Stainless steel :
and precipitation hardening stainless steels
These steels generally contain 12 to 19% chromium, and their carbon content
varies from 0.08 to 1.2%.
They may contain nickel and molybdenum as well as certain alloy additions such
as copper, titanium or vanadium.
These steels combine good corrosion resistance with mechanical properties
equivalent to those of top-of-the-range non-stainless steel alloys. These
properties are obtained following the appropriate heat treatment: quenching and
tempering for martensitic steels, quenching and ageing and/or thermomechanical
treatment for precipitation hardening steels.
- Martensitic steels: 1.4021 (or X20Cr13) ; 1.4034 (or X46Cr13) ; 1.4029 (or
- Precipitation hardening steels : 1.4542 (or X5CrNiCuNb16-4) ; 1.4568 (or
These are Iron-Chromium or Iron-Chromium- Molybdenum alloys whose chromium
content varies from 10.5 to 28% and whose carbon content does not exceed 0.08%.
These steels generally contain no nickel.
They are ferromagnetic, and contrary to popular belief, the fact that this
steel family is ferromagnetic by no means implies poor corrosion resistance!
Certain ferritic grades have corrosion-resistant properties that are comparable
or even superior to those of the most common austenitic steels.
Ex : 1.4016 (or X6Cr17) - 1.4113 (or X6CrMo17- 1) - 1.4510 (or X3CrTi17)
These stainless steels are by far the most wellknown and widely used: in
addition to a minimum chromium content of roughly 17%, they contain nickel
(usually 7% and more) and possibly additions of molybdenum, titanium, niobium,
Their tensile Mechanical properties are usually average, but for certain grades
can be considerably improved through cold hardening.
On the other hand they are highly recommended for cryogenic applications, due
to their lack of fragility at low temperatures.
Ex : 1.4307 (or X2CrNi18-9) - 1.4404 (or X2CrNiMo17-12-2)
These steels are characterised by high chromium contents (22% and more) and
relatively low nickel contents (3.5 to 8%). A special feature of these steels
is their dualphase structure (austenite + ferrite) at ambient temperature, and
their austenite content ranges from 40 to 60% depending on the grade. They are
also called "duplex" steels.
Their tensile Mechanical properties are higher than those of the austenitic
steels (approximately 1.2 times for tensile strength and 2 times for yield
strength). They can also be cold hardened.
Their corrosion resistance is generally higher than that of austenitic steels,
especially in respect of generalised corrosion and stress corrosion.
Ex : 1.4462 (or X2CrNiMoN22-5-3)
Although all stainless steels can cover a certain range of high temperatures,
depending on their composition, the term "refractory" is often used for highly
alloyed grades suitable for working temperatures between 900 and 1150°C
(Standard EN 10095).
Ex : 1.4841 (or X18 CrNiSi 25-21) - 1.4845 (or X8 CrNi 25-21)