A method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃
By employing specific forging and heat treatment methods, the problem of insufficient yield strength of 06Cr18Ni11Ti forgings at 350℃ was solved, thereby improving the high-temperature yield strength of the forgings and meeting the performance requirements of nuclear-grade products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUIZHOU AEROSPACE XINLI CASTINGSAND FORGINGS
- Filing Date
- 2023-12-19
- Publication Date
- 2026-05-26
AI Technical Summary
Conventional heat treatment processes cannot meet the yield strength requirements of 06Cr18Ni11Ti forgings at 350℃, especially for nuclear-grade forgings, where the high-temperature yield strength requirement has a pass rate of only 40%.
Specific forging and heat treatment methods are employed, including heating and holding steps of the preform, combined with upsetting, drawing, forging and forming processes, controlling the final forging temperature and performing water cooling treatment to ensure that the forging has sufficient yield strength at high temperatures.
The yield strength at 350℃ of 06Cr18Ni11Ti forgings was significantly improved, reaching or exceeding the requirement of 176MPa, thus enhancing the high-temperature performance of the material.
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Figure BDA0004616091150000031
Abstract
Description
Technical Field
[0001] This invention relates to the field of hot working technology of metallic materials, specifically to a method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃. Background Technology
[0002] 06Cr 18 Ni 11 Ti (steel grade S32168) stainless steel is a Ni-Cr-Ti type austenitic steel with excellent plasticity, toughness, wear resistance, high temperature resistance, and creep resistance. It is used in the manufacture of linings for wear-resistant containers and equipment, pipelines, and in industries such as petrochemicals, power generation, bridges, and automobiles. Its properties are similar to 304 stainless steel, but the addition of titanium gives it better resistance to intergranular corrosion and higher temperature strength. The addition of titanium also effectively controls the formation of chromium carbide, increasing its corrosion resistance.
[0003] For products that only require room temperature mechanical properties, the requirements can be met by conventional solution heat treatment. However, due to the continuous expansion of market demand for this material, more and more medium and large nuclear power products are using this material. Generally, the yield strength requirement for a tensile test at 350℃ is ≥125MPa. However, a certain nuclear-grade forging has raised the yield strength requirement at 350℃ to 176MPa. Using conventional forging and heat treatment methods, the pass rate is extremely low, only about 40%.
[0004] Therefore, this application provides a forging and heat treatment method to improve the performance of 06Cr. 18 Ni 11 The yield strength of Ti material forgings at 350℃ is ≥125MPa. Summary of the Invention
[0005] The present invention aims to provide a method for improving the performance of 0.6Cr. 18 Ni 11 A method for achieving a high-temperature yield strength of 350℃ for Ti forgings, to address the inability of conventional heat treatment processes to meet the requirements of 06Cr. 18 Ni 11 Yield strength requirements for Ti material forgings at 350℃.
[0006] To address the above problems, the present invention provides the following technical solution:
[0007] A method to improve 0.6Cr 18 Ni 11 A method for achieving high-temperature yield strength of Ti forgings at 350℃ includes the following steps:
[0008] S1. Forging of precast billets: Heat the billet to 400-450℃, hold it at 0.6-0.8 min / mm according to its thickness, raise the temperature to 820-850℃ in the furnace, hold it at 0.8-1.0 min / mm, and then raise the temperature to 1160-1180℃ in the furnace, hold it at 0.6-0.8 min / mm.
[0009] After exiting the furnace, the material is upset and drawn, with an upsetting ratio of 4 or higher. The final forging temperature is controlled above 850℃, and the material is immediately water-cooled after forging.
[0010] S2. Forging and forming: The precast billet is heated to 1060-1080℃ in the furnace. The holding time is calculated according to the billet thickness at 0.6-0.8 min / mm. After holding, the billet is taken out of the furnace for forging.
[0011] During forging, an upper and lower flat anvil are used to press the thickness and width of the precast billet down to the required forging size. The final forging temperature is controlled above 920℃, and the forging is immediately water-cooled after forging.
[0012] Further, S1, forging of precast billets: the billet is heated to 400℃, held at 0.6 min / mm according to its thickness, then heated to 820℃ in the furnace, held at 0.8 min / mm, and then heated to 1160℃ in the furnace, held at 0.6 min / mm; S2, forging and forming: the precast billet is heated to 1060℃ in the furnace, the holding time is calculated according to the billet thickness at 0.6 min / mm, and after holding, it is taken out of the furnace for forging.
[0013] Further, S1, forging of precast billets: the billet is heated to 450℃, held at 0.6 min / mm according to its thickness, then heated to 850℃ in the furnace, held at 0.8 min / mm, and then heated to 1180℃ in the furnace, held at 0.6 min / mm; S2, forging and forming: the precast billet is heated to 1080℃ in the furnace, the holding time is calculated according to the billet thickness at 0.8 min / mm, and after holding, it is taken out of the furnace for forging.
[0014] Further, S1, forging of precast billets: the billet is heated to 450℃, and held at 0.8 min / mm according to its thickness. The temperature is then raised to 850℃ in the furnace, and held at 1.0 min / mm. The temperature is then raised to 1180℃ in the furnace, and held at 0.8 min / mm. S2, forging and forming: the precast billet is heated to 1080℃ in the furnace. The holding time is calculated according to the billet thickness at 0.8 min / mm. After holding, the billet is taken out of the furnace for forging.
[0015] Furthermore, the dimensions of the precast billet are designed based on the deformation amount in the next forming process, with a deformation amount of 15±3% set in both the width and thickness directions. Detailed Implementation
[0016] The following detailed description illustrates the specific implementation methods:
[0017] 06Cr is used 18 Ni 11 Ti-grade forging, forging specifications: φ160×500, material: 06Cr 18 Ni 11 The chemical composition of the Ti forgings is shown in Table 1 below. Table 1 Chemical Composition of Forgings
[0018] C Mn Yes P S Cr Nor I will You 0.054 1.62 0.54 0.021 0.001 18.04 9.67 0.03 0.44
[0019] Example 1: The specific heat treatment method includes the following steps:
[0020] S1. Forging of precast billets: Heat the billet to 450℃, hold it at 0.6 min / mm according to its thickness, raise the temperature to 850℃ in the furnace, hold it at 0.8 min / mm, and then raise the temperature to 1180℃ in the furnace, hold it at 0.6 min / mm.
[0021] After exiting the furnace, the material is upset and drawn, with an upsetting ratio of 4 or higher. The final forging temperature is controlled at 850℃, and the material is immediately water-cooled after forging.
[0022] The dimensions of the precast billet are designed based on the deformation amount in the next forming process, with a deformation amount of 15±3% set in both the width and thickness directions.
[0023] S2. Forging and forming: The precast billet is heated to 1080℃ in the furnace. The holding time is calculated according to the billet thickness at 0.8min / mm. After holding, the billet is taken out of the furnace for forging.
[0024] During forging, an upper and lower flat anvil are used to press the thickness and width of the precast billet down to the required forging size. The final forging temperature is controlled at 920℃, and the forging is immediately water-cooled after forging.
[0025] Example 2: The difference from Example 1 is that, S1, forging of precast billets: the billet is heated to 400°C, held at 0.6 min / mm according to its thickness, then heated to 820°C in the furnace, held at 0.8 min / mm, and then heated to 1160°C in the furnace, held at 0.6 min / mm; S2, forging: the precast billet is heated to 1060°C in the furnace, the holding time is calculated according to the billet thickness at 0.6 min / mm, and after holding, it is taken out of the furnace for forging.
[0026] Example 3: The difference from Example 1 is that, S1, forging of precast billets: the billet is heated to 450°C, held at 0.8 min / mm according to its thickness, then heated to 850°C in the furnace, held at 1.0 min / mm, and then heated to 1180°C in the furnace, held at 0.8 min / mm; S2, forging: the precast billet is heated to 1080°C in the furnace, the holding time is calculated according to the billet thickness at 0.8 min / mm, and after holding, it is taken out of the furnace for forging.
[0027] Comparative Example: 06Cr with the same specifications and composition as in Example 1 was used. 18 Ni 11 Ti core-grade forgings, the specific heat treatment method includes the following steps: (1) Solution heating: Heat the furnace for 5 hours, and start heat preservation when the thermocouple temperature reaches 1060℃; (2) Heat preservation: Start heat preservation at 1060℃ and keep it for 2 hours; (3) Solution cooling: After heat preservation, remove from the furnace and cool with water to below 100℃.
[0028] Examples 1-3 and the comparative examples were subjected to room temperature tensile testing and 350°C tensile testing. The results are shown in the table below:
[0029]
[0030] As can be seen from the table above, in Examples 1 to 3, the room temperature tensile strength and the 350°C tensile strength are both better than those of conventional methods, and the 350°C yield strength is greater than 176 MPa. Therefore, the processing method of this application meets the mechanical performance requirements.
[0031] For those skilled in the art, numerous modifications and improvements can be made without departing from the inventive concept of this invention. These modifications and improvements should also be considered within the scope of protection of this invention, and will not affect the effectiveness of the invention or the practicality of the patent. The scope of protection claimed in this application shall be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.
Claims
1. A method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃, characterized in that, Includes the following steps: S1. Forging of precast billets: Heat the billet to 400-450℃, hold it at 0.6-0.8 min / mm according to its thickness, raise the temperature to 820-850℃ in the furnace, hold it at 0.8-1.0 min / mm, and then raise the temperature to 1160-1180℃ in the furnace, hold it at 0.6-0.8 min / mm. After exiting the furnace, the material is upset and drawn, with an upsetting ratio of 4 or higher. The final forging temperature is controlled above 850℃, and the material is immediately water-cooled after forging. S2. Forging and forming: The precast billet is heated to 1060-1080℃ in the furnace. The holding time is calculated according to the billet thickness at 0.6-0.8 min / mm. After holding, the billet is taken out of the furnace for forging. During forging, an upper and lower flat anvil are used to press the thickness and width of the precast billet down to the required forging size. The final forging temperature is controlled above 920℃, and the forging is immediately water-cooled after forging.
2. The method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃ according to claim 1, characterized in that, S1. Forging of precast billets: Heat the billet to 400℃, hold it at 0.6 min / mm according to its thickness, raise the temperature to 820℃ in the furnace, hold it at 0.8 min / mm, raise the temperature to 1160℃ in the furnace, and hold it at 0.6 min / mm. S2. Forging and forming: The precast billet is heated to 1060℃ in the furnace. The holding time is calculated according to the billet thickness at 0.6min / mm. After holding, the billet is taken out of the furnace for forging.
3. The method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃ according to claim 1, characterized in that, S1. Forging of precast billets: Heat the billet to 450℃, hold it at 0.6 min / mm according to its thickness, raise the temperature to 850℃ in the furnace, hold it at 0.8 min / mm, and then raise the temperature to 1180℃ in the furnace, hold it at 0.6 min / mm. S2. Forging and forming: The precast billet is heated to 1080℃ in the furnace. The holding time is calculated according to the billet thickness at 0.8min / mm. After holding, the billet is taken out of the furnace for forging.
4. The method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃ according to claim 1, characterized in that, S1. Forging of precast billets: Heat the billet to 450℃, hold it at 0.8 min / mm according to its thickness, raise the temperature to 850℃ in the furnace, hold it at 1.0 min / mm, and then raise the temperature to 1180℃ in the furnace and hold it at 0.8 min / mm. S2. Forging and forming: The precast billet is heated to 1080℃ in the furnace. The holding time is calculated according to the billet thickness at 0.8min / mm. After holding, the billet is taken out of the furnace for forging.
5. The method for improving the high-temperature yield strength of 06Cr18Ni11Ti forgings at 350℃ according to any one of claims 1 to 4, characterized in that, The dimensions of the precast billet are designed based on the deformation amount in the next forming process, with a deformation amount of 15±3% set in both the width and thickness directions.