Page 113 - SSAB Welding Handbook Edition 2

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Welding handbook 19.0 Stud arc welding

The dimensions of the ferrule are selected in order 19.5 Objectives related to short
to provide a good fit between the stud and the shape cycle welding
©SSAB
of the parent metal. One example is shown in
fig. 19.4. A small drawback to the use of a ferrule is The short cycle method enables welding of small
that they need to be removed after each stud weld studs. This method is performed with a higher
and each ferrule can only be used once. current and lower arc times compared to welding
with the other stud arc methods mentioned. The
penetration depth of the weld metal in the short cycle
method is shallower in relation to the other stated
methods. Welding without shielding gas will simplify
the performance. Nevertheless, this alternative can
lead to a larger degree of oxidation of the molten
weld metal, which can cause lowered mechanical
properties in the joint. Additionally, the level of
Fig. 19.4: A ferrule. spatter may increase. However, when there are mild
(Reproduced by permission, Areg Bultsvetsspecialisten AB) requirements regarding the properties of the joint, this
kind of short cycle process may be the best option for
welding small studs.
19.4 The objective of the shielding gas
When welding studs with diameters of 6 mm and
A shielding gas protection around the stud can be above it is always recommended to apply a shielding
used as an alternative to a ferrule. However, this gas in order to avoid pore formation in the weld
alternative is used to a lesser extent compared to metal.
welding with a ferrule.

The function of shielding gas is relatively similar to 19.6 The welding performance
a ferrule, namely to:
4 Protect the molten weld metal from reacting with Drawn arc stud- and short cycle welding are
the surrounding air during welding. performed with high levels of current. The amperage
is raised as the size of the stud increases. The
4 Shape the cap and the penetration profile of the maximum value depends on the capacity of the
weld metal.
welding equipment. The current level can be up to
4 Counteract pore formation in the weld metal. approximately 2500A during the drawn arc process
for studs of Ø 30 mm.
The drawn arc methods must always be performed
with a ferrule or a shielding gas protection of the The feasible welding parameters depend on the
weld pool. One suitable shielding gas composition welding equipment and the welding situation.
for all types of studs is 82% Ar+18% CO . The gas
2 Manufacturers of stud arc welding equipment, for
shielding flow in both drawn arc stud welding and instance, can provide approximate values for certain
short cycle welding is typically set to 5-6 l/min for situations. These values may need to be fine tuned
Ar/CO mixtures. for the particular welding situation.
2

The typical penetration depth of the weld metal is
usually in the range of 1-3 mm for the stud arc
welding processes in this chapter.

This handbook contains general suggestions and information without any expressed or implied warranty of any kind. SSAB hereby expressly disclaims
all liability of any kind, including any damages, in connection with the use of the information and for their suitability for individual applications. 113
It is the responsibility of the user of this brochure to adapt the recommendations contained therein to the requirements of individual applications.