Large-size maraging stainless steel bar and preparation method thereof

By precisely controlling the vacuum consumable remelting and heat treatment processes, the problem of decreased mechanical properties caused by element segregation in large-size martensitic aging stainless steel bars has been solved, and high-strength stainless steel bars that meet the requirements of aerospace structural components have been produced.

CN121780982APending Publication Date: 2026-04-03CHENGDU ADVANCED METAL MATERIALS IND TECH RES INST CO LTD
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Patent Information

Application Number
CN202610004384.7
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-01-05
Publication Date
2026-04-03

AI Technical Summary

Technical Problem

Existing technologies are insufficient to effectively address the decline in mechanical properties of large-size martensitic aging stainless steel bars due to element segregation after increasing their dimensions.

Method used

By precisely controlling the process steps and parameters of the vacuum consumable remelting stage, combined with improvements in homogenization treatment, rapid forging, and precision forging stages, the uniformity of composition and structure is ensured. Specific chemical composition ratios are adopted, and material properties are improved through solution treatment, cryogenic treatment, and aging heat treatment.

Benefits of technology

Martensitic aging stainless steel bars with excellent mechanical properties, including tensile strength ≥1900MPa, yield strength ≥1600MPa, elongation ≥10%, reduction of area ≥55%, and fracture toughness ≥90MPa·m1/2, are prepared and are suitable for high-tech fields such as aerospace structural components.

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Abstract

The invention relates to the field of metallurgy, and discloses a large-size maraging stainless steel bar and a preparation method thereof, the diameter of the bar is larger than or equal to 300 mm, and the method comprises a vacuum induction melting stage, a vacuum consumable remelting stage, a fast forging cogging stage and a precision forging forming stage; wherein the vacuum consumable remelting stage comprises an arcing stage, a stable smelting stage and a filling smelting stage; in the arc starting stage, a molten pool is formed by adopting a current of 8-12 kA; in the stable smelting stage, the smelting speed is 4.2-4.8 kg / min, the molten drop is 3-5 s <-1 >, the molten drop short-circuit time is 0.6-0.8 s, and inert gas is started to be filled for cooling after smelting is conducted by the preset weight; and in the filling smelting stage, inert gas filling is stopped, and the current and the melting speed are controlled to descend in a stepped mode. According to the method, the uniformity of components and structures can be improved, so that the mechanical property of the large-size maraging stainless steel bar is improved.
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