Stainless steel
Joining

A wide range of joining processes are available for stainless steels, though welding is by far the most common.

The ease of welding largely depends on the type of stainless steel used. Austenitic stainless steels are the easiest to weld by electric arc, with weld properties similar to those of the base metal (not cold-worked). Martensitic stainless steels can also be welded by electric-arc but, as the heat-affected zone (HAZ) and the fusion zone (FZ) form martensite upon cooling, precautions must be taken to avoid cracking of the weld. Improper welding practices can additionally cause sugaring (oxide scaling) and/or heat tint on the backside of the weld. This can be prevented with the use of back-purging gases, backing plates, and fluxes. Post-weld heat treatment is almost always required while preheating before welding is also necessary in some cases. Electric arc welding of type 430 ferritic stainless steel results in grain growth in the HAZ, which leads to brittleness. This has largely been overcome with stabilized ferritic grades, where niobium, titanium, and zirconium form precipitates that prevent grain growth. Duplex stainless steel welding by electric arc is a common practice but requires careful control of the process parameters. Otherwise, the precipitation of unwanted intermetallic phases occurs, which reduces the toughness of the welds.

Electric arc welding processes include:

MIG, MAG and TIG welding are the most common methods.

Other welding processes include:

Stainless steel may be bonded with adhesives such as silicone, silyl modified polymers, and epoxies. Acrylic and polyurethane adhesives are also used in some situations.
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