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Method for manufacturing fine-grain 35CrNi3MoV steel large forging stock

A manufacturing method and fine-grained technology, applied in the field of manufacturing large forgings, can solve problems such as obvious tissue inheritance, long production cycle, and complicated manufacturing process, and achieve the effect of eliminating tissue inheritance, significant effect, and improving reliability

Active Publication Date: 2015-05-13
JIANGYIN HENGYE FORGING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to invent a method for manufacturing a fine-grained 35CrNi3MoV steel large forging blank, aiming at the problems of complex manufacturing process, high energy consumption, long production cycle, and obvious organizational inheritance after normalizing in the existing 35CrNi3MoV steel large forging blank. It uses large forging ratio forging and isothermal annealing process to suppress the formation of large forged billet flake-like retained austenite so as to cut off and eliminate tissue inheritance, and uniformly refine grains through normal normalizing to provide a good structure for subsequent production

Method used

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  • Method for manufacturing fine-grain 35CrNi3MoV steel large forging stock
  • Method for manufacturing fine-grain 35CrNi3MoV steel large forging stock
  • Method for manufacturing fine-grain 35CrNi3MoV steel large forging stock

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Embodiment 1

[0023] 15 tons of 35CrNi3MoV steel large forging blanks are used for forging. Since the weight of the forging billet exceeds 10 tons, the forging billet should be forged at least 4 times first, the forging ratio of a single forging (1 pier and 1 pullout) is about 3, and the total forging ratio is about 10; then, with 100± Heat the sample from room temperature to 650±10°C at a rate of 10°C / h for about 9 hours, then heat at a rate of 25±5°C / h from 650±10°C to 850±10°C for about 12 hours to ensure that the sample Tensitization is uniform, then cooled at a rate of 30±5°C / h to 640°C±10°C and kept for about 60 hours to form a pearlite-based structure, thereby eliminating tissue inheritance, and then cooled to room temperature; then cooled to room temperature at 100±10 Heat the sample to 650±10℃ and keep it for about 4h at the rate of ℃ / h, then heat it to 860±10℃ at the rate of 25±5℃ / h and keep it for about 15h, and finally take it out and cool it in air to obtain the average grain s...

Embodiment 2

[0027] 7 tons of 35CrNi3MoV steel large forging billet is used for forging. Since the weight of the forging is less than 10 tons, the forging billet can be forged twice at first, the forging ratio of a single forging (1 pier and 1 pull) is about 3, and the total forging ratio is about 5; then, at 100±10°C / Heat the sample from room temperature to 650±10°C for about 9 hours at a rate of h, and then heat it from 650±10°C to 850±10°C for about 12 hours at a rate of 25±5°C / h to ensure that the sample is austenitized Uniform, then cooled to 640°C±10°C at a rate of 30±5°C / h and kept for about 60h to form a pearlite-based tissue, thereby eliminating tissue inheritance, and then cooled to room temperature; followed by 100±10°C / h Heat the sample at a rate of 650±10°C for about 4 hours, then heat it at a rate of 25±5°C / h to 860±10°C for about 15 hours, and finally take it out and cool it in air. The average grain size of prior austenite obtained is 20 ~30mm (such as figure 2 Shown), ...

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Abstract

The invention provides a method for manufacturing a fine-grain 35CrNi3MoV steel large forging stock. The method is composed of large-forging ratio forging, isothermal annealing and normalizing which are carried out sequentially, wherein a large-forging ratio is realized through repeated forging; the isothermal annealing comprises the steps of austenitizing the forging stock, then cooling the forging stock in a furnace at a rate of not higher than 30 DEG C / h until the temperature of the forging stock reaches the nasal tip temperature (640 DEG C) of a pearlite transition zone, and then keeping the temperature for 60h, thereby realizing isothermal decomposition of the pearlite; and then cooling the forging stock to room temperature; in addition, the crystalline grains are fined and homogenized through normal normalization, so that an excellent tissue is provided for subsequent production processing. The method provided by the invention is efficient and reliable, and capable of obtaining original austenite mean grain size being above ASTMNo.8; and therefore, the method is capable of meeting the manufacture requirements of large load-bearing and transmission structural parts in equipment of fire power station, nuclear power station and the like and in large-scale metallurgy, mine and transportation equipment.

Description

technical field [0001] The invention relates to a method for manufacturing large forgings, in particular to a method for manufacturing 35CrNi3MoV steel weighing more than 5 tons, in particular to a method for manufacturing large forging blanks of fine-grained 35CrNi3MoV steel. Background technique [0002] 35CrNi3MoV steel is a medium-carbon medium-alloy steel with high hardenability and good comprehensive mechanical properties. It is often used to manufacture large forgings with high strength and toughness. It is widely used in the manufacture of thermal power, nuclear power and other power station equipment and large-scale metallurgy, mining and transportation. Load-bearing and transmission structural components in equipment. [0003] The final forging temperature of 35CrNi3MoV steel large forging billet (weight more than 5 tons) is high, and air cooling is often used after forging. The non-equilibrium original organization such as martensite and bainite in the crystal is...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D8/00
Inventor 胡华军卞良法卞晓春顾春卫许晓静陆文俊王宏宇陶俊宋振华王子路
Owner JIANGYIN HENGYE FORGING
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