100c User Manual
50
ch.7
High Carbon Steels (Spring Steel / Tool Steel)
High carbon steel welds easily but may become brittle after the welding process. To avoid weld
failure the part must be heat treated after the welding process.
Cobalt Chrome Alloys
Cobalt Chrome is very sensitive to oxygen contamination. If there is insufficient argon coverage or
oxygen present in the argon gas this alloy will crack. Once oxygen embrittlement has occurred the
weld area must be removed (via grinding etc) to prevent future cracking over the same area.
Copper
Copper is one of the more difficult alloys to weld because of its high heat capacity and high
thermal conductivity. ese factors make it even more difficult to weld than silver. Copper also
requires more energy than silver for the weld to take place (about 30% more). in copper,
however, welds very easily and lower energy is typically sufficient to produce very strong welds.
For thicker copper similar techniques as those employed to weld silver must be used.
Brass
Brass is a material that contains a large amount of zinc - 30 -37% zinc by composition. e
remaining material is copper.
As discussed previously, zinc is a hard metal to pulse arc weld or resistance weld because of its
low melting and boiling temperature (420 deg C, 907 deg C).
During the melting process the low temperature zinc evaporates/boils out of the brass alloy.
For low energies this simply coats the surrounding material in a black zinc film that can easily be
removed with a glass brush.
For larger pulse arc weld energies the black coat can cover larger areas and porosity can develop
at the weld location as zinc boils from the weld.
Joining Different Metals
Welding different metals together will produce a new alloy at the weld location. e new alloy will
have different properties (although in many cases similar properties) to the base metals. Some
metals combine well, forming a strong and useful new alloy. Other metal combinations are weak
and brittle.
Helpful Hints for Combining Different Metals
1. Check the new alloy strength with scrap material to ensure the joint will turn out as expected.
2. You may need to weld over the joint location several times to get complete mixing of the
weld pool and a uniform new alloy. In most cases this is not necessary for a strong joint and
the first weld will be sufficient.
3. Some material combinations may benefit from a third metal at the joint which forms a
better/stronger alloy with the two primary metals.
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