voestalpine Bohler Welding URANOS 2000 SMC Mode D'emploi page 40

OPERATING INSTRUCTIONS
EN
Characteristics of TIG welds
The TIG procedure is very effective for welding both carbon and alloyed steel, for first runs on pipes and for welding where good
appearance is important.
Straight polarity is required (D.C.S.P.).
Preparing the edges
Careful cleaning and preparation of the edges are required.
Choosing and preparing the electrode
You are advised to use thorium tungsten electrodes (2% thorium-red coloured) or alternatively cerium or lanthanum electrodes
with the following diameters:
(DC-)
3-20 A
15-80 A
70-150 A
150-250 A
250-400 A
400-500 A
500-750 A
750-1100 A
The electrode must be sharpened as shown in the figure.
Filler metal
The filler rods must have mechanical characteristics comparable to those of the parent metal.
Do not use strips obtained from the parent metal, since they may contain working impurities that can negatively affect the
quality of the welds.
D.C.S.P.-Pulsed (Direct Current Straight Polarity Pulsed)
welding pool width and depth.
The welding pool is formed by the peak pulses (Ip), while the base current (Ib) keeps the arc
and consequently a reduced risk of hot cracks and gas inclusion.
Increasing the frequency (MF) the arc becomes narrower, more concentrated, more stable and
the quality of welding on thin sheets is further increased.
Current range
(DC+)
-
-
10-20 A
15-30 A
25-40 A
40-55 A
55-80 A
80-125 A
(AC)
3-20 A 0,5 mm
20-30 A 1,0 mm
30-80 A 1,6 mm
60-130 A 2,4 mm
100-180 A 3,2 mm
160-240 A 4,0 mm
190-300 A 4,8 mm
325-450 A 6,4 mm
40
Electrode
Ø
30°
30-60°
60-90°
90-120°
120-150°
150-180°
150-180°
150-180°