What is the difference between S31803 and SS316?

What is S31803 material standard?

UNS S31803 is a standard, first-generation 22% chromium-containing duplex stainless steel, commonly referred to as Alloy 2205 or DIN 1.4462. Its microstructure consists of a 50/50 austenite-ferrite duplex structure; compared to standard 300-series austenitic stainless steels, it possesses a yield strength approximately double that of the latter, along with exceptional corrosion resistance,particularly regarding resistance to chloride stress corrosion cracking.

 

What is sS 316 grade material?

SS316 (Grade 316) is a premium austenitic stainless steel that, due to its 2% to 3% molybdenum content, exhibits exceptional corrosion resistance-particularly in the presence of chlorides and harsh marine environments. Possessing high tensile strength, excellent durability, and superior high-temperature resistance, it can be fabricated into a wide variety of practical product forms-including plates, coils, tubes, bars, and wires-making it highly suitable for applications in sectors such as the chemical, pharmaceutical, and marine engineering industries.

 

What is the difference between S31803 and SS316?

UNS S31803 (often called 2205) is a duplex stainless steel that offers roughly twice the yield strength and superior corrosion resistance (especially to chlorides and pitting) compared to standard 316/316L austenitic stainless steel. While SS316 is more versatile, easier to form, and generally lower cost, S31803 is ideal for high-strength, highly corrosive environments like marine or chemical processing.

 

Chemical Composition Comparison (Typical Weight %)

Element	SS316 (UNS S31600)	S31803 (Duplex 2205)
Chromium (Cr)	16.0 – 18.0%	21.0 – 23.0%
Nickel (Ni)	10.0 – 14.0%	4.5 – 6.5%
Molybdenum (Mo)	2.0 – 3.0%	2.5 – 3.5%
Nitrogen (N)	≤ 0.10%	0.08 – 0.20%
Carbon (C)	≤ 0.08%	≤ 0.030%
Iron (Fe)	Balance	Balance

 

Mechanical Properties (at Room Temperature)

Property	SS316	S31803 (Duplex)
Yield Strength (0.2% Offset)	≥ 205 MPa	≥ 450 MPa
Tensile Strength (Rm)	≥ 515 MPa	≥ 620 MPa
Elongation (A50mm)	≥ 40%	≥ 25%
Hardness (Rockwell B)	≤ 95 HRB	≤ 31 HRC (approx. 105 HRB)

 

S31803 vs. SS316: Strength

The yield strength of S31803 is approximately 450 MPa; in comparison, the yield strength of 316/316L is about 205 MPa, meaning that S31803 is nearly twice as strong as the latter.

S31803 vs. SS316: Corrosion Resistance

S31803 stainless steel exhibits exceptional resistance to pitting, crevice corrosion, and stress corrosion cracking (SCC), boasting a Pitting Resistance Equivalent Number (PREN) as high as 34. While SS316 offers good corrosion resistance, its performance in high-chloride environments is significantly inferior to that of S31803 (which has a PREN of approximately 25).

S31803 vs. SS316: Cost and Processing

S31803: The cost is typically 20% to 40% higher than that of 316 SS. To ensure that material properties remain uncompromised, its welding processes,including heat input control require much stricter management. SS316 stainless steel is generally more affordable and easier to weld and form.

Temperature Limits: Due to embrittlement effects, S31803 is unsuitable for service environments below -50°C or above 250°C; in contrast, SS316 can be utilized across a much broader temperature range.

 

As a supplier of S31803, Gnee maintains an extensive inventory of popular products for your selection. These materials can be processed into various practical forms,including plates, coils, tubes, bars, and wires,and we offer value-added services such as pipe beveling, custom cutting-to-length, and surface polishing. Every shipment is accompanied by a Material Test Certificate (MTC) compliant with the EN 10204 3.1 standard.
Upon customer request, we can also perform Eddy Current Testing (ET), Ultrasonic Testing (UT), hydrostatic testing, intergranular corrosion testing, and impact testing.

 

S31803 (Duplex Stainless Steel 2205) Specifications

Product Type	Standard	Size Range	Surface Finish
Hot Rolled Plate	ASTM A240	Thickness: 3mm - 100mm; Width: 1500 - 3000mm	No.1, HRAP, Sandblasted
Cold Rolled Sheet	ASTM A240	Thickness: 0.3mm - 6.0mm; Width: 1000 - 1500mm	2B, No.4, BA
Seamless Pipe	ASTM A789 / A790	OD: 6mm - 630mm; WT: 0.5mm - 40mm	Annealed & Pickled (AP)
Welded Pipe	ASTM A789 / A790	OD: 10mm - 2000mm; WT: 0.5mm - 60mm	AP, Polished, Bead Removed
Round Bar	ASTM A276 / A479	Diameter: 5mm - 500mm	Bright, Black, Peeled, Polished
Fittings & Flanges	ASTM A815 / A182	Elbow, Tee, Reducer (1/2" - 48"); Flanges (PN16-PN420)	Machined, Pickled

 

For export orders, we utilize professional anti-corrosion packaging (consisting of waterproof woven bags, wooden crates, and edge protectors) to ensure the materials remain free from contamination during sea transit.