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Method for regulating and controlling boron element distribution state in 9Cr3W3CoB heat-resistant steel for ultra-supercritical unit

An ultra-supercritical unit and element distribution technology, which is applied in the field of thermal deformation, can solve problems such as hindering the optimal distribution of B elements, and achieve the effects of grain refinement, delaying the decline in toughness, and improving durability

Active Publication Date: 2020-04-24
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] Aiming at the problem that a large amount of borides exist in boron-containing 9Cr3W3CoB heat-resistant steel, which hinders the preferred distribution of B elements, the purpose of the present invention is to provide a method for regulating the distribution of boron in 9Cr3W3CoB heat-resistant steel for ultra-supercritical units. Under the premise of changing the chemical composition and smelting process of the existing 9Cr3W3CoB heat-resistant steel, uniform micron-sized grains are obtained through thermomechanical treatment, which eliminates borides in the steel and redissolves B elements into the matrix

Method used

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  • Method for regulating and controlling boron element distribution state in 9Cr3W3CoB heat-resistant steel for ultra-supercritical unit
  • Method for regulating and controlling boron element distribution state in 9Cr3W3CoB heat-resistant steel for ultra-supercritical unit
  • Method for regulating and controlling boron element distribution state in 9Cr3W3CoB heat-resistant steel for ultra-supercritical unit

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Experimental program
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Effect test

Embodiment 1

[0034] In the present embodiment, the chemical composition of 9Cr3W3CoB ultra-supercritical heat-resistant steel is:

[0035] C:0.11%;Cr:9.02%;W:2.99%;Co:3.05%;Cu:0.88%;B:0.015%;Mn:0.46%;Nb:0.073%;V:0.19%;N:0.006%; Si: 0.27%; Ti: 0.015%; Al: 0.013%; P: 0.012%; S: 0.007%; O: 0.002%;

[0036] In the present embodiment, the method for controlling the distribution state of boron in 9Cr3W3CoB heat-resistant steel for ultra-supercritical units is as follows:

[0037] (1) Heat the workpiece at 400°C / h to 1150°C and keep it warm for 1.5h;

[0038] (2) 6-pass rolling is carried out on the workpiece at 1150°C, and the deformation in a single pass is controlled at 10%, so that the final deformation of the workpiece reaches 60%;

[0039] (3) Cool the workpiece to room temperature in air.

[0040] like figure 1 As shown, BN and other borides in the steel are all dissolved, and the B element redissolves back into the matrix.

[0041] The grain size of the ultra-supercritical heat-resis...

Embodiment 2

[0043] In the present embodiment, the chemical composition of 9Cr3W3CoB ultra-supercritical heat-resistant steel is:

[0044] C:0.11%;Cr:9.02%;W:2.99%;Co:3.05%;Cu:0.88%;B:0.015%;Mn:0.46%;Nb:0.073%;V:0.19%;N:0.006%; Si: 0.27%; Ti: 0.015%; Al: 0.013%; P: 0.012%; S: 0.007%; O: 0.002%;

[0045] In the present embodiment, the method for controlling the distribution state of boron in 9Cr3W3CoB heat-resistant steel for ultra-supercritical units is as follows:

[0046] (1) Heat the workpiece at 400°C / h to 1150°C and keep it warm for 2h;

[0047] (2) 6-pass rolling is carried out on the workpiece at 1150°C, and the deformation in a single pass is controlled at 15%, so that the final deformation of the workpiece reaches 90%;

[0048] (3) Air-cool the workpiece to room temperature;

[0049] (4) Temper at 750°C for 1.5h, then air cool to room temperature.

[0050] like figure 2 As shown, all BN and other borides in the steel are dissolved, and the B element dissolves back into the m...

Embodiment 3

[0053] In the present embodiment, the chemical composition of 9Cr3W3CoB ultra-supercritical heat-resistant steel is:

[0054] C:0.11%;Cr:9.02%;W:2.99%;Co:3.05%;Cu:0.88%;B:0.015%;Mn:0.46%;Nb:0.073%;V:0.19%;N:0.006%; Si: 0.27%; Ti: 0.015%; Al: 0.013%; P: 0.012%; S: 0.007%; O: 0.002%;

[0055] In the present embodiment, the method for controlling the distribution state of boron in 9Cr3W3CoB heat-resistant steel for ultra-supercritical units is as follows:

[0056] (1) Heat the workpiece at 400°C / h to 1150°C and keep it warm for 1.5h;

[0057] (2) 6-pass rolling is carried out on the workpiece at 1150°C, and the deformation in a single pass is controlled at 15%, so that the final deformation of the workpiece reaches 90%;

[0058] (3) Air-cool the workpiece to room temperature;

[0059] (4) Aging the workpiece at 800°C for 300h, and air cooling to room temperature.

[0060] like image 3 As shown, BN did not re-nucleate and grow, and the Laves phase was fine and dispersed, and...

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Abstract

The invention belongs to the field of thermal deformation and relates to a method for regulating and controlling a boron element distribution state in 9Cr3W3CoB heat-resistant steel for an ultra-supercritical unit. The method mainly comprises the following steps that: (1) a workpiece is heated to 1150-1200 DEG C, and heat preservation is conducted for 1.5-2 h; (2) the workpiece is subjected to 5-7passes of rolling at the temperature of 1150-1200 DEG C, a single-pass deformation quantity is controlled to be 20% or below, and the final deformation quantity of the workpiece reaches 60%-90%; (3)the workpiece is air-cooled to room temperature; and (4) tempering is conducted for 1-2 h at the temperature of 750-780 DEG C, and air cooling is conducted. According to the thermomechanical treatmentmethod provided by the invention, the distribution of the B element of the steel can be effectively regulated and controlled; boride is completely dissolved; the B element is re-dissolved into a matrix, so that the mechanical property of the workpiece is improved; and the nucleation growth of BN is inhibited in a subsequent high-temperature aging process. The method is suitable for the productionof the boron-containing heat-resistant steel.

Description

technical field [0001] The invention belongs to the field of thermal deformation, and specifically relates to a method for regulating the distribution state of boron in 9Cr3W3CoB heat-resistant steel for ultra-supercritical units. The thermomechanical treatment process can eliminate all borides in the steel, refine the crystal grains, and improve the mechanics of the workpiece. Performance, suitable for the production of boron-containing heat-resistant steel. Background technique [0002] Due to energy and environmental issues, improving the efficiency of thermal power units and developing ultra-supercritical units have become the main demands. Among them, G115 steel, as the representative steel grade of the new 9Cr3W3CoB series new martensitic heat-resistant steel, has become an ideal material for the main steam pipe of the 650 °C ultra-supercritical unit due to its better high-temperature durability. The solid solubility of B element in α-Fe is low, and it is easy to segr...

Claims

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Application Information

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IPC IPC(8): C21D8/00C22C38/00C22C38/02C22C38/04C22C38/06C22C38/20C22C38/22C22C38/24C22C38/26C22C38/28C22C38/30C22C38/32
CPCC21D8/005C22C38/22C22C38/30C22C38/20C22C38/32C22C38/04C22C38/26C22C38/24C22C38/001C22C38/02C22C38/28C22C38/06
Inventor 严伟梁烨杨柯单以银石全强
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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