Terms
The ability of a metal to exist in more than one crystalline form
Allotropy
14 atoms, one in ea. corner of the cube and one in the center of ea. cube face
Face- centered cubic
Curie point of steel.
What is 770C or 1418F
The use of high travel speeds with welding aluminum helps reduce....
Hot cracking
Occurs when cooling iron reaches curie point
What is becomes Magnetic
Heat process to restore uniform grain size in metal and relieve residual stress
Normalizing
9 atoms, one at each corner and one in the center of the cube
Body-centered cubic
Point at which aluminum "oxide" melts
2000-2072C (3760-3762F)
How does aluminum resist atmospheric corrosion
Forms a thin, tough oxide film
Elements in the martensitic stainless steel (400) series are responsible for its hardenable structure
Chromium and Carbon
Purpose is to soften the steel, induce softness, improve machinability and relieve internal stresses.
What is Annealing
What pattern has Greater ductility
FCC
Temperature that carbon and alloy steels should be preheating to prior to welding
200-300C (392-572f)
Aluminum alloy that is particularly prone to hot shortness
6061
Major alloying element in the 5XXX series of aluminum
Magnesium
Steel is heated to it's upper critical temp, and held there just long enough for the center to be fully transformed to austenite then cooled rapidly
What is Quenching
Structural arrangement of iron atoms at room temp.
BCC
Temp pure iron changes to a liquid state
1540c (2804f)
Copper is added to aluminum alloys to....
impart very high strength and machinability
Approximate annealing temp. for aluminum and aluminum alloys
343c (650f)
Achieved by heating above the re crystallization temp. followed by controlled cooling
what is annealing
Gold, aluminum, nickel, lead, silver and copper show this arrangement
FCC
Lower critical temp of carbon steels
721c (1330f)
Major alloying element in the 4XXX series of aluminum
Silicon
Stainless steel that is not transformed to austenite when heated
Ferritic