Technical Guide

This technical guide provides in-depth information on the physical, mechanical, and chemical properties of stainless steel, along with international standards, testing methods, and engineering best practices. It serves as a reference for designers, fabricators, and end-users to ensure proper specification and performance. Common forms include stainless steel sheets and pipes.

Physical Properties of Stainless Steel

• Density: 7.7–8.0 g/cm³ (slightly less than carbon steel).
• Melting Point: 1375–1530°C depending on grade.
• Thermal Conductivity: 14–19 W/m·K (lower than carbon steel).
• Coefficient of Thermal Expansion: 16–18 × 10⁻⁶ /°C (higher than carbon steel).
• Electrical Resistivity: 70–85 μΩ·cm (higher than carbon steel).
• Magnetic Properties: Austenitic grades non-magnetic; ferritic and martensitic magnetic.

Mechanical Properties (Typical Values)

Corrosion Resistance and Types of Corrosion

1. General Corrosion: Uniform attack in aggressive acids.
2. Pitting Corrosion: Localized attack, especially in chloride environments.
3. Crevice Corrosion: Occurs in tight gaps.
4. Stress Corrosion Cracking (SCC): Combination of tensile stress and chlorides.
5. Intergranular Corrosion: Occurs in sensitized zones near welds.

Standards and Specifications

• ASTM: A240 (plate), A276 (bar), A312 (pipe), A479 (forgings).
• EN: EN 10088 (flat products), EN 10217 (welded tubes).
• ISO: ISO 3506 (fasteners), ISO 15510 (chemical composition).
• JIS: JIS G4304 (plate), G4305 (sheet).

Welding Stainless Steel

• Recommended Methods: TIG, MIG, plasma, resistance welding.
• Filler Metals: Match or overmatch base metal composition.
• Post-Weld Treatment: Pickling and passivation to restore corrosion resistance.
• Avoid: Carbon steel contamination, excessive heat input.

Forming and Fabrication

• Bending: Minimum bend radius 2–3 × thickness.
• Machining: Lower speeds than carbon steel, use sharp tools.
• Deep Drawing: Austenitic grades have excellent drawability.

Testing Methods

• Tensile Testing: ASTM E8.
• Hardness Testing: Rockwell, Brinell, Vickers.
• Corrosion Testing: ASTM G48 (pitting), G28 (intergranular).
• Non-Destructive Testing: Ultrasonic, dye penetrant, radiography.

Best Engineering Practices

• Select grade based on environment and temperature.
• Specify proper surface finish.
• Use low-carbon or stabilized grades for welding.
• Apply passivation after fabrication.
• Design for thermal expansion.

This technical guide equips professionals with the knowledge to specify, fabricate, and maintain stainless steel components correctly and reliably. For specific grade information, see 300 series stainless steel options.