Corrosion-proof. Medical-grade. Autoclavable.
304, 316L, 17-4 PH and specialty grades. From food-service hardware to implant prototypes to aerospace structural components. Full passivation and electropolishing in-house.
At a glance
- Density
- 8.00 g/cc
- Yield strength
- 205 MPa
- Tensile strength
- 515 MPa
- Elongation
- 40 %
- Hardness
- 217 HB max
- Melting range
- 1,371–1,399 °C
- Thermal cond.
- 16 W/m·K
- Corrosion
- Excellent (Mo-alloyed)
Key data
- Density
- 8.00 g/cc
- Yield strength
- 205 MPa
- Tensile strength
- 515 MPa
- Elongation
- 40 %
- Hardness
- 217 HB max
- Melting range
- 1,371–1,399 °C
- Thermal cond.
- 16 W/m·K
- Corrosion
- Excellent (Mo-alloyed)
Common stainless grades.
304 / 304L
General-purpose austenitic. Excellent corrosion resistance for most environments. Non-magnetic in annealed state. Non-heat-treatable. 304L has lower carbon for better weldability.
316L
Adds molybdenum (2–3%) for superior chloride resistance. Standard for marine, medical implants, pharmaceutical, and chemical processing. Low carbon version for welded assemblies.
17-4 PH
Martensitic precipitation-hardening. Heat-treatable to 1,100 MPa yield. Aerospace shafts, valve bodies, flight hardware. H900, H1025 and H1150 tempers.
303
Adds sulfur and selenium for improved machinability — turns 2–3× faster than 304. Used for high-volume turned parts: shafts, bushings. Slightly less corrosion resistant than 304.
15-5 PH
Similar to 17-4 PH with better transverse toughness. Aerospace structural applications requiring precipitation hardening.
Duplex 2205
Two-phase austenitic-ferritic. Exceptional stress-corrosion cracking resistance. Offshore, chemical processing, pulp and paper. NACE MR0175 capable.
Five grades cover the vast majority of stainless steel applications. The right choice comes down to corrosion environment, strength, and whether you need to heat-treat.
What makes stainless stainless.
Corrosion resistance
Self-healing Cr2O3 passive layer resists attack from water, most chemicals, and biological fluids. Enhanced in 316L with molybdenum.
Biocompatibility
316L certified for short-term implant contact. Standard alloy for surgical instruments, bone plates, medical fixtures.
High temperature
Maintains strength to 500 °C (304) or 800 °C (316). Oxidation resistance to 900 °C and beyond.
Hygienic surface
Electropolished or passivated surfaces are FDA/USDA compliant for food, dairy, pharmaceutical and medical.
The defining property is the chromium oxide passive layer that self-heals on exposure to oxygen. This single feature drives every design choice with stainless.
Where stainless is the answer.
Medical instruments
316L surgical tools, bone screws, retractors — passivated, electropolished
Pharmaceutical hardware
316L tanks, piping, valve bodies — cGMP finish Ra 0.4 µm
Marine hardware
316L cleats, pulpits, rigging — chloride-resistant
Aerospace
17-4 PH valves, shafts, actuators — H1025 or H900 temper
Food & dairy
304 tanks, fittings, conveyor parts — 3-A sanitary
Chemical processing
316L, duplex 2205 reactor bodies, heat exchangers
Oil & gas
Duplex, 316L downhole tools — NACE MR0175 sour-service
Architectural
304 #4 brushed railings, facades, kitchen appliances
Firearms & sport
17-4 PH, 440C cutlery and firearm components
Finishing options for stainless.
Passivation
ASTM A967 citric or nitric — removes free iron, enhances Cr oxide layer. Required for medical.
Electropolishing
Electrochemical polish removes surface irregularities. Reduces bacteria adhesion. Used for pharma.
Bead blasting
Uniform matte cosmetic finish. Hides small surface defects. Common for medical instruments.
#4 brushed
Unidirectional polish pattern. Architectural appliance finish. Non-directional ("#7") on request.
Mirror polish
Up to Ra 0.05 µm (SPI-A1 grade) achievable. For optical and show-surface applications.
Laser etching
Permanent mark for serial numbers, logos, regulatory markings. No paint, no wear-off.
Titanium coloring
Heat or electrochemical coloring produces surface oxide in gold, blue, purple. Surgical tool coding.
Chrome plating
Hard chrome for wear surfaces. Decorative chrome for cosmetic. Thickness 5–25 µm.
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Corrosion-proof — questions
What is the difference between 304 and 316L?
316L contains 2–3% molybdenum that 304 does not. Molybdenum dramatically improves resistance to chloride-induced pitting corrosion — the mechanism that attacks stainless in salt water, chlorinated pools, and bodily fluids. 316L is standard for marine, medical and food processing. 304 is fine for most indoor applications.
Can stainless steel be welded?
Yes. 304, 304L, 316, 316L, and duplex grades weld well via TIG or MIG. "L" grades (low carbon) avoid carbide precipitation at weld HAZ. 17-4 PH welds but requires post-weld heat treatment. We follow AWS D1.6 weld procedures with qualified welders.
Do you provide passivation certificates?
Yes. Passivation per ASTM A967 with copper sulfate test (or equivalent verification) is documented on the certificate of conformance. For medical and pharmaceutical customers we provide the full test method, lot number, and results.
Why is 17-4 PH more expensive than 304?
17-4 PH is precipitation-hardenable, achieving yield strengths 5× that of 304 (1,100 MPa vs 205 MPa). Raw material cost is higher (roughly 1.5× 304), and heat treatment adds processing steps. Specify 17-4 PH only when strength is the driving requirement.
Is stainless magnetic?
It depends on the grade and condition. Austenitic grades (304, 316L) are non-magnetic in the annealed state but can become weakly magnetic after cold working or welding. Ferritic (430) and martensitic (17-4 PH in some tempers) are magnetic. For MRI-safe parts, specify annealed 316L.
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