High chromium ferritic stainless steel 00Cr25Ni4Mo4Ti (UNSS44635) cold and hot workability and heat treatment

00Cr25Ni4Mo4Ti (UNS S44635) High Chromium Ferritic Stainless Steel— Hot and Cold Working and Heat Treatment

High chromium ferritic stainless steel 00Cr25Ni4Mo4Ti (UNS S44635) is one of stainless steels with superior heat and corrosive resistance. It is also called as super ferritic grades, because it delivers excellent combination of weldability and mechanical properties. The common hot and cold working process and heat treatment of 00Cr25Ni4Mo4Ti (UNS S44635) are detailed in this article.

1 Microstructure

00Cr25Ni4Mo4Ti (UNS S44635) has body centered cubic (BCC) structure. The ferritic phase can contain TiC, Cr23C6 and M23C6 carbides. The carbide phase is evenly distributed within the ferrite phase.

2 Hot Working

00Cr25Ni4Mo4Ti (UNS S44635) has good hotformability. It can be hot rolled at 1650°F (900°C) or higher temperature and the best hot rolling temperature is 1742°F (950°C). Annealing should be done after hot rolling and cooling rate should be controlled after finish rolling or annealing in order to avoid the precipitation of titanium carbide. During annealing process, temperature should be controlled at 1650°F to 1742°F (900°C to 950°C).

3 Cold Working

00Cr25Ni4Mo4Ti (UNS S44635) has superior cold formability and it is resistant to tearing and cracking. It has good plasticity when rolling thickness reduce to 0.03 inches. The best rolling temperature should be lower than 68°F (20°C). It is recommended to do stress relief annealing after rolling process to avoid cracking. The best annealing temperature should be lower than temperatures used in hot forming and cooling rate should be controlled sufficiently.

4 Heat Treatment

00Cr25Ni4Mo4Ti (UNS S44635) offers superior resistant to oxidation and carburization and does not need annealing after heat treatment. Moreover, heat treatment process has little impact on the mechanical properties of 00Cr25Ni4Mo4Ti (UNS S44635). Therefore, 00Cr25Ni4Mo4Ti (UNS S44635) requires no heat treatment process, but in special cases, it can be subjected to solution treatment and aging treatment.

In conclusion, hot and cold working process and heat treatment of 00Cr25Ni4Mo4Ti (UNS S44635) are key in order to maximize the performance of 00Cr25Ni4Mo4Ti (UNS S44635) high chromium ferritic stainless steel. Hot rolling temperature should not exceed 1742°F (950°C) and the best cold rolling temperature should be lower than 68°F (20°C). Solution treatment and aging treatment may be used for 00Cr25Ni4Mo4Ti (UNS S44635) in special cases. In conclusion, attention to details during the hot and cold working process and during the heat treatment of 00Cr25Ni4Mo4Ti (UNS S44635) high chromium ferritic stainless steel is key to ensure its excellent welding and mechanical properties and resistance to heat and corrosive environments.

参考：

https://www.hgstainless.com/alloys/ferritic-stainless-steel/00cr25ni4mo4ti-uns-s44635

https://www.bal-tec.com/MATERIALS/Stainless_Steel_AISI446_Heat_Treat_Requirements.pdf

https://www.stainless-sheetmetal.com/datasheet/00cr25ni4mo4ti-uns-s44635-ferritic-grade-stainless-steel-alloy-%E2%80%93-hot-and-cold-working-and-heat-treatment/

00Cr25Ni4Mo4Ti (UNSS44635)

00Cr25Ni4Mo4Ti, also known as UNSS44635, is a high chromium ferritic stainless steel. It is composed of approximately 25% chromium, 4% molybdenum, 4% titanium, 0.20% nitrogen and 0.12% carbon. It has good formability, corrosion resistance and weldability.

00Cr25Ni4Mo4Ti has great corrosion resistance to localized corrosion such as pitting and crevice corrosion, as well as to general corrosion and erosion. It has good resistance to high temperature corrosion, especially in acidic environments and under heat treatment conditions. Moreover, its surface can be further protected by passivation.

00Cr25Ni4Mo4Ti is a stainless steel that can be used for cold forming and hot forming. It is also suitable for heat treatment, including solution annealing, quenching and tempering. The mechanical properties of 00Cr25Ni4Mo4Ti can be enhanced by performing stabilization treatment. This is done by heating the material up to 975-1035°C and holding it for 1-2 hours, followed by rapid cooling.

In conclusion, 00Cr25Ni4Mo4Ti (UNSS44635) is a high chromium ferritic stainless steel suitable for both cold and hot forming and heat treatment. It is resistant to localized and general corrosion and exhibits good resistance to high temperature conditions. Stabilization treatment can further enhance its mechanical properties.