This
article will cover some welding defects that are sometimes overlooked or not
considered. Each welding project requires careful considerations. They include:
- The process, the type of welding i.e. stick, MIG, TIG.
- The composition of the base metal and thickness.
- The welding position, i. e. flat, vertical, horizontal, overhead.
- The weld joint and type.
- Electrical supply and equipment.
- And finally, the welding techniques to be used.
Welding Defect Rememdies
To
minimize the chance of welding defects be sure to consider 1) the travel speed
of the pass; 2) the size and type electrode; 3) machine settings; 4) make sure
the welding is done in accordance with the plan and the current conditions.
Most
of, or a great deal of, welding defects can be identified by the “naked eye.”
By knowing what is likely to produce welding defects you will learn how to avoid
them. Production without defects saves time, materials, repair costs, and a decrease
in productivity.
The
two following causes for weld rejection should not be but are often overlooked
1) is the weldor proficient with the process being used? 2) is the welding rod
supply up to standards? One remedy to welding defects is to use only properly stored, dried, and maintained welding
rods. (Check out our entire inventory of Welding Rod Ovens.)
Welding
defects include poor penetration. It’s the failure of the welding rod and base
metal to fuse together. It’s caused by a root face that is too big; a root opening
that is too small; an electrode that’s too large; slow travel speed or a machine
setting that’s too low.
Poor
fusion is the failure to blend the layers of weld metal together with the base
metal. A lack of fusion is caused by ” . . . failure to raise to the melting
point of the base metal or the deposited weld metal,” (Miller Electric Mfg.
Co.) It’s caused by improper fluxing; dirty plate surfaces; improper electrode
size or type; wrong current settings. Electrodes that do not meet the storing,
drying and maintenance specifications also cause it.
Undercutting
is another problem that causes welding defects. It burns away the base metal
at the toe of the weld. It’s caused by a current adjustment that is too high;
an arc gap that is too long or failure to fill up the crater completely with weld
metal.
Porosity
looks “sponge like,” or like tiny “bubbles” in the weld. It’s
caused by gases being released by the cooling weld because a current setting is
too high or arc is too long.
Slag
inclusion occurs when the slag is not chipped and cleaned properly and then another
pass is made over the top. To avoid, 1) prepare the groove and weld properly before
each pass; 2) thoroughly clean in between passes; check the machine settings against
those suggested by the manufacturer; 3) hold a smaller weld puddle.
Learn
more about proper welding techniques.