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Chapter 3: Applications of Common Stainless Steel Alloys
Austenitic Stainless Steel:
EN 1.4301 / AISI 304
The classical, stainless steel (18/8) quality and still the most important steel for manufacturing
anything from kitchen sinks, forks and spoons and dairy and butchery equipment. Ductile, weldable
and fairly corrosion resistant in most normal media. However, the resistance in chloride containing
environments (in particular at elevated temperatures) is frequently inadequate. Due to chlorides,
4301 should not be used for outdoors purposes. It is better suited for indoors use. At temperatures
above 60 ºC (and sometimes even below), SCC is a significant risk (Chapter 4). Upgrading to the
even more corrosion resistant 4404 (“acid resistant”) will solve most corrosion problems; otherwise,
even higher alloyed steel types must be considered.
EN 1.4305 / AISI 303
Sulphur alloyed 4301 possessing excellent properties for cutting, milling and so due to the formation
of MnS (Chapter 2). Only available as rod or wire, and is not good for neither welding nor
pickling. Compared to common 4301, the corrosion resistance of 4305 is inferior in almost any type
of media. Consequently, 4305 should be used with care.
EN 1.4306 / AISI 304L
Low-carbon edition of 4301. C ≤ 0,03 % due to the risk of sensitization and subsequent intergranular
corrosion (Chapter 2 + 4). The theoretical disadvantage is a marginally lower mechanical strength.
The nickel content of 4306 is quite high (10-12 %), and the steel is therefore slightly “over-austenitic”
making it less prone to deformation hardening. This, in turn, makes the 4306 useful for stretchforming.
However, the increased nickel makes 4306 quite expensive and hard to get.
EN 1.4307 / AISI 304L
The standard low-carbon 4301. Identical to 4306; however, with less nickel (8-10,5 % Ni). 4307 is
identical with 4301 with the sole exception that the upper limit of carbon is only 0.03 % instead of
0.07 %, which is preferable when welding, in particular when welding thick goods (Chapter 2 + 4).
Due to the lower Ni, 4307 is cheaper and “less austenitic” than 4306 (10-12 %), and traces of ferrite
or deformation martensite may cause some magnetism, in particular after machining.
EN 1.4310 / AISI 301 / 302
”18/8 classic”. An older edition of the standard 4301 recognizable by comparatively high carbon
content. This increases the mechanical strength of the steel. However, the drawback is a significant
increase in the risk of sensitization and intergranular corrosion. Sometimes used when high-temperature
tensile stress is an issue.
EN 1.4401 / AISI 316
The standard ”acid resistant” steel type. Mechanically much like the ”kid brother” 4301; however,
due to its Mo content (2.0-2.5 %), its corrosion resistance is significantly better in almost every
single environment, regardless if the risk of corrosion is pitting, crevice corrosion or SCC (Chapter 4).
Due to the frequently poor performance of 4301, the 4401 ought to replace 4301 as standard material.
However, because of the high and volatile prices of molybdenum and in particular nickel, the
4401 class is often expensive.
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01.2013