Page 3 - SA 304

PROCESSING Chemistry of SA 304 as well as microstructure may be modified for special
purpose i.e. for example low magnetic permeability (extra low ferrite).

Hot forming
Hot forming should be carried out in a temperature range of 1150-750° C (2102-
1652°F).

Due to the low thermal conductivity, the holding time of temperature may be
longer
( 50%) than for C.Mn steels. The quenching may be faster after forming.
The cleanliness of the surface is very important (avoid oil contamination). A
neutral or slightly oxidizing atmosphere is required.
Cold forming
The alloy can be cold formed without any problem. The cold hardening behaviour
of the steel explains why it may require more powerfull equipments than for a

structural steel.
Pickling
A nitro-hydrofluoric acid bath (10-20% HNO 3 – 1,5-5% HF) at 20-60°C ( 68-142°F)
is used for the pickling treatment.
A 10-20% H 2 S0 4 – 1,5-5% HF pickling bath may also be used. Passivation-
decontamination treatments may be performed with a 10-20% weight nitric acid
solution.

Cutting
 Thermal cutting (plasma, thermal sawing…). After cutting pickling or grinding are
necessary to eliminate the oxide formed layer.
 Mechanical cutting (shearing, stamping, cold sawing…)
Welding
The alloy can be easy welded without hot cracking phenomenon, using an
adequate filler metal (from 5 to 15%  ferrite).

The alloy is not sensitive to cold cracking phenomenon. All welding processes can
be used including filler processes.
Filler material
 Electrode E308L-15 or E308L-16 (ASME Sect II - Part C SFA5-4)
ER 308L or ER 308L Si (ASME Sect II - Part C SFA 5-9)
 Wire

A post-weld heat treatment is not necessary.
Preheating and post heating are not necessary.
200°C (392°F) is the maximum interpass temperature. Post-weld pickling and
passivation treatment are necessary.

MACHINING Due to its cold work hardening, the alloy is less machinable than a 13% Cr
martensitic stainless steel.