Stainless Steel
Corrosion-resistant steel alloys (303, 304, 316, 17-4 PH) offering an excellent balance of strength, durability, and chemical resistance for demanding environments.
About Stainless Steel
Stainless steel is the material of choice when corrosion resistance, strength, and hygiene are critical. The chromium content (minimum 10.5%) forms a self-healing oxide layer that protects against rust and chemical attack, making it indispensable in medical, food processing, marine, and chemical environments.
FabRapid machines all major stainless steel families: austenitic (303, 304, 316), martensitic (410, 420, 440C), precipitation-hardened (17-4 PH), and duplex grades. Each grade offers a different balance of corrosion resistance, strength, machinability, and cost. Our experienced machinists optimize cutting parameters for each grade to minimize work hardening and achieve superior surface finishes.
Passivation treatment per ASTM A967 is available for all stainless steel parts, maximizing the natural corrosion resistance of the chromium oxide layer. We also offer electropolishing for medical and pharmaceutical parts requiring ultra-smooth, crevice-free surfaces.
Material Properties
Available Alloy Grades
303
Free-machining austenitic grade with added sulfur for improved machinability. Slightly reduced corrosion resistance compared to 304.
Shafts, fittings, fasteners, valve components, and high-volume machined parts
304
The most widely used stainless steel with excellent corrosion resistance, formability, and weldability. The standard for food and architectural applications.
Food processing equipment, kitchen hardware, architectural fixtures, chemical containers
316
Molybdenum-enhanced austenitic grade with superior corrosion resistance, especially against chlorides and marine environments.
Marine hardware, chemical processing, pharmaceutical equipment, surgical implants
17-4 PH
Precipitation-hardened martensitic grade achieving high strength (up to 1310 MPa) through aging heat treatment. Combines strength with good corrosion resistance.
Aerospace structural parts, valve stems, nuclear components, high-performance shafts
Compatible Manufacturing Processes
Stainless Steel can be processed using these manufacturing methods.
Available Surface Finishes
Surface treatments compatible with Stainless Steel.
Common Applications
Design Guidelines for Stainless Steel
Use sharp, coated carbide tools — stainless steel work-hardens quickly with dull tools
Minimum wall thickness: 0.8 mm (thicker than aluminum due to spring-back tendency)
Specify 303 for complex machined parts to reduce cost — it machines 2× faster than 304
For welded assemblies, specify 304L or 316L (low-carbon) to prevent intergranular corrosion
Avoid deep narrow slots — stainless steel generates significant heat and requires adequate chip evacuation
Stainless Steel FAQ
316 contains 2-3% molybdenum, which provides significantly better resistance to chloride corrosion and marine environments. 304 is more cost-effective and sufficient for most indoor and freshwater applications. For medical, marine, or chemical processing, 316 is the standard choice.
Austenitic grades (303, 304, 316) cannot be hardened by heat treatment — they can only be work-hardened. Martensitic (410, 420, 440C) and precipitation-hardened (17-4 PH) grades can be heat-treated to high hardness levels. 17-4 PH can reach 44 HRC through H900 aging.
Austenitic grades (303, 304, 316) are generally non-magnetic in the annealed condition, though cold working can induce slight magnetism. Martensitic (410, 17-4 PH) and ferritic grades are magnetic. If non-magnetic properties are critical, specify austenitic grade in annealed condition.
Machining can embed free iron particles from cutting tools into the stainless steel surface, creating initiation sites for rust. Passivation removes these contaminants and enhances the natural chromium oxide protective layer. It is especially important for medical, food-contact, and marine applications.
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