- Adhesive (glue)
- Cohesive (sharing electrons)
- Mechanical (nail, screw, tape)
Higher energy density of welding will produce a join with fewer structural problems.
Flame, arc, plasma, laser, and electron beam are types of welding processes that increase in energy densities.
The heat affected zone is the area on either side of the weld. This area will have large grain structure which will have a lower strength than the weld metal and the metal elsewhere.
Defects in welding:
- weld spatter
- too much heat causing undercutting
- incomplete weld
- gas porosity in weld
- moisture in the weld or on the surface of the steel
Arc welding: uses high current and low voltage. Liquid metal from the welding rod fills the gap, this welding rod is covered in whats called flux. This flux serves an important purpose, it keep impurities out of the weld. It keep air away and dissolves metal oxides.
Plasma Arc: uses temperatures up to 60,000 degrees F. Used on thick sections. High productivity.
Electron Beam: high quality weld, requires x-ray shielding.
Oxyfuel gas welding: low energy density, most common gas acetylene and oxygen.
Resistance welding: used in auto body manufacturing with about 10,000 welds. This is a common weld because it's fast and cost efficient.
