Fine Grain Austenitic Stainless Steels AISI 304FG & AISI 316FG Strong and formable alternatives to AISI 304 and AISI 316
General characteristics of AISI 304FG & AISI 316FG
The improved properties of 304FG and 316FG are enabled by smaller grain size (1–6 µm vs. 15–30 µm in conventional 304/316). In addition to superior strength and surface quality, the FG grades offer strong performance in key areas such as corrosion resistance, formability and weldability.
The chemical compositions of the FG-grades are within EN10088-2. They can be formed by common processes and the deep drawing properties are similar to existing deep drawing grades. The FG-grades have good weldability using all common methods used with austenitic stainless steels.
The FG-grades can be used in applications where extra strength or superior surface quality are important. They can be used as an alternative to existing 300-series steels in most applications. The FG-grades are supplied in cold rolled, annealed and pickled condition.
Mechanical properties
Mechanical properties of the steels may be varied by grain size and composition. Typical mechanical properties and stress-strain curve for grade 304FG are presented below.
| Rp0.2 [MPa] | Rm [MPa] | A80 [%] | |
|---|---|---|---|
| Typical AISI 304FG | 450–500 | 750 | ≥40 |
| EN 10088-2 (1.4301) | ≥230 | <750 | ≥45 |
Rp0.2 492 MPa • Rm 773 MPa • Ag 33% • A50 40.3%
Fabrication
The materials can be formed with all standard cold forming methods including deep-drawing, stretch-forming and bending.
The steels have good weldability using methods like MIG/MAG, MIG-laser hybrid, laser and TIG. Materials are suited for autogenous welding. Methods with low heat input are recommended. Post weld heat treatment is not recommended.
pWPS is available for MIG/MAG welding.
Please contact NextInox for more detailed information about welding.
Applications
The application areas for the FG-grades are numerous, including:
- cookware
- sinks
- beer kegs
- heat exchangers
- architectural products.
The unique combination of high strength, formability and high surface quality offers end-users totally new opportunities to redesign their products and/or production processes. High strength enables significant material savings as well as usage savings during lifetime of the product. The excellent surface quality makes processing, such as polishing easier, enabling cost reduction whilst ensuring high level of hygiene and visual appearance.
