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silver parts may require a weld projection or “bump” to focus the weld current . This welding
strategy is discussed in detail in Chapter 4 - Tack Welding .
Aluminum (Al)
Aluminum behaves very much like silver during the pulse arc welding process . Aluminum has a
very low melting temperature (660 deg C) and is very mobile when in a liquid phase . This means
that the same principles that apply to welding silver also apply to Aluminum . Aluminum also
has one additional complication that may make it difficult to work with in some situations . This
metal is very susceptible to hot cracking . On occasion the weld parameters or geometry may be
such that a crack may appear in the weld . Always perform test welds for strength verification . In
general, pulse arc welding in aluminum will produce a weaker weld than with other metals .
Stainless Steel
Stainless steels are relatively simple to weld . The weld puddle looks smooth and joins easily and
the resulting weld joint is strong . Because of the low thermal conductivity of stainless steel, it is
easy to hold the work piece in hand while welding without weld heat immediately making the work
piece too hot to hold . Use only stainless steel fill wire when welding . If regular low carbon steel is
used, the weld joint will eventually rust over time .
Austenitic stainless steels, (304 for example) weld easily . However, hot cracking is a possibility
with this material . To help avoid any cracking it is helpful to weld using an alloy that will produce
a small amount of ferritic crystal structure in the weld joint . The addition of the ferritic crystal
structure will help suppress cracking . For example, when welding 304 stainless, a 308 stainless fill
wire can be used . Not all situations will require crack suppression techniques . Smaller parts, like
those typically welded using the Orion, do not require these procedures . (201, 202, 205, 216, 301,
302, 303, 304, 305, 308, 309, 310, 312, 314, 316, 317, 321, 329, 330, 332, 347, 348, 384, 385 stainless
steels) .
Martensitic stainless steels (410 for example) have a high carbon content . This high carbon
content increases the risk of cracking . To decrease the risk of cracking it may be helpful to
increase the work piece temperature to between 200 – 300 deg C . Often material thinner than
3mm can be welded successfully without heat treatment provided that pure argon is used during
the welding process . (403, 410, 414, 416, 418, 420, 422, 431, 440, 501, 502, 503, 504 stainless
steels) .
Low Carbon Steels (Mild Steel)
Low carbon steels typically weld easily with no major cautions . Please be advised that low carbon
steel will rust and will often come with a coating of zinc . The zinc coating will cause the metal to
appear more white or lustrous than typical steel . As discussed above, welding on zinc will cause
many issues to consider . The zinc will evaporate quickly from the weld area causing a black coat
to spread to the surrounding metal (including the welding stylus) . The zinc evaporation may also
cause strange weld behavior, etc .
For best results select a low carbon steel without a zinc coating . Make sure the steel is free from
other contaminates such as rust or oil . Remember that if using the Orion to produce welds in very
thick pieces the weld joint may need to be prepared as discussed previously .