Stainless Steel
About Stainless Steel
Stainless steel is a family of iron-based alloys valued for superior corrosion resistance, strength, and hygienic properties. Grades like 304 offer excellent weldability for general fabrication, while 303 provides enhanced machinability. Common forms include sheet, plate, bar, and pipe. In stock in Los Angeles.
Quick Facts
- Material: Stainless Steel (Austenitic)
- Available Grades: 304/304L, 303
- Available Shapes: Sheet, plate, bar, round, square, flat, angle, pipe, tube
- ASTM Standards: A240, A276, A312, A582
- Location: Los Angeles warehouse
- Services: Custom size, same-day pickup
Overview
Stainless steel is defined by its chromium contentβa minimum of 10.5% by massβwhich creates a passive, self-healing oxide layer on the surface. This microscopic layer prevents rust and corrosion, giving the material its characteristic 'stainless' quality. Beyond corrosion resistance, stainless steels offer high strength, durability, and temperature resistance. The austenitic grades, such as 304, are the most widely used due to their excellent formability and weldability. Their non-porous surface is easy to clean and sanitize, making it a primary material for food, medical, and architectural applications where hygiene is critical.
The two most common grades offered are 304 and 303, each tailored for different fabrication processes. Grade 304 is the versatile industry workhorse, providing a balanced combination of corrosion resistance, formability, and weldability. It is ideal for welded structures, kitchen equipment, and architectural elements. In contrast, Grade 303 is the free-machining variant. By adding sulfur, its composition is altered to produce small, brittle chips during cutting, dramatically improving tool life and machining speeds. This makes it the preferred choice for complex, high-volume machined parts like fasteners, shafts, and fittings.
Technical Specifications
Mechanical Properties - Grade 304/304L
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 73,200 | PSI |
| Yield Strength | 31,200 | PSI |
| Elongation | 70 | % |
| Hardness | 123 | HB |
Mechanical Properties - Grade 303
| Property | Value | Unit |
|---|---|---|
| Tensile Strength | 90,000 | PSI |
| Yield Strength | 35,000 | PSI |
| Elongation | 50 | % |
| Hardness | 228 | HB |
Applicable Standards
- ASTM A240: Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications.
- ASTM A276: Standard Specification for Stainless Steel Bars and Shapes.
- ASTM A312: Standard Specification for Seamless, Welded, and Heavily Cold Worked Austenitic Stainless Steel Pipes.
- ASTM A582: Standard Specification for Free-Machining Stainless Steel Bars.
- ASTM A269: Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service.
Common Applications
- Food & Beverage: Tanks, piping, countertops, and processing equipment (Grade 304) - Due to excellent cleanability and corrosion resistance.
- Machined Components: Nuts, bolts, screws, and fasteners (Grade 303) - Due to superior machinability for high-speed production.
- Architecture & Construction: Cladding, railings, and decorative trim (Grade 304) - For its aesthetic appeal and weather resistance.
- Automotive: Shafts, gears, and complex fittings (Grade 303) - Where intricate shapes require extensive machining.
- Chemical Processing: Storage vessels and fluid handling systems (Grade 304/304L) - For resistance to a wide range of chemicals.
- Medical & Pharmaceutical: Surgical instruments and sterile work surfaces (Grade 304) - For its hygienic and non-reactive properties.
- Marine Hardware: Non-structural fittings and connectors (Grade 303) - Where machinability is prioritized over maximum corrosion resistance.
- Plumbing & Waterworks: Valve bodies and pump components (Grade 303) - For creating precise internal features through machining.
Working with Stainless Steel
Machining
Grade 303 is specifically designed for machinability and is one of the easiest stainless steels to machine. Grade 304 is tougher and more 'gummy', requiring slower speeds, positive feeds, and sharp tooling to prevent work hardening.
Welding
Grade 304 exhibits excellent weldability with all standard fusion methods, both with and without filler metals. Grade 303 is not recommended for welding. The high sulfur content that enhances its machinability can lead to hot cracking in the weld zone.
Finishing
Stainless steel is available in various mill finishes, such as 2B (a smooth, reflective cold-rolled finish on sheet) and can be mechanically polished to achieve finishes from a brushed #4 to a highly reflective #8 mirror finish.
Grades Comparison
| Grade | Tensile (PSI) | Corrosion Resistance | Machinability | Best For |
|---|---|---|---|---|
| 304/304L | 73,200 | Excellent | Fair | General fabrication, welding, forming, food-grade applications |
| 303 | 90,000 | Good | Excellent | High-volume machined parts, fasteners, shafts, fittings |
Frequently Asked Questions
Q: What is the main difference between 304 and 303 stainless steel?
A: The primary difference is machinability versus weldability. 303 contains added sulfur, which makes it excellent for machining but not suitable for welding. 304 is the all-purpose standard with great weldability and formability but is more challenging to machine.
Q: Is stainless steel magnetic?
A: It depends on the grade. Austenitic grades like 304 and 303 are generally non-magnetic in their annealed state. However, they can become slightly magnetic when cold-worked. Ferritic and martensitic grades (like 410) are magnetic.
Q: What does the 'L' in 304L stand for?
A: The 'L' signifies 'Low Carbon' (a maximum of 0.03%). This low carbon content minimizes carbide precipitation during welding, which prevents intergranular corrosion at the weld seams. This makes 304L a better choice for heavy-gauge welded components.
Stock & Custom Sizes
Available in a wide range of shapes including sheet, plate, round bar, flat bar, pipe, and tube. Standard stock lengths for bar products are 12 ft, with structural and pipe lengths up to 21 ft. Sheet and plate are stocked in 4x8 ft and 4x10 ft sizes. Custom size available.
Same-day cutting and Los Angeles pickup available.
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