LESSON VII
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COPYRIGHT 2000 THE ESAB GROUP, INC. Turn
Pages APPENDIX
A LESSON VII -
GLOSSARY OF TERMS Chemical
symbols for the alloying elements commonly used in welding metallurgy:
C -
Carbon S
- Sulfur
Mn -
Manganese B
- Boron
Si -
Silicon Al
- Aluminum
Cr -
Chromium Cb
- Columbium
(Niobium) Ni
- Nickel
Ti -
Titanium Mo
- Molybdenum
W -
Tungsten V
- Vanadium
Co -
Cobalt Cu
- Copper
Pb -
Lead P
- Phosphorus
N -
Nitrogen Flux
Voids - Section
of a flux cored electrode which contains no flux. Voids can
cause serious problems, especially
in low alloy types. Mill
Scale - The
iron oxide (FeO) coating normally found on the surface of hot
rolled steels.
-
The temperature to
which many of the low alloy steels must be
heated before welding. Preheating
retards the cooling rate, allowing more
time for the hydrogen to escape, which minimizes underbead
cracking. Preheat temperatures
can vary from 10°F to 500°F on ½” sections
to 300°F to 600°F on heavy sections, depending upon the
alloy.
- The minimum temperature of the weldment
between passes. It is
usually about the same as the preheat temperature. Peening
- The
mechanical working of metal by means of hammer blows to
relieve stresses and reduce distortion.
Peening is recommended for thicker
sections (over 1” or 2”) of some alloys on each successive
pass. Experience has shown that
peening helps to reduce cracking. Peening
may decrease the ductility and impact properties; however,
the next pass will nullify this condition.
For this reason, the last surface
layers should not be peened.
- Reheating the weldment to 1100°F to 1350°F after
welding and
holding at that temperature for a specified length of time. Heat
treating allows additional hydrogen
to escape, lowers the residual stresses
due to welding, and restores toughness in the heat affected
zone.
Preheat
Temperature
Interpass
Temperature
Post
Weld
Heat Treatment
