Page 115 - SSAB Welding Handbook Edition 2

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Welding handbook 19.0 Stud arc welding

equipped with a pre-current function that can
remove primer and foreign substances like mill scale Maximum recommended preheat temperature
©SSAB
and mild rust prior to welding. Favorable weld
quality can be attained by welding directly on Strenx 700 300°C
primed plates, although there may be an increased Strenx 900 300°C
tendency toward porosity in the weld metal Strenx 960 300°C
compared to welding on a bare steel surface. Strenx 1100 200°C
Strenx 1300 200°C
Hardox HiTemp 300°C
19.8 Preheating Hardox HiTuf 300°C
Hardox 400 225°C
Stud arc welding demands a lesser degree of
preheating to prevent hydrogen cracks in the joint Hardox 450 225°C
compared to the MAG, MMA, SAW and TIG Hardox 500 225°C
methods. If hydrogen cracks appear, they are Hardox 500Tuf 225°C
typically embedded in the HAZ. If present, a Hardox 550 225°C
reduced torque resistance can reveal these cracks. Hardox 600 225°C
The fractures, in these cases, are situated in the Hardox Extreme 100°C
parent metal near the stud.

SSAB suggests preheat levels for the Hardox and Tab. 19.2: Maximum preheat temperatures.
Strenx grades based on in-house evaluations.
However, these values are approximate due to the
variations of parameters that are possible during The preheating process
welding. The stated preheat temperatures cover The preheating process is the same as for other types
welding with unalloyed and low-alloyed studs from of welding, see fig. 19.6.
material group 4.8 in ISO 898-1 and stainless stud
consumables according to group A4 in the standard Measure the preheat
ISO 3506-1. Suitable categories of studs are temperature here
according to table 19.1.
75 mm

Steel grade Type of stud Min. preheat
temperature
All Strenx and Hardox Unalloyed, low-alloyed Room
grades except Hardox and stainless studs temperature
500, Hardox 500 Tuf, Location for stud welding
Hardox 550, Hardox
600 and Hardox Fig. 19.6: Preheating. A holding period of at least 2 min/25 mm of
Extreme
the plate thickness in the joint is needed prior to welding for even
Hardox 500 Tuf, Only stainless studs 100 heat distribution throughout the plate thickness
Hardox 500,
Hardox 550
Hardox 600, Only stainless studs 150
Hardox Extreme

Tab. 19.1: Appropriate stud categories.

The maximum preheat levels in order to achieve
beneficial mechanical properties in the joint are
specified in table 19.2.

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. 115
It is the responsibility of the user of this brochure to adapt the recommendations contained therein to the requirements of individual applications.