Corrosion handbook

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TERMS V2A AND V4A – DESIGNATION ACCORDING TO
ENISO 3506-1:2009
Description
The terms V2A and V4A date back more than 100 years and have their origin
in the designation of the first trial productions of stainless steel. The V stands
for “Versuch”, which is German for “test or trial”, and the A for “austenite”.
V2A denotes a Cr/Ni alloy and V4A a CrNiMo alloy. The terms are still used as
synonyms for stainless steel in some countries.
The EN ISO 3506-1:2009 standard (mechanical properties of corrosion-resistant
stainless steel fasteners, bolts, screws and studs) uses designations ranging
from A1 to A5 for austenitic stainless steel. This range is based on the alloy
composition and does not fully reflect corrosion behavior. For example, the grade
1.4401 is in the A4 group and 1.4571 is in the A5 group. However, both stainless
steel alloys exhibit practically the same corrosion resistance.
Often the terms A2 and A4 are used to talk about a group of stainless steel grades
with certain corrosion resistance. However, this is not completely accurate, since
specific information about the alloy composition and thus also some properties
such as weldability cannot be deduced from these terms.