©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
III
3.5 ACID
AND BASIC SLAG SYSTEMS The
type of slag produced from covered electrodes has a definite effect on the quality
of the weld metal.
The E6010, 6011, 6012, 6013, 7014, 7024 and other cellulosic and rutile
elec- trodes,
produce slags that are predominantly silicon dioxide (sand) and have an acidic
behav- ior. Acid
slag systems do no refining of the weld metal. In contrast, the slag from
the E7016, E7018
and other low hydrogen electrodes is made up mostly of lime and fluorspar,two
items that are
basic in chemical behavior. Basic slags do some refining of the weld metal,
resulting in lower
nonmetallic inclusion content. 3.6 ADVANTAGES
AND DISADVANTAGES OF MILD STEEL
COVERED ELECTRODES
Of all the welding done in the United
States, approximately half of it is done with covered electrodes
via the shielded metal arc welding (SMAW) process. Every imaginable shape
and structure
made of medium or low carbon steel has been welded with mild steel covered elec-
trodes. The welding advantages
of this process are several. It is the simplest welding pro-
cess available. All that is needed
is a constant current power source, two electrical leads and
the electrode. It is the most
flexible welding process in that it can be used in any position on
almost any thickness of carbon steel
in any location. The disadvantages are that the covered
mild steel welding has lower deposition
rates than other processes, thus making it less effi- cient.
Also, the use of covered mild steel electrodes requires more welder training
than the semi-automatic
and automatic welding processes.
