hello everyone welcome to Hua Guang's brazing demo video series in this video we are going to
show you how to braze copper and carbon steel with Hua Guang's 45% silver flux coated brazing rods
silver and copper are the two main elements of silver brazing alloys other elements such as
zinc tin manganese and nickel are added to form the silver-based alloy system
this 45% silver brazing rod is a kind of composite brazing product that has a layer of brazing flux
coated on its metal surface when used for flame brazing flux coated products enable us to add
brazing alloy and flux based on a fixed quantity ratio in this way gas release from the flux during
brazing can be significantly reduced we are able to improve production efficiency while maintaining
good brazing performance 45% silver flux coated brazing rods have a moderate brazing temperature
and their wetting properties and fluidity are excellent they also have features such
as high toughness electrical conductivity thermal conductivity and corrosion resistance which allow
them to form joints with strong vibration fatigue resistance and good overall mechanical properties
they are mainly used for the brazing of ferrous metals or non-ferrous metals with non-ferrous
metals 45% silver flux-coated brazing alloys are widely applied in the household appliance HVAC/R
and electric machinery industries the product used in this demo has a diameter of 1.6 millimeters and
the length of 457 millimeters the joints we use in this demo include t-joint and socket joint
and we will use flame brazing to braze copper and carbon steel to ensure quality and strength of the
braze joint we need to pay attention to gap width for each kind of joint gap width needs to be in
the 0.05 to 0.13 millimeter range blind holes are to be avoided in our socket joint designs
two steps of pre-braze preparations include cleaning of the base metals and assembly of the
brazing equipment the flame we choose is neutral flame and we use the outer flame to preheat and
heat the braze parts we point the brazing torch from side to side on the heating area
so as to avoid overheating a particular spot and to make sure temperature is uniform at each spot
socket joint is used for the brazing of tubes and pipes for this type of joints flame needs
to be kept level with the bell mouth for all other kinds of joints flame is to be kept at a
45 degree angle position relative to the length of the braze parts when base metal is turning light
red we feed the brazing rod on the side opposite to the flame something to be noted when we braze
tubings sometimes we need to switch the flame to the opposite side of its original position so as
to ensure filler metal can fill every spot of the gap flame is used to heat and melt flux coating
on the brazing rod facilitated by this molten flux brazing alloy melts and wets the base metals under
capillary action it fills the gap of the joint and it dissolves and diffuses with the base metals
after brazing let the brazed parts be air-cooled and solidify for a while and joining of the base
metals is now completed we put the brazed part into water bath then wipe away any slag and
residue on the surface using a towel after taking them out the brazed parts are dried with cool air
using an air blower which prevents corrosion we run relevant tests on the brazed parts to make
sure that they meet our specific application requirements common testing procedures include
appearance inspection and metallurgical observation for microstructure analysis
a high quality joint should not have defects such as slag blowhole crack and incomplete penetration
and metallurgical bonding with base metal should be optimal for socket joint we run penetration
inspection if necessary we will also test its tightness by air tightness test or kerosene
test to recap we used the popular 45% silver flux coated brazing alloy to flame braised copper and
carbon steel using t-joint and socket joint the most important takeaways are the brazing steps
first we clean the base metals then we assemble the equipment and fix them in place
thirdly we preheat and heat the braze parts brazing flux facilitates molten 45%
silver brazing alloy to wet the base metals and fill the gaps which then dissolves and diffuses
lastly we apply post-braze treatment and run the relevant tests thanks for watching you
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