Explanations: Welding Flashcards
What type of gas is used in GTA welding to keep oxygen away from the puddle of molten metal, and why?
A stream of helium or argon, to prevent the formation of oxides in the puddle?
What is an oxide?
chemical compounds with one or more oxygen atoms combined with another element.
How does one return the welded section of a heat-treated magnesium part to its original strength?
the entire part must be heat treated again.
How are magnesium and aluminum welding similar?
The same equipment can be used and the joint design also follow similar practices.
Apart from a neutral flame, what type of flame may be used for silver soldering?
A very slight excess of acetylene may sometimes be used, but it must be soft, not harsh.
Why must the the base of the metal first be cleaned of oxides before silver soldering?
a film of oxide on the metal will prevent the silver solder from coming into intimate contact with the base metal.
What is a rosette weld?
A process that fuses two metals together by making a weld inside small circular holes.
Why is welding over a brazed or soldered joint not permitted?
because the brazing and soldering materials will enter the pores of the metal. These materials will weaken the welded joint.
What purpose does the solder provide?
it provides a low-resistance connection, but it should not be depended upon for mechanical strength.
What is tinning?
When resurfacing a soldering iron, all of the pits are filled out and the tip is shaped as desired. The iron is heated and immediately the entire surface is coated with solder to prevent the formation of oxides on the copper. This process is called tinning.
Oxides on the tip prevent the transfer of heat from the copper to the metal being soldered.
What determines the temperature of a welding flame?
The types of fuel gases used.
What determines the amount of gas that is being burned?
The size of the orifice in the tip, and thus the amount of heat that is being put into the work.
What is a carburizing flame?
a flame that has an excess of acetylene.
Why does a carburizing flame harden the surface of steel, and should therefore be avoided?
it adds carbon to the puddle so the weld is capable of being hardened more than the surrounding metal.
What is an AMS number?
SAE AMS Standard List: Coated Steels & Welding and Filler Materials. Abstract: A numeral index system is used to identify the compositions of the SAE steels, which makes it possible to use numerals that are partially descriptive of the composition of material covered by such numbers.
