What are the differences between SUS304 and SUS316 stainless steel?

 

 

 

SUS304 and SUS316: Equivalent materials

JIS Grade	AISI/UNS	EN 10088-2	ISO 15510	GB (China)
SUS304	304 / S30400	1.4301	X5CrNi18-10	06Cr19Ni10
SUS316	316 / S31600	1.4401	X5CrNiMo17-12-2	06Cr17Ni12Mo2

 

SUS304 VS. SUS316 stainless steel :Chemical Composition 

JIS G 4304:2021

Grade	C max	Si max	Mn max	P max	S max	Ni	Cr	Mo
SUS304	0.08	1.00	2.00	0.045	0.030	8.00–10.50	18.00–20.00	-
SUS316	0.08	1.00	2.00	0.045	0.030	10.00–14.00	16.00–18.00	2.00–3.00

ASTM A240/A240M-22a

Grade	UNS	C max	Mn max	P max	S max	Si max	Cr	Ni	Mo	N max
304	S30400	0.07	2.00	0.045	0.030	0.75	17.5–19.5	8.0–10.5	-	0.10
316	S31600	0.08	2.00	0.045	0.030	0.75	16.0–18.0	10.0–14.0	2.00–3.00	0.10

 

SUS304 and SUS316 Stainless Steel: Mechanical Properties

Property	SUS304 / S30400	SUS316 / S31600	Unit
Yield Strength (0.2% offset), min	205	205	MPa
Tensile Strength, min	515	515	MPa
Elongation in 50 mm (2 in), min	40	40	%
Hardness, Brinell (HBW), max	201	217	HBW
Hardness, Rockwell B (HRBW), max	92	95	HRBW

 

SUS304 and SUS316 Stainless Steel: Physical Properties

Property	SUS304	SUS316	Unit
Density	7,930	7,980	kg/m³
Modulus of Elasticity (20 °C)	193	193	GPa
Electrical Resistivity (20 °C)	0.72	0.74	μΩ·m
Specific Heat (0–100 °C)	500	500	J/(kg·K)
Thermal Conductivity (100 °C)	16.3	16.3	W/(m·K)
Mean Thermal Expansion (0–100 °C)	17.3 × 10−6	15.9 × 10−6	/K
Melting Range	1,400–1,450	1,375–1,400	°C
Magnetic Permeability (annealed)	< 1.02	< 1.02	μr

 

What is the PREN value difference between SUS304 and SUS316?

PREN (Pitting Resistance Equivalent Number) = %Cr + 3.3 × %Mo + 16 × %N. At nominal compositions, SUS304 has PREN ≈ 18–20, while SUS316 has PREN ≈ 24–26. This means SUS316 offers approximately 30% higher resistance to pitting corrosion than SUS304. For seawater and high-chloride environments (>500 ppm Cl−), SUS316 is the minimum recommended grade.

 

SUS304 and SUS316 Stainless Steel: Stress Corrosion Cracking (SCC)

Both SUS304 and SUS316 are susceptible to chloride stress corrosion cracking (Cl-SCC) at temperatures above approximately 60 °C. Molybdenum does not provide significant protection against SCC-for environments with combined chloride and elevated temperature, duplex stainless steels (e.g., 2205 / S32205) or higher-alloy austenitics (e.g., 904L / N08904, or 6% Mo super-austenitics) should be evaluated.

 

Can SUS304 and SUS316 be used interchangeably?

Not in all applications. For indoor architectural, food-processing equipment, and general industrial environments with low chloride exposure, SUS304 is sufficient and more cost-effective. However, for marine environments, coastal construction, chemical plants, pharmaceutical equipment, and medical devices, SUS316 should be specified. Substituting SUS304 for SUS316 in chloride-rich environments can lead to premature pitting corrosion and component failure within months.

 

Is SUS316 more expensive than SUS304?

Yes, SUS316 typically costs 20–40% more than SUS304 due to its higher nickel content (10.0–14.0% vs 8.0–10.5%) and the addition of molybdenum (2.0–3.0%). Both nickel and molybdenum are costly alloying elements whose prices fluctuate with global commodity markets. However, the total lifecycle cost-including maintenance, replacement, and downtime-often favors SUS316 in corrosive environments where SUS304 would require more frequent replacement.

 

SUS304 and SUS316 Stainless Steel: How to Choose?

Choose SUS304 When:

Indoor architectural applications (handrails, cladding, elevator interiors)

Food and beverage processing equipment (where not exposed to brine or saline solutions)

Domestic kitchenware, sinks, and household appliances

General mechanical parts (fasteners, shafts, brackets) in non-corrosive environments

Automotive trim and exhaust components (non-marine applications)

Choose SUS316 When:

Marine and offshore equipment (deck fittings, heat exchangers with seawater service)

Chemical and petrochemical plants (piping, vessels handling dilute acids)

Pharmaceutical and biotechnology processing equipment (clean-in-place, sterilization)

Pulp and paper bleach plant equipment

 

References

ASTM A240/A240M-22a Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications.
JIS G 4304:2021 Hot-rolled stainless steel plate, sheet and strip.
EN 10088-2:2014 Stainless steels - Part 2: Technical delivery conditions for sheet/plate and strip of corrosion resisting steels for general purposes.
ISO 15510:2014 Stainless steels - Chemical composition. International Organization for Standardization (ISO).
NACE MR0175/ISO 15156 - Petroleum and natural gas industries - Materials for use in H2S-containing environments in oil and gas production.

 

Reliable Stainless Steel Supplier – GNEE

Gnee Stainless Steel (Tianjin) Co., Ltd. is a supplier of stainless steel products with over 18 years of export experience, serving customers in more than 60 countries. Our product range includes:

Stainless Steel Pipes: Seamless (OD 4–219 mm, WT 0.5–20 mm) and Welded (OD 5.0–1219.2 mm, WT 0.5–20 mm)

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