Annealing method for improving intergranular corrosion resistance of super ferritic stainless steel

Through the three-stage continuous annealing method, nano-scale Laves phase is preprecipitated, recrystallized and refined grains are refined, and the problems of intergranular corrosion resistance and fine grains in the existing technology are solved through high temperature and short-term redissolution annealing, and the high corrosion resistance and excellent mechanical properties of special super ferrite stainless steel are achieved.

CN119662940AActive Publication Date: 2025-03-21ZHONGBEI UNIV
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Patent Information

Application Number
CN202411957456.7
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-12-30
Publication Date
2025-03-21
Estimated Expiration
2044-12-30

AI Technical Summary

Technical Problem

While improving the intergranular corrosion resistance of extra super ferrite stainless steel, the prior art is difficult to ensure that the grains are small, resulting in a decrease in the mechanical properties of the material.

Method used

Three-stage continuous annealing method is adopted, including preprecipitation annealing, recrystallization annealing and redissolution annealing. The grains are refined by preprecipitation of nano-scale Laves phases and recrystallization, and the grain boundary Laves phase is dissolved through high temperature and short-term redissolvation annealing to precipitate Nb(C,N) particles to inhibit grain coarseness.

Benefits of technology

It effectively improves the intergranular corrosion resistance of extra super ferrite stainless steel, while maintaining the fine grains and improving the mechanical properties of the material.

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Abstract

The invention relates to the technical field of ferritic stainless steel, in particular to an annealing method for improving intergranular corrosion resistance of super ferritic stainless steel. In order to solve the problem of how to improve a recrystallization annealing process so as to improve the intergranular corrosion resistance of a stainless steel plate and ensure fine grains, the invention provides a novel annealing method for improving the intergranular corrosion resistance of the super ferrite stainless steel, which comprises the steps of three-stage continuous annealing, pre-precipitation annealing and pre-precipitation of a nanoscale Laves phase, recrystallization annealing plays a role in pinning grain boundaries to refine grains, lastly, Laves phases are dissolved at high temperature through redissolution annealing, Nb, Mo and Si elements are dissolved near the grain boundaries, Nb (C, N) particles are separated out, and the dragging effect of Nb, Mo and Si solute elements is used for inhibiting grain coarsening and improving the grain size. The intergranular corrosion resistance of the ultra-super ferritic stainless steel is improved, meanwhile, it is guaranteed that grains of the ultra-super ferritic stainless steel are small, and the mechanical property of the ultra-super ferritic stainless steel is guaranteed.
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