©
COPYRIGHT 2000 THE ESAB GROUP, INC. LESSON
V APPENDIX
A
LESSON
V -
GLOSSARY OF
TERMS Austenite
- High temperature
crystal structure of carbon steel or the room temperature
structure of chrome-nickel steel. Martensite
- The hard phase
that develops on rapid cooling of carbon and low alloy
steels. Ferrite
- The normal
crystal structure of low carbon steel at room tempera- ture.
Transition Temperature
- The temperature
at which the crystal structure of steel changes, usually
in the range of 1500-1600°F. Carbide
Precipitation - The
formation of chromium carbide in austenitic stainless steel
that allows intergranular corrosion
in corrosive service. Ferrite
in Austenitic Stainless
Steel - The
magnetic finely dispersed crystal structure in austenitic steels
that causes the austenite grains to
become smaller and crack resistant.
Ferrite Number
- Ferrite Numbers
(FN) are the current industry accepted figures for
specifying ferrite content in austenitic stainless steel weld metal,
as approved by the Welding Research
Council (WRC), American Welding
Society (AWS) and other organizations. Adopted dur-
ing the 1970's, "ferrite
number" is not to be confused with "Per-
cent Ferrite" that
is still used in some cases. Metallurgically
Similar
Steels - Multiple
steel compositions that have essentially the same crystal
structure, such as austenite or ferrite.
Preheat - The
heating of the parts of a structure to be welded before weld-
ing is started.
