What is the difference between SS304 and SS316?

SS316 contains about 2–3% molybdenum and more nickel, which makes it much more resistant to chlorides and salt water. It costs more, so use it where that resistance is needed.

A low-carbon version (0.03% max) that keeps its corrosion resistance next to welds. It is the usual choice for welded equipment.

Not when annealed; it can become very slightly magnetic after heavy cold work.

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SS316 stainless steel

Also called: AISI 316, 1.4401, X5CrNiMo17-12-2, SUS316, 316L, marine grade stainless

SS316 is an austenitic stainless steel like 304, with about 2–3% molybdenum added. The molybdenum gives much better resistance to salt water, chlorides and many chemicals, so 316 is used for marine, chemical and pharmaceutical equipment.

Quick facts

Type: Austenitic stainless steel with molybdenum
Main alloys: About 17% chromium, 12% nickel, 2.5% molybdenum
Tensile strength: About 515 MPa min (annealed)
Yield strength: About 205 MPa min (annealed)
Corrosion resistance: Better than 304, especially against chlorides
Cost: Higher than 304 (nickel and molybdenum)

Equivalent grades

Standard	Closest grade
AISI / ASTM	316 (UNS S31600); low-carbon 316L (S31603)
EN / DIN	1.4401 (X5CrNiMo17-12-2); 316L = 1.4404
IS 6911 (India)	X04Cr17Ni12Mo2
JIS	SUS316

Typical chemical composition

Element	%
Carbon (C)	0.08 max (316L: 0.03 max)
Chromium (Cr)	16.0–18.0
Nickel (Ni)	10.0–14.0
Molybdenum (Mo)	2.0–3.0
Manganese (Mn)	2.0 max

When to choose 316 over 304

Salt water, coastal sites and anything washed with salty water
Chlorides: swimming pools, brine, many cleaning chemicals
Pharmaceutical and chemical process equipment
Pump and valve parts handling corrosive liquids

Machining and welding

Like 304, it work-hardens and machines more slowly than carbon steel. It welds well by TIG and MIG; use 316L for welded equipment so the area next to the weld keeps its corrosion resistance.

Typical uses

Marine fittings and boat parts
Chemical and pharmaceutical vessels and pipework
Pump shafts, impellers and valve parts
Food equipment handling salty or acidic products
Medical and laboratory equipment

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SS304 stainless steel

Questions

What is the difference between SS304 and SS316?: SS316 contains about 2–3% molybdenum and more nickel, which makes it much more resistant to chlorides and salt water. It costs more, so use it where that resistance is needed.
What is SS316L?: A low-carbon version (0.03% max) that keeps its corrosion resistance next to welds. It is the usual choice for welded equipment.
Is SS316 magnetic?: Not when annealed; it can become very slightly magnetic after heavy cold work.

The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 8 October 2026.