A heat treatment process for improving low-temperature impact performance of super duplex steel

CN120888729BActive Publication Date: 2026-06-19HUZHOU YONGXING SPECIAL STAINLESS STEEL CO LTD

Patent Information

Authority / Receiving Office: CN · China
Patent Type: Patents(China)
Current Assignee / Owner: HUZHOU YONGXING SPECIAL STAINLESS STEEL CO LTD
Filing Date: 2025-09-09
Publication Date: 2026-06-19

AI Technical Summary

Technical Problem

Existing heat treatment processes cannot adaptively adjust to super duplex steel with different compositional fluctuations, leading to the formation of harmful precipitates such as σ phase and Cr2N, which reduces the low-temperature impact performance of super duplex steel.

Method used

By monitoring the temperature and resistance changes of the ingot in real time, a nitrogen atom co-diffusion index and a furnace cooling power correction coefficient are constructed to dynamically control the cooling rate, so as to match the diffusion process of nitrogen atoms from ferrite to austenite and avoid the precipitation of Cr2N phase.

Benefits of technology

It significantly improves the low-temperature impact performance of super dual-phase steel, ensures full diffusion of nitrogen atoms, avoids the formation of harmful phases, and improves the low-temperature performance stability of the material.

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Abstract

This application relates to the field of super dual-phase steel technology, specifically to a heat treatment process for improving the low-temperature impact performance of super dual-phase steel. The process includes: S1: smelting molten steel by adding various elements in a specific weight ratio; S2: continuously casting the molten steel to obtain an ingot; S3: hot-working the ingot, adjusting the cooling rate of the furnace cooling stage based on temperature changes during the hot-working process, and determining a furnace cooling power correction coefficient based on the current ingot temperature change rate and phase transformation activity changes, combined with the nitrogen atom co-diffusion index, to control the cooling rate; S4: surface-treating the hot-worked steel billet to obtain a super dual-phase steel billet. This application addresses the problem that a fixed cooling rate process cannot adapt to fluctuations in material composition and changes in furnace conditions by dynamically adjusting the cooling rate, thereby improving the low-temperature impact performance of super dual-phase steel.

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