Factors Affecting Seam Shape of Submerged Arc Welding
Submerged arc welding is mainly suitable for flat welding position welding. If certain tooling aids are used, fillet welding and horizontal
welding position welding can also be realized. The main factors affecting the shape and performance of the weld in submerged arc welding
are welding process parameters and process conditions. Below we mainly discuss the situation of the flat welding position.
Influence of welding parameters
The welding process parameters that affect the shape and size of the submerged arc welding seam include welding current, arc voltage,
welding speed and wire diameter.
1. welding current
When other conditions remain unchanged, the effect of increasing the welding current on the weld penetration, whether it is a
Y-shaped groove or an I-shaped groove, under normal welding conditions, the penetration is proportional to the change of the
welding current. The current is small, the penetration depth is shallow, and the excess height and width are insufficient; the
current is too large, the penetration depth is large, and the excess height is too large, which is easy to produce high temperature cracks.
2. arc voltage
The arc voltage is proportional to the arc length. When the arc voltage and welding current are the same, if the selected flux is different
and the electric field strength in the arc space is different, the arc length will be different. If other conditions remain unchanged, the effect
of changing arc voltage on weld shape.
The arc voltage is low, the penetration is large, the width of the weld is narrow, and hot cracks are easy to occur: when the arc voltage is high,
the width of the weld increases, and the excess height is not enough. During submerged arc welding, the arc voltage is adjusted according to
the welding current, that is, a certain welding current must maintain a certain arc length to ensure the stable combustion of the welding arc,
so the variation range of the arc voltage is limited.
3. welding speed
The welding speed has an effect on the penetration depth and width. Usually, the welding speed is small, the welding pool is large, and the
weld penetration and width are both larger. That is, the penetration depth and penetration width are inversely proportional to the welding
speed. The effect of welding speed on the shape of the weld section.
The welding speed is too small, the amount of molten metal is large, and the welding seam is poorly formed: when the welding speed is high,
the amount of molten metal is insufficient, and undercut is easy to occur. In actual welding, in order to improve productivity, the arc power must
be increased while increasing the welding speed to ensure the quality of the weld.
4. wire diameter
When the welding current, arc voltage and welding speed are constant, the shape of the welding seam will change due to the different diameter
of the welding wire.
The effect of current density on the shape and size of the weld, other conditions remain unchanged, the penetration depth is inversely proportional
to the diameter of the welding wire, but this relationship weakens with the increase of the current density, which is due to the increase of the current
density, the molten pool melts the metal With the continuous increase of the amount of molten metal, it is difficult to discharge the molten metal, the
penetration depth increases slowly, and with the increase of the amount of molten metal, the excess height increases and the weld formation becomes
poor. Therefore, the arc voltage should be increased while increasing the welding current during submerged arc welding. Guarantee the quality of
welding seam.