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A method for controlling δ ferrite content in martensitic heat-resistant steel

A technology of delta ferrite and control method, which is applied in the field of steel forging and structure control, and can solve problems such as difficult to eliminate and inability to completely eliminate delta ferrite.

Inactive Publication Date: 2016-08-17
UNIV OF SCI & TECH BEIJING +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The control technology of δ ferrite content has always been a difficult point in the production process of martensitic heat-resistant steel. At present, the method of adjusting the chemical composition is mainly used to reduce δ ferrite. The method cannot completely eliminate δ ferrite, and because δ ferrite is a high-temperature precipitated phase, it is difficult to eliminate it by general solution treatment. In addition, some scholars have proposed that the residual δ ferrite content in martensitic heat-resistant steel is related to deformation It is considered that a large amount of deformation can reduce δ ferrite, but the actual deformation can only change the shape of δ ferrite, and cannot completely eliminate δ ferrite.

Method used

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  • A method for controlling δ ferrite content in martensitic heat-resistant steel

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] Example 1: Forging of 1Cr12Ni2Mo2VN steel with a steel ingot shape of Ф430mm×900mm for multiple times

[0039]The chemical composition of 1Cr12Ni2Mo2VN steel is: (C: 0.11%, Si: 0.20%, Mn: 0.75%, Cr: 11.8%, Ni: 2.7%, Mo: 1.7%, V: 0.3%, N: 0.03%)

[0040] 1. First, fully heat the 1Cr12Ni2Mo2VN steel ingot in a heating furnace, heating temperature: 1180°C, heating time: wait for the temperature of each part of the ingot to be uniform and reach 1180°C, and then keep the temperature for 10 hours;

[0041] 2. Deform the fully heated 1Cr12Ni2Mo2VN steel ingot on the forging machine. Deformation system: upsetting and deformation along the axial direction of the ingot to a height of 450mm; after the deformation is completed, the ingot is fully heated in the heating furnace immediately, and the heating temperature is : 1180°C, heating time: After the temperature of each part of the steel ingot is uniform and reaches 1180°C, it is isothermally kept for 4 hours;

[0042] 3. Deform...

Embodiment 2

[0047] Example 2: Forging of 1Cr12Ni2Mo2VN steel with a steel ingot shape of Ф470mm×1000mm for multiple times

[0048] 1. First, fully heat the 1Cr12Ni2Mo2VN steel ingot in a heating furnace, heating temperature: 1190°C, heating time: wait for the temperature of each part of the ingot to be uniform and reach 1190°C, and then hold it for 12 hours;

[0049] 2. Deform the fully heated 1Cr12Ni2Mo2VN steel ingot on the forging machine. The deformation system: upsetting and deformation along the axial direction of the ingot to a height of 500mm; after the deformation is completed, the ingot is fully heated in the heating furnace immediately, and the heating temperature is : 1190°C, heating time: After the temperature of each part of the steel ingot is uniform and reaches 1190°C, it isothermally held for 5 hours;

[0050] 3. Deform the steel ingot that has been upset to a height of 500mm and fully insulated on the forging machine. The deformation system: the steel ingot is elongated ...

Embodiment 3

[0054] Example 3: Forging of 1Cr11Co3W3NiMoVNbNB steel with a steel ingot shape of Ф470mm×900mm for multiple times

[0055] The chemical composition of 1Cr12Ni2Mo2VN steel is: (C: 0.098%, Si: 0.01%, Mn: 0.41%, Cr: 10.57%, Ni: 0.55%, Mo: 0.23%, V: 0.2%, W: 2.48%, Co: 2.74 %, Nb: 0.1%, B: 0.029%, N: 0.03%)

[0056] 1. First, fully heat the 1Cr11Co3W3NiMoVNbNB steel ingot in a heating furnace, heating temperature: 1180°C, heating time: wait for the temperature of each part of the ingot to be uniform and reach 1180°C, and then keep the temperature for 10 hours;

[0057] 2. Deform the fully heated 1Cr11Co3W3NiMoVNbNB steel ingot on the forging machine. Deformation system: upsetting and deformation along the axial direction of the ingot to a height of 450mm; after the deformation is completed, the ingot is fully heated in the heating furnace immediately, and the heating temperature is : 1180°C, heating time: After the temperature of each part of the steel ingot is uniform and reach...

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Abstract

The invention discloses a technique for controlling the content of delta ferrite in martensite thermal-resisting steel, belonging to the technical field of steel forging and tissue control. According to the technique, rammer pull forging processes of temperature keeping, deformation, deformation and temperature keeping are performed for multiple times, so that the delta ferrite in the martensite thermal-resisting steel is eliminated. The technique comprises the following steps: firstly, sufficiently heating and keeping the temperature to eliminate a part of delta ferrite delta ferrite so as to enable steel ingots to be good in plasticity, subsequently performing large deformation so as to increase the specific surface area of the delta ferrite, performing dynamic recrystalization, further keeping the temperature after deformation so as to further reduce the delta ferrite to enable the steel ingots to be good in plasticity and prepare for next deformation, performing the rammer pull forging processes of temperature keeping, deformation, deformation and temperature keeping for multiple times, thereby eliminating the delta ferrite step by step. The technique has the advantage that the delta ferrite in the martensite thermal-resisting steel can be effectively eliminated.

Description

technical field [0001] The invention relates to the technical field of iron and steel forging and microstructure control, in particular to a technology for controlling the delta ferrite content in martensitic heat-resistant steel, specifically to eliminate the delta ferrite microstructure in 1Cr12Ni2Mo2VN steel by using the multiple upsetting and drawing forging technology. Background technique [0002] δ ferrite is a structure that is easy to appear in various martensitic heat-resistant steels. The existence of δ ferrite is not good for the performance of martensitic heat-resistant steels, especially δ ferrite is easy to deform during forging. It is easy to distribute along the axial direction and has an adverse effect on the isotropy of steel, so it must be strictly controlled. GB / T 8732-2004 stipulates that when used as steel for steam turbine blades, the most serious δ ferrite content in the martensitic heat-resistant steels of 2Cr13, 1Cr12Mo, and 2Cr12MoV should not exc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/00C21D6/00
Inventor 刘雅政李俊儒周乐育龚臣陈列佐辉
Owner UNIV OF SCI & TECH BEIJING