Structural steel two-stage heating hardening and tempering process method

A technology of two-stage heating and process method, which is applied in the field of structural steel quenching and tempering, and can solve the problems of undetected quenching and tempering process of structural steel workpieces

Inactive Publication Date: 2020-01-21
JIANGSU JUYUAN ELECTRICAL
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, in the public information, there is no specific quenching and tempering pr

Method used

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  • Structural steel two-stage heating hardening and tempering process method

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Embodiment 1

[0027] Embodiment one, with reference to figure 1 , a second-stage heating and tempering process method for structural steel, comprising the steps of:

[0028] S1, one-stage heating, heating the structural steel workpiece as a whole, and the first-stage heating temperature is controlled at the lower limit of the normal quenching temperature of the structural steel workpiece; it can refine the grain, reduce the internal stress, greatly reduce the probability of cracks, and reduce deformation and decarburization;

[0029] S2, two-stage heating, secondary heating of the structural steel workpiece as a whole, the second-stage heating temperature is controlled at the upper limit of the normal quenching temperature of the structural steel workpiece; the second stage selects the upper limit of the quenching temperature to ensure the hardening of the larger part of the cross-sectional size of the workpiece effect, and prevent the temperature from dropping too low during the transfer o...

Embodiment 2

[0039] Embodiment 2, this embodiment adds the following technical features on the basis of Embodiment 1:

[0040] Before the step S1, the structural steel workpiece is pretreated as a whole, and the pretreatment includes fillet transition treatment, and the section changes through the fillet transition.

[0041] Example results: appearance: crack rate ≤ 0.5%; hardness: in line with the pattern; depth of hardened layer: in line with the pattern and enterprise standard;

[0042] Metallographic structure: in accordance with GB / T13320, tempered sorbite (+ ferrite) 1-4 grade; deformation, decarburization: does not affect subsequent machining, conforms to the pattern.

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Abstract

The invention discloses a structural steel two-stage heating hardening and tempering process method. The structural steel two-stage heating hardening and tempering process method comprises the following steps that S1, one-stage heating is carried out, specifically, a structural steel workpiece is overall heated, and the first-stage heating temperature is controlled to be the lower limit of the normal quenching temperature of the structural steel workpiece. The structural steel two-stage heating hardening and tempering process method is suitable for the workpiece with the diameter or thicknesslarger than the material hardenability critical diameter or with the large section size change, the first-stage heating temperature selects the lower limit of the normal quenching temperature of steel, grains can be refined, the internal stress is reduced, the probability of cracks is greatly reduced, and deformation and decarburization are reduced; the second-stage heating temperature selects theupper limit of the quenching temperature, the hardenability effect of the large part of the section size of the workpiece is guaranteed, and the situation that the temperature of the small part of the section size is reduced too low in the process of transferring from a heating chamber to a cooling chamber is prevented; the first-stage long-time heating is carried out, and the overall structure transformation of the workpiece is guaranteed; and the second-stage short-time heating is carried out, and the situation that the section size of the workpiece is small or the temperature of the changing part is too high, and consequently defects are generated is prevented.

Description

technical field [0001] The invention belongs to the technical field of structural steel quenching and tempering, and specifically relates to a two-stage heating and tempering process method for structural steel. Background technique [0002] The composite heat treatment process of workpiece quenching and high temperature tempering is called quenching and tempering; the main purpose of quenching and tempering is: first, as the final heat treatment of important mechanical structural parts, so that the workpiece has good comprehensive mechanical properties; second, as a preliminary heat treatment, for For workpieces that require final heat treatment such as surface quenching or chemical heat treatment, make organizational preparations; for high-carbon steel and high-alloy steel workpieces, reduce the hardness to meet the cutting performance. Most of our black machined parts need quenching and tempering treatment, and the material is alloy structural steel. Generally, the deepe...

Claims

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Application Information

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IPC IPC(8): C21D1/25C21D1/74C21D6/00
CPCC21D1/25C21D1/74C21D6/00
Inventor 乔亚杰赵兴旺程孝成孙兴鑫
Owner JIANGSU JUYUAN ELECTRICAL
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