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Heat treatment method of martensite stainless steel forge piece for nuclear power reactor internals pressure spring

A technology of martensitic stainless steel and heat treatment method, which is applied in the field of heat treatment of martensitic stainless steel forgings used for compression springs of nuclear power reactor internal components, can solve problems such as difficult production and unsatisfactory performance, and achieve the effect of improving comprehensive performance

Inactive Publication Date: 2012-07-11
SHANGHAI HEAVY MACHINERY PLANT
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Problems solved by technology

[0003] Production practice shows that the process specified in this standard is difficult to be directly used in production. If heat treatment is carried out according to the process parameters specified in the standard, the performance that meets the standard cannot be obtained. In fact, it can only meet one of the yield strength or Charpy impact value. If the yield strength is ≥620MPa, the impact value is only 20~30J (joules); if the tempering temperature is increased to the standard upper limit and the holding time is extended to make the impact value ≥48J, the yield strength will be reduced to <600MPa

Method used

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  • Heat treatment method of martensite stainless steel forge piece for nuclear power reactor internals pressure spring
  • Heat treatment method of martensite stainless steel forge piece for nuclear power reactor internals pressure spring
  • Heat treatment method of martensite stainless steel forge piece for nuclear power reactor internals pressure spring

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Embodiment Construction

[0020] Such as figure 1 As shown, the heat treatment method of the martensitic stainless steel forging used for the compression spring of the internal component of the nuclear power reactor of the present invention comprises the following steps:

[0021] The first step, preparatory heat treatment (air quenching);

[0022] Let the workpiece enter the heating furnace, and rapidly heat it to a high temperature of 990-1030°C at a speed of 100±10°C / hour, austenitize and fully dissolve chromium carbide; heat preservation, heat preservation time is 2.5-2.5 to 100mm per heat treatment equivalent thickness 3 hours to confirm; after that, the workpiece is lifted out of the heating furnace and air-cooled to obtain a structure of lath-shaped martensite + a small amount of ferrite;

[0023] The second step, quenching (oil quenching);

[0024] Make the workpiece enter the heating furnace and heat it up to 950-990°C at a speed of 100±10°C / hour; heat preservation, the heat preservation time...

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Abstract

The invention discloses a heat treatment method of a martensite stainless steel forge piece for a nuclear power reactor internals pressure spring, comprising the following steps: step 1, preheating: rapidly heating up a workpiece to 990-1030 DEG C with a speed of 90-110 DEG C / h, preserving heat, and then carrying out air cooling on the workpiece; step 2, quenching: rapidly heating up the workpiece to 950-990 DEG C with a speed of 90-110 DEG C / h, preserving heat, and then carrying out oil cooling to cool the workpiece surface to 100 DEG C; and step 3, high temperature tempering: rapidly heating up the workpiece to 630-670 DEG C with a speed of 90-110 DEG C / h, preserving heat, and then carrying out air cooling on the workpiece to cool to room temperature. According to the invention, by adding the preheating step and optimizing the technological parameters of quenching and tempering, the impact toughness is successfully raised to 120-160 J while raising the yield strength, thus the comprehensive performance of the forge piece is raised.

Description

technical field [0001] The invention relates to a heat treatment method for nuclear power equipment, in particular to a heat treatment method for a martensitic stainless steel forging used for a compression spring of an internal component of a nuclear power pile. Background technique [0002] The compression spring of the internal component of the nuclear power reactor is a key part of the internal component of the million-kilowatt nuclear power reactor. The compression spring forging is made of martensitic stainless steel, and its composition is (weight percentage) C: 0.08~0.14, Cr: 11.50~13.00, Ni: 1.00~1.80, Mn: ≤1.00, Mo: 0.40~0.60, Si≤0.50, N: 0.010~0.030. According to the RCC-M M3205 standard, through heat treatment, the performance of the product can meet the following requirements: yield strength Rp0.2≥620MPa, Charpy KV impact average value≥48J, austenite grain size should be 2.5 or finer (Strive for level 3 or finer). The heat treatment process stipulated in the R...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/22
Inventor 张智峰李向林岳萌张灵芳凌进叶志强
Owner SHANGHAI HEAVY MACHINERY PLANT
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