Method for controlling ferrite content of nitrogen-controlled austenitic stainless steel forge piece

Abstract

The invention discloses a method for controlling ferrite content of a nitrogen-controlled austenitic stainless steel forge piece. The method comprises the following steps of controlling the following components of, in percentage by weight, less than or equal to 0.030% and larger than or equal to 0.025% of C, less than or equal to 0.50% and larger than or equal to 0.40% of Si, less than or equal to 1.90% and larger than or equal to 1.70% of Mn, 9.00-10.00% of Ni, 18.50-20.00% of Cr, less than or equal to 0.080% and larger than or equal to 0.050% of N and the balance Fe and inevitable impurity elements, calculating the ferrite content to be 4% to 10%, and carrying out electric furnace smelting, AOD refining and ESR remelting to obtain the austenitic stainless steel electroslag ingot; then conducting heating at the temperature rising speed smaller than or equal to 100 DEG C / h, conducting heat preservation for not less than 0.6 min / mm when the temperature reaches 1160-1200 DEG C, and using flowing water for quenching after forging; and increasing the temperature to 1050-1070 DEG C for heat preservation for 1-1.2 min / mm, using flowing water for quenching, and obtaining the austenitic stainless steel forge piece with the ferrite content smaller than or equal to 2%. According to the method, the use requirements of key parts in nuclear power equipment are met.

Description

technical field [0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a method for controlling the ferrite content of a nitrogen-controlled austenitic stainless steel forging. Background technique [0002] Many components in the nuclear island equipment are made of austenitic stainless steel, such as reactor internals, some parts in the drive mechanism, the main pipeline of the primary circuit, and the casings of some pumps and valves. There are strict requirements (≤2%). If the chemical composition and processing technology cannot be reasonably controlled, the ferrite content of the material will exceed the standard and affect the use of the product. Therefore, what stable and effective process measures should be adopted to ensure the ferrite content of the product? Qualification is even more critical. [0003] For controlling the ferrite content of austenitic stainless steel forgings, the traditional method is to co...

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Problems solved by technology

[0002] Many components in the nuclear island equipment are made of austenitic stainless steel, such as reactor internals, some parts in the drive mechanism, the main pipeline of the primary circuit, and the casings of some pumps and valves. There are strict requirements (≤2%). If the chemical composition and processing technology cannot be reasonably controlled, the ferrite content of the material will exceed the standard and affect the use of the product. Therefore, what stable and effective process measures should be adopted to ensure the ferrite content of the product? It is very important to qualify

[0003] For controlling the ferrite content of austenitic stainless steel forgings, the traditional method is to control the content of each element in the chemical composition during smelting, and calculate the ferrite content to be ≤2%, but increasing the electrolytic nickel will increase the smelting cost. For this reason, the patent No. CN104250673A proposes a smelting process for reducing the ferrite content of nuclear-grade stainless steel castings, reducing the ferrite content with a small amount of nitrogen, and adding 0.01-0.015% of nitrogen can reduce the ferrite by 0.7-1% content