What is the difference between S31600 and S31603 stainless steel?

Differences Between S31600 and S31603 Stainless Steels

1. Standards and Designations

S31600

ASTM/AISI 316 stainless steel (UNS number: S31600), a medium-carbon austenitic stainless steel.

JIS SUS316 (Japan), KS STS316 (Korea), EN 1.4401 (Europe, with minor compositional variations but similar properties).

S31603

ASTM/AISI 316L stainless steel (UNS number: S31603), an ultra-low carbon (L-grade) austenitic stainless steel.

JIS SUS316L (Japan), EN 1.4404 (Europe).

 

S31600 and S31603 Stainless Steels Chemical Composition 

	S31600 (316)	S31603 (316L)
	Less than or equal to 0.08%	Less than or equal to 0.03%
	16.0–18.0%	16.0–18.0%
	10.0–14.0%	10.0–14.0%
	2.0–3.0%	2.0–3.0%

S31600 and S31603 Stainless Steels Mechanical Properties

	S31600 (316)	S31603 (316L)
	Greater than or equal to 515 MPa	Greater than or equal to 485 MPa
	Greater than or equal to 205 MPa	Greater than or equal to 170 MPa
	Greater than or equal to 40%	Greater than or equal to 40%
High-Temperature Strength	Slightly better than S31603	Slightly lower but better high-temperature toughness
		No post-weld heat treatment needed; excellent intergranular corrosion resistance

 

S31600 and S31603 Stainless SteelsCorrosion Resistance

S31600: Higher carbon content ( Less than or equal to 0.08%) may cause chromium depletion at grain boundaries (due to Cr₂₃C₆ precipitation) when exposed to 400–850 degree (sensitization temperature range), leading to intergranular corrosion.

S31603: Ultra-low carbon ( Less than or equal to 0.03%) virtually eliminates Cr₂₃C₆ formation, providing inherent resistance to intergranular corrosion even without post-weld treatment, ideal for welded structures.

equal resistance to chloride-induced pitting/crevice corrosion (due to identical Mo content), superior to 304 stainless steel.

S31600 has slightly better high-temperature oxidation resistance (above 870 degree ) due to minor carbon effects, though the difference is negligible in most applications.