arcweld 130i-ST, Руководство оператора

Страница: 11 / 84

OPERATION CONTROL AND CONECTORS
ARCWELDING DEFECT AND PREVENT METHOD
C-2 C-2
Defect name
Welding seam
doesn’t meet the
requirement
Undercut
Incomplete
penetration
Incomplete
fusiont
Overlap
Crater
Blowhole
Inclusion & slag
inclusion
Hot crack
Cold crack
The groove angle or gap is too small, the
root face is too big.
Welding parameters are not suitable, or
the assembly is not good.
The welder’s operation skill is low.
The welding thermal input is too low.
The arc direction is lean.
There are rust & dust on the side of groove.
The slag between the layers is not cleared
well.
The temperature of molten pool is too
high.
The liquid metal concretes slowly.
The crater time lasts too short.
Over current in the welding of thin plate.
Three reasons will cause cold crack:
The structure turned from the marten site.
The residual stress caused by big restraint
intensity.
The residual hydrogen in welding gap.
In the process of solidification, the inter
crystal segregation is seriously caused. At
the same time, with the effect of welding
stress, the hot crack is formed.
The slag clears bad in the middle layer in
the welding process.
Under current or over speed in the welding.
Welding operation is not proper.
The welding material can not match the
work piece.
The groove design & processing are not
prope.
There are some dust like oil, rust or water
on the work piece surface and groove.
The coating of electrode is damped& is not
drying.
Under current or over speed in the welding.
The arc is too long or lean burning, the
molten pool protection is not good.
Over current, the coating of electrode falls
off and lose protection.
Manipulation of electrode is not proper.
Over current.
Arc length is too long.
The electrode angle is wrong.
Manipulation of electrode is not proper.
The groove angle is not proper.
The root face and assembly gap is not
equal.
Welding technics parameters are
unreasonable.
Choosing the proper groove angle &
assembly gap, improve the assembly quality.
Choosing the proper welding parameters.
Improve the operation skill of welders.
Choosing the proper welding current & speed.
The arc can’t be drawn too long.
The electrode angle should be proper.
Manipulation of electrode should be correct.
Correctly to choose the welding parameters.
Operation seriously.
Enhance the clearness of layers.
In the crater, electrode should be stayed for a
short time or round to manipulate electrode
after the molten pool is filled in by metal, take
to the side for cratert
Strictly control the percentage of S and P in
welding material.
Adjust the structure of welding material.
Adopt the basic electrode.
Adopt low hydrogen type basic electrode.
Bake under the instruction before use.
Remove the feculence before use, reduce the
percentage of hydrogen.
Adopt appropriate parameters and heat input.
After welding, do dehydrogenation at once.
Choosing the electrode of good slag
detachability.
Strictly to clear the slag in the layers.
Correctly to choose the welding parameters.
Adjusting the electrode angle and manipulation
way.
Clear out the dust around groove for about
20~30mm.
Strictly to dry the electrode according to
manual.
Correctly to choose parameters and to operate
Using the short arc operation.
Welding operation in the field should have anti-
wind protection.
Don’t use the invalid electrode.
Choosing parameters based on the welding
different position.
Strictly to control the molten hole size.
Correctly to choose and process the groove
size.
Correctly to assemble and ensure clearance.
Choosing the suitable welding current & speed.
Improve the operation skill of welders.
Caused reasons Prevent methods