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Family 316 – Austenitic with Molybdenum

316 stainless steel, designated in EN as 1.4401, is a 300 series austenitic (chromium-nickel) that differs from its closest relatives by its molybdenum (Mo) content. This element gives the alloy greater resistance to corrosion and high temperatures.


Molybdenum especially improves resistance to pitting corrosion, typical of saline environments or other solutions with the presence of alkaline chlorides. In addition, it gives the alloy greater resistance to acids, being an excellent material for the chemical industry (sulfuric, hydrochloric, acetic, formic, tartaric and acid sulphates).

Heat treatment

AISI 316 and its variants can be subjected to an annealing process in order to reduce its hardness, increase its ductility and the ability to accept deformation in transformation processes. These heat treatments are given at temperatures between 1038ºC and 1049ºC, temperatures similar to those that we submit to our Numepress pressfiting pieces, in order to guarantee optimal pressing during installation.

316L – Low carbon

The 316L variant (EN 1.4404), the most commercialized in Europe, is characterized by its low carbon content (<0.030). This property makes it a good option to be used in stressful situations, since reducing the precipitation of carbides in the welding zone reduces the possibility of galvanic corrosion.

316Ti – EN 1.4571

The addition of titanium to the alloy (≥5 (C + N)), provides stability to the structure, a greater resistance to intragranular corrosion and high temperatures. This stability is achieved by reducing the precipitation of chromium carbides. To do this, the alloy undergoes a heat treatment during which the titanium reacts with the carbon to form titanium carbides, thus depleting the chromium carbides. Thanks to this process, 316Ti can be used for a long period of time at high temperatures in structures of all kinds.