1.4571 VS 1.4404 Stainless Steel: The Difference?

What is the difference between stainless steel grades 1.4404 (316L) and 1.4571 (316Ti)? Check out the analysis below, which highlights some of the key pros and cons of both material grades.

While EN 10088 defines a minimum titanium content of five times the carbon content for 1.4571, ASTM A240 requires that the titanium content of the 316Ti grade must be at least five times the sum of the carbon and nitrogen contents.
Therefore, according to ASTM, 316Ti is always 1.4571, but 1.4571 is not necessarily 316Ti, as the minimum chemical requirements are not sufficient.

The corrosion behavior of both grades, 1.4571 and 1.4404, is generally very similar. Just a few substantial differences need to be mentioned:
Titanium-stabilized 1.4571 has a higher sensitivity to pitting corrosion, and therefore the same grade is less consistent in its resistance to (chloride-induced) stress corrosion cracking, and titanium-stabilized 1.4571 has a lower stability against intergranular corrosion, for other corrosive attacks the two grades behave almost identically.

Mechanical properties of 1.4571 and 1.4404 stainless steels
Alloying with titanium leads to an increase in the maximum application temperature. The heat resistance of 1.4571 is up to 400 degrees Celsius. For 1.4404 it lies between 300 and 350 degrees Celsius.
Compared to 1.4404, titanium enrichment reduces the performance in terms of other mechanical properties such as cold formability, cold compressibility and notched impact strength. This is why 1.4404 is often the material of choice for cryogenic liquids.

Machinability of 1.4571 and 1.4404 stainless steels
Machinability: Neither the grades 1.4404 nor 1.4571 are typical stainless steel grades suitable for machining.
For 1.4571, an additional negative must be mentioned: Titanium carbides are very hard and therefore lead to higher tooling costs and slower machining speeds.
Mirror polishability: In theory, carbides can lead to black titanium lines, which would impair mechanical surface finishing.
Purity level: By definition, the presence of titanium carbides reduces the purity of the material. This is not the case for 1.4404, as there is no titanium.