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Heat treatment process for refining FB2 rotor steel grains

A technology of rotor steel and FB2, applied in the field of steel heat treatment process, can solve the problems of coarse grain of FB2 rotor steel, and achieve the effect of solving the problem of coarse grain, improving performance and refining grain.

Inactive Publication Date: 2020-07-14
HARBIN TURBINE
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The present invention proposes a heat treatment process for refining FB2 rotor steel crystal grains in order to solve the problem of coarse grains in the FB2 rotor steel obtained by the existing method

Method used

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  • Heat treatment process for refining FB2 rotor steel grains
  • Heat treatment process for refining FB2 rotor steel grains
  • Heat treatment process for refining FB2 rotor steel grains

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Experimental program
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specific Embodiment approach 1

[0016] Embodiment 1: In this embodiment, the heat treatment process for refining FB2 rotor steel grains is carried out according to the following steps:

[0017] 1. Preliminary heat treatment: heat preservation (0.4-0.6) h / 25mm at 700-770 °C;

[0018] 2. Quenching: heat preservation (0.9-1.1) h / 25mm at 1090-1110 ° C, and the cooling method is oil cooling;

[0019] 3. Tempering for the first time: heat preservation (0.9-1.1) h / 25mm at 560-580 ° C, and the cooling method is air cooling;

[0020] Fourth, the second tempering: keep warm at 670-690°C (0.9-1.1)h / 25mm, and the cooling method is air cooling.

[0021] In this embodiment, by changing the preparatory heat treatment method and keeping it warm for a long time in the temperature range of 700-770°C, pearlite transformation will occur and a new solid phase that is completely different from the original austenite will be formed. The new phase includes ferrite and ferrite The eutectoid structure composed of fine M23(C,B)6 car...

specific Embodiment approach 2

[0022] Embodiment 2: The difference between this embodiment and Embodiment 1 is that in Step 1, heat preservation at 740°C for 0.5h / 25mm. Other steps and parameters are the same as those in the first embodiment.

specific Embodiment approach 3

[0023] Specific embodiment 3: The difference between this embodiment and specific embodiment 1 or 2 is that in step 2, the temperature is kept at 1110°C for 1h / 25mm, and the cooling method is oil cooling. Other steps and parameters are the same as those in Embodiment 1 or 2.

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Abstract

The invention discloses a heat treatment process for refining FB2 rotor steel grains, and relates to a steel heat treatment process. The heat treatment process aims at solving the problem that FB2 rotor steel obtained through treatment of an existing method has coarse grains. The method comprises the steps that heat preservation is conducted at 700 DEG C-770 DEG C for (0.4-0.6) h / 25 mm, and then quenching, first-time tempering and second-time tempering are sequentially conducted. Long-term heat preservation is conducted within the temperature range of 700 DEG C-770 DEG C, pearlite transformation will occur, a solid new phase completely different from original austenite is formed, the new phase comprises ferrite and an eutectoid structure composed of ferrite and fine M23 (C, B) 6 type carbides and borides, the original austenite grain boundary is broken through, and then tissue heredity is eliminated, and the grains of the FB2 rotor steel forge piece are refined. The heat treatment method is suitable for heat treatment of the FB2 rotor steel.

Description

technical field [0001] The invention relates to a steel heat treatment process. Background technique [0002] FB2 rotor steel is a 620°C grade rotor steel, which has been widely used in 600°C and above ultra-supercritical steam turbine units at home and abroad. FB2 rotor steel has excellent creep endurance strength, and the endurance strength at 620°C and 100,000 hours duration exceeds 100MPa. The excellent creep endurance strength is mainly due to the addition of about 100ppm of B element in the steel. B element enters the main strengthening phase M23C6 carbide of steel to form M23(C,B)6 carboboride, which inhibits the aggregation and growth of strengthening phase carbide, improves the stability of carbide, and significantly improves the strength of steel. Creep durable performance. Then, the M23(C,B)6-type carborides mainly exist at the grain boundaries of the prior austenite, and the prior austenite grains are formed during the forging process, and the grains are coars...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18
CPCC21D1/18
Inventor 彭建强刘新新韩亮徐勤冯天澍周立艳李毅刚徐佰明王德彪于海欧魏双胜
Owner HARBIN TURBINE
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