A method for controlling deformation of large-size medium-low carbon alloy steel square pieces during heat treatment

By employing methods such as suspended hanging of a pit-type heating furnace, limited-rate heating, weak cooling, and residual heat correction, the problems of deformation and uneven cooling of large-sized medium and low carbon alloy steel square parts during heat treatment were solved, achieving low-cost and high-quality heat treatment results.

CN122128494APending Publication Date: 2026-06-02HENAN ZHONGYUAN SPECIAL STEEL EQUIP MFG CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
HENAN ZHONGYUAN SPECIAL STEEL EQUIP MFG CO LTD
Filing Date
2026-03-17
Publication Date
2026-06-02

AI Technical Summary

Technical Problem

Large-sized square parts made of medium and low carbon alloy steel suffer from severe deformation and uneven quenching and cooling during heat treatment, resulting in the inability to perform precision machining and uneven mechanical properties across the entire cross section. Existing methods that increase machining allowance or cooling intensity lead to high costs, deformation, and cracking.

Method used

The well-type heating furnace is suspended vertically, with limited heating rate and stepped heat preservation. It is quenched with a weak cooling medium, and the microstructure is stabilized by high-temperature tempering. Deformation is reduced and surface quality is protected by residual heat correction and slow pressure correction.

Benefits of technology

It effectively reduces deformation during heat treatment, reduces machining allowance, lowers production costs, ensures uniform mechanical properties across the entire cross section, and improves surface quality.

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Abstract

This invention relates to a method for controlling deformation during heat treatment of large-sized medium-low carbon alloy steel square parts. The method employs a pit-type heating furnace with suspended hanging to ensure verticality and prevent deformation caused by uneven placement during heating. A limited-rate heating and stepped heat preservation method is used to reduce the temperature difference between the inside and outside of the workpiece, thereby reducing internal thermal stress and minimizing the risk of deformation or cracking. While ensuring quenching effect, a water-soluble medium with a low cooling rate (6.0%~12%) is used for quenching cooling to reduce deformation caused by structural transformation stress. High-temperature tempering is used to stabilize the microstructure and obtain the desired comprehensive properties. After tempering, limited-rate furnace cooling is performed to remove residual stress within the workpiece. The residual heat of the workpiece after tempering is used for thermal correction, reducing correction stress. Vertical correction with overlapping edges, protection with thin iron or copper sheets, and pressure-relieving correction methods prevent damage to the surface and edges of the square parts, improving surface quality and reducing deformation problems in large-sized medium-low carbon alloy steel square parts during heat treatment.
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