Product Description
654 SMO (UNS S32654) is a high-performance austenitic stainless steel with exceptional corrosion resistance properties. With unusually high levels of chromium (24%), molybdenum (7-8%), and nitrogen (0.45-0.55%), 654 SMO achieves levels of chloride pitting and crevice corrosion resistance not previously possible with an austenitic stainless steel. This innovative grade represents advanced stainless steel technology, offering twice the strength of common austenitic stainless steels while maintaining excellent ductility and toughness.
654 SMO features a fully austenitic structure and is designed to handle the most demanding corrosive environments. It provides superior workability, formability, and weldability, making it an ideal choice for critical applications in aggressive environments where standard stainless steels would fail.
Applications
654 SMO stainless steel’s exceptional corrosion resistance properties make it suitable for a wide range of challenging applications:
- Critical seawater and severe brackish water handling systems
- Chlorine and chlorine dioxide pulp bleaching systems
- Chemical processing equipment
- Desalination systems
- Municipal waste incineration systems
- Plate heat exchangers
- Equipment exposed to high-chloride environments
- Applications requiring resistance to pitting, crevice corrosion, and stress corrosion cracking
654 SMO is particularly valuable in industries where equipment failure would result in costly downtime, making it an economical long-term solution despite its higher initial cost compared to conventional stainless steels.
Standards
654 SMO (UNS S32654) meets the following standards for various product forms:
American Standards:
- ASTM A240/A480 (Plate and Sheet)
- ASTM A249 (Tube)
- ASTM A312 (Pipe)
- ASTM A358 (Pipe)
ASME Standards:
- ASME SA-240 (Plate and Sheet)
- ASME SA-312 (Pipe)
- ASME SA-358 (Pipe)
- ASME SA-480 (Plate and Sheet)
- ASME Code Case 2195
Chemical Composition and Grade Specifications
Grade Equivalents
UNS S32654 – 654 SMO
Chemical Composition
| Element | ASTM Specification (S32654) | Typical |
|---|---|---|
| Carbon (C) | 0.020 max | 0.010 |
| Chromium (Cr) | 24.0-25.0 | 24.0 |
| Nickel (Ni) | 21.0-23.0 | 22.0 |
| Molybdenum (Mo) | 7.0-8.0 | 7.3 |
| Nitrogen (N) | 0.45-0.55 | 0.50 |
| Copper (Cu) | 0.30-0.60 | 0.50 |
| Sulfur (S) | 0.005 max | 0.001 |
| Phosphorus (P) | 0.030 max | 0.020 |
| Silicon (Si) | 0.50 max | 0.40 |
| Manganese (Mn) | 2.00-4.00 | 3.00 |
| Iron (Fe) | Balance | Balance |
Mechanical Properties
| Property | Value at 68°F (20°C) |
|---|---|
| 0.2% Yield Strength, min (ksi) | 62 |
| Tensile Strength, min (ksi) | 109 |
| Elongation, min (%) | 40 |
| Hardness, max (HBN) | 250 |
| Impact Strength, min (ft·lb/in²) | 106 |
Corrosion Resistance
654 SMO offers exceptional resistance to:
- Pitting and crevice corrosion – with a PRE (Pitting Resistance Equivalent) of 56.1, significantly higher than other stainless steels
- Chloride stress corrosion cracking (SCC)
- General corrosion in acids including sulfuric, hydrochloric, hydrofluoric, and fluosilic acids
- Erosion corrosion in seawater
Heat Treatment
654 SMO is solution annealed at minimum 2100°F (1150°C) followed by water quenching to achieve a fully austenitic stainless steel structure. The high-temperature annealing and rapid cooling prevent the formation of intermetallic phases that could reduce corrosion resistance and toughness.
Physical Properties
| Property | 68°F (20°C) |
|---|---|
| Density (lb/in³) | 0.289 |
| Modulus of elasticity (×10⁶ psi) | 27.4 |
| Thermal conductivity (Btu·in/ft²·h·°F) | 0.017 |
| Heat capacity (Btu/lb·°F) | 0.120 |
| Electrical resistivity (×10⁶ Ω·in) | 30.7 |
Available Dimensions
Plate
Thickness: 3mm to 100mm
Width: 1000mm to 3000mm
Length: 2000mm to 12000mm
Sheet
Thickness: 0.5mm to 6mm
Width: 600mm to 2000mm
Length: 1000mm to 6000mm
Strip
Thickness: 0.1mm to 3mm
Width: 10mm to 600mm
Length: As required or coil form
Bar
Diameter: 8mm to 300mm
Length: 3000mm to 6000mm
Pipe and Tubing
Outside Diameter: 6mm to 610mm
Wall Thickness: 0.5mm to 50mm
Length: 3000mm to 12000mm or as required
Fabrication Information
Welding
654 SMO possesses good weldability and can be welded using conventional welding methods applied to common austenitic stainless steels. For optimal results, an overalloyed filler metal should be used when the weld will not be subsequently annealed. Proper welding procedures include:
- Using appropriate filler metals for all welding methods
- Establishing full penetration with minimal dilution
- Using proper shielding gases (argon or argon with nitrogen)
- Thorough post-weld cleaning for optimal corrosion resistance
Forming
654 SMO has very good cold formability despite its high strength. Due to its high work hardening rate, higher forming forces and increased allowance for springback are necessary. Hot working should be carried out in the 2200°F to 2000°F (1205°C to 1095°C) range, followed by proper annealing and quenching.
Machining
The high strength, toughness, and work hardening of 654 SMO make machining more challenging than common austenitic grades. Powerful, rigid equipment, reduced speeds and feeds, and superior lubrication are necessary for effective machining.
Why Choose FUSHUN METAL for 654 SMO Products
FUSHUN METAL is your trusted partner for high-performance 654 SMO stainless steel products. Our commitment to quality and service makes us the preferred supplier for industries requiring exceptional corrosion resistance materials:
- Comprehensive inventory of 654 SMO products in various forms including plate, sheet, strip, bar, pipe, and tubing
- Strict quality control procedures ensuring all 654 SMO products meet or exceed industry standards
- Technical expertise to assist with material selection, application advice, and fabrication guidance
- Custom cutting and processing capabilities to meet your specific requirements
- Competitive pricing and reliable delivery schedules
- Long-term experience serving industries that depend on high-performance stainless steel
When your application demands the exceptional corrosion resistance and mechanical properties of 654 SMO stainless steel, contact FUSHUN METAL for a detailed quotation. Our technical team is ready to assist with your material requirements and provide the information you need to make informed decisions for your critical applications.
