Welding Skills Chapter 42
What are 2 common applications for magnesium and why?
Aerospace components and auto racing parts because of it's high strength to weight ratio
What shielding gas is typically used to weld aluminum and why?
Argon-helium for maximum penetration must most of the time argon
What are the major factors the affect the weld-ability of aluminum?
Cleanliness of the weld area, ability to heat treat, and desired appearance after welding
What are 2 categories of aluminum?
Heat-treatable and non heat-treatable
How does the welding of non heat-treatable alloys effect the HAZ?
It causes a loss of strength in the HAZ
What must the oxide film on aluminum be removed?
It melts at 3X the melting temperature of the base metal and will prevent molten aluminum from fusing properly
Why is AC current used to weld aluminum?
It removes oxide film by breaking it apart during the cycle when the electrode is positive
What problems can titanium oxide cause if not removed before welding?
It will cause problems with fusion, contamination of the weld, and weld bead embrittlement
What is most important for welding nickel alloys?
Joint cleanliness, because they will crack from contamination
what types of applications is nickel typically used?
Nickel alloys are used for: high-temp strength and extreme corrosion resistance
What are two means by which non ferrous metals are strengthened?
Strain hardening (work hardening) and precipitation hardening (age hardening)
Why does aluminum require more heat input than steel?
aluminum conducts heat 3-5 times faster than steel, more heat is needed to compensate for the rapid cooling
Why are jigs in fixtures require for welding copper?
because of it's very high coefficient of thermal expansion