Flashcards in Brazing Deck (11):
How is brazing better than welding?
They require lower temperatures than fusion welding.
What occurs during the filler process?
A filler metal is placed between the faying surfaces to be joined.
Filler metals are melted by an external source of heat
What are the selection criteria for what type of filler is used?
Grain boundary penetration of liquid metal
formation of brittle intermetallic compounds at the joint
galvanic corrosion in the joint
Why are fluxes used?
prevent oxidation and removes oxide films
wetting agents is added to improve the wetting characteristics of the molten filler metal and the capillary action
Why are surfaces brazed
for proper wetting and spreading of the molten filler in the joint
to develop maximum bond strength
what does the brazed joint strength depend on?
nature of the bond at the interface between the components and the filler metal
surfaces to be brazed must be cleaned chemically or mechanically
How is torch brazing done?
the source is heated with oxyfuel gas
difficult to control and requires skilled labour
can be automated
can be used for repair work
What are brazing and soldering used for?
They are an adhesive bonding since the low melt point of alloys flows into the gap between parent plates
How is brazing carried out?
At low temperatures so the base melt does not melt and fusion does not occur
What does the strength of a brazed joint depend on?
nature of the chemical bond at the interface