to 400 DEG C to 500 DEG C by the air and put into a furnace, and the material temperature in the heat treatment furnace is not lower than 600 DEG C; a high-temperature normalizing plus low-temperature normalizing plus spheroidizing annealing plus high-temperature tempering process is adopted, and air cooling is carried out. The adopted post-forging heat treatment process disclosed by the invention is characterized in that: crystalline grains are thinned; the structure is regulated, so that the network structure is removed; the carbon segregation ofthe upper part of the large steel ingot is considerable, temperature higher than Ac1 is kept for a long time, consequently, part of carbide is remelted, the remaining unmelted carbide is spheroidized, and a granular pearlite structure is obtained during cooling; consequently, the structure toughness is high, and structure preparation is done for the next step of heat treatment; and fish eyes are prevented.

Description

[0001] technical field [0002] The invention belongs to the technical field of heat treatment process for large forgings, and mainly relates to a post-forging heat treatment process for large backing rolls of 45Cr4NiMoV alloy steel in rolling mills. Background technique [0003] Large back-up rolls are generally used in the key and core parts of large-scale strip rolling equipment. They are important parts used to support work rolls or intermediate rolls in rolling mills to prevent deflection and deformation of work rolls during rolling and affect the quality of the plate. , is the basic part of large-scale cold rolling and hot rolling equipment. [0004] With the development of rolling mills in the direction of automation, high precision, and high-quality shape control, rolling conditions are becoming more and more stringent. Improving rolling efficiency, reducing rolling costs, and ensuring product quality have become prominent issues. [0005] Due to the long-term heavy...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/38C21D11/00
Inventor 平志革雷静波雷静桃朱坚民
Owner 洛阳中创重型机械有限公司
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