1.4404 vs 1.4571 Stainless Steel: Corrosion Resistance Compared

Two Austenitic Grades Compared

1.4404 (X2CrNiMo17-12-2), known as AISI 316L, and 1.4571 (X6CrNiMoTi17-12-2), known as AISI 316Ti, are both molybdenum-bearing austenitic stainless steels. They share similar chromium, nickel and molybdenum levels and are supplied under EN 10088-2 and EN 10088-3 for flat and long products respectively. The essential difference lies in the way each grade handles carbon: 316L keeps carbon very low, while 316Ti adds titanium to stabilise the carbon that remains.

Chemical Composition Comparison

Element (%)	1.4404 (316L)	1.4571 (316Ti)
Carbon (C)	≤ 0.030	≤ 0.08
Silicon (Si)	≤ 1.00	≤ 1.00
Manganese (Mn)	≤ 2.00	≤ 2.00
Phosphorus (P)	≤ 0.045	≤ 0.045
Sulfur (S)	≤ 0.030	≤ 0.030
Chromium (Cr)	16.5 - 18.5	16.5 - 18.5
Nickel (Ni)	10.0 - 13.0	10.5 - 13.5
Molybdenum (Mo)	2.0 - 2.5	2.0 - 2.5
Nitrogen (N)	≤ 0.10	≤ 0.10
Titanium (Ti)	-	≥ 5 × C and ≤ 0.70

Because titanium is held in stable titanium carbide, 316Ti tolerates a higher carbon content without risking chromium carbide precipitation. Grade 316L reaches the same freedom from sensitisation by keeping carbon at or below 0.03%.

Corrosion Resistance in Service

Condition	1.4404 (316L)	1.4571 (316Ti)
Intergranular corrosion after welding	Very low carbon prevents carbide precipitation; excellent without post-weld annealing	Titanium stabilises carbon, giving reliable resistance even at elevated temperature
Pitting and crevice corrosion	Molybdenum raises resistance well above 304L	Similar performance, since molybdenum levels match
Chloride media and seawater	Better than 304, though concentration and temperature still govern	Comparable, with a slight edge in long-term hot or pressurised service
Continuous high temperature	Carbide precipitation becomes possible above roughly 400 °C	Titanium addition keeps the structure stable over long exposures

Since both grades carry the same chromium and molybdenum ranges, their pitting resistance equivalent numbers (PREN, calculated as Cr + 3.3 Mo + 16 N) fall in the same band, around 25 to 26 from mid-range analysis. The practical difference therefore appears in welded and high-temperature service rather than in general chloride exposure.

Choosing Between Them

Choose 1.4404 for the majority of welded process equipment, tanks, pipework, heat exchangers and hygienic plant, where the extra ductility of the low-carbon grade and the wide availability of matching filler metals simplify fabrication.

Choose 1.4571 where service temperature remains high for long periods, or where repeated thermal cycling makes stabilisation attractive, as with certain heat exchanger and furnace-adjacent components.

Consider availability and cost: 316L is the more widely stocked grade in plate, sheet, bar and tube, which usually shortens lead times.

Check the specification: some end users write a specific grade into the design code, and substitution then requires documented approval.

Fabrication Notes

Both grades are welded by TIG, MIG and plasma processes with low-carbon or stabilised matching fillers, and neither requires post-weld heat treatment for corrosion protection in normal thicknesses. Titanium-stabilised material is slightly less suited to bright annealing and mirror polishing because titanium-bearing inclusions can affect the surface. Formability and machinability are similar, though 316L generally shows better ductility for deep drawing.

Frequently Asked Questions

Q: Is 1.4571 better than 1.4404?
Neither is universally better. 316L is preferred for welded and hygienic work because of its low carbon and ductility, while 316Ti has the advantage in long-term high-temperature service.

Q: Can 1.4404 and 1.4571 be welded to each other?
Yes. Both are austenitic grades with matching chromium, nickel and molybdenum levels, so a low-carbon 316L type filler is suitable and no post-weld anneal is normally needed.

Q: Do the two grades have the same corrosion resistance in seawater?
Very similar, because their chromium and molybdenum contents match. Temperature, chloride concentration and oxygen level matter more than the choice between them.

Q: What does the titanium do in 1.4571?
It combines with carbon to form stable titanium carbides, so chromium stays in solution and the steel resists intergranular corrosion at high temperature or after welding.

Q: Which grade is more common in industry?
1.4404 (316L) is the more widely used and stocked grade across plate, sheet, bar and tube, and is often the default chloride-resistant austenitic choice.

Q: Are the mechanical properties different?
They are close. Both are supplied annealed with tensile strength around 500 - 700 MPa and 0.2% yield strength at or above 190 MPa in typical product forms.