Page 112 - SSAB Welding Handbook Edition 2

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19.0 Stud arc welding Welding handbook

Stud arc welding of high strength steels, such as particular stud arc welding process, see fig. 19.3.
Hardox and Strenx, is performed with a negative The manufacturers of studs can provide further
©SSAB
polarity of the electrode and a positive polarity of recommendations on this matter.
the work piece.

The welding performance can either be hand held
or executed in stationary fixed equipment in
production environments.

The actual welding time for a stud is normally up to:
4 2 seconds for drawn arc stud welding with
ceramic ferrule. Fig. 19.3: The stud to the left is suitable for the drawn arc stud welding
with ceramic ferrule or shielding gas. The stud to the right has a wide
4 1 second for drawn arc stud welding with flange, which makes it appropriate to short cycle welding.
shielding gas. (Reproduced by permission, Areg Bultsvetsspecialisten AB)
4 0.1 second for short cycle welding.
Unalloyed, low alloyed and stainless studs can be
used. Unalloyed and low-alloyed studs of material
19.2 Studs group 4.8 in ISO 898-1 and stainless studs according
to group A4 in the standard ISO 3506-1 have been
The geometry of the stud is most commonly a solid
cylindrical shape, although other shapes can be evaluated and found suitable for welding of the
applied. Hardox and Strenx grades. Studs of other classes
may be appropriate as well, but it is up to the user
to evaluate their applicability.
Drawn arc stud welding techniques with a ferrule
or shielding gas can weld studs in the range of
approximately Ø 6-30 mm. In these cases, the
plate thickness needs to be at least ¼*diameter of 19.3 The objective of the ferrule
the cylindrically shaped stud. Short cycle welding When a ceramic ferrule is applied, it is placed
is designed for welding smaller sized studs of around the stud prior to welding.
approximately Ø 2-12 mm. The minimum plate
thickness for this method is 1/8*diameter of the Its primary functions are to:
cylindrically shaped stud. The suppliers of studs 4 Isolate and focus the heat generated from the
and stud arc welding equipment can provide the welding process to the weld pool.
requirements for other stud dimensions and 4 Counteract chemical reactions between the melt
geometries.
and the surrounding air to promote beneficial
mechanical properties in the weld metal.
The studs are especially designed for welding. Only
one side of the stud can be welded to the steel 4 Form the cap of the weld metal.
structure. The weldable side has a contact tip in the 4 Prevent formation of pores in the weld metal.
center part of the cross section that facilitates a This is done through small vents in the lower
symmetrical and completely penetrated joint. When part of the ferrule that allow gases to flow from
using a ferrule, the contact tip will typically include an the weld metal while at the same time prevent
aluminum flux. The purpose of the flux is to enhance surrounding air from reaching the liquid melt
and stabilize the arc formation during welding. When during welding.
welding without a ferrule, the contact tip is normally 4 Protect the welding operator from spatter while
made of the same material as the rest of the stud. The welding.
exact shape of the stud may be optimized to suit a

112 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.
It is the responsibility of the user of this brochure to adapt the recommendations contained therein to the requirements of individual applications.