Steel beams are used to create nearly all of the free-standing structures that humans depend on every day, from bridges to skyscrapers. These steel beams must themselves be fabricated using one of four methods.
Overview of Steel Fabrication
Steel beams can be separated into four classes based on the method of manufacture: rolled beams, extruded beams, welded beams and riveted beams.
Rolled and Extruded Beams
Rolled steel beams are made by forcing pliable metal through large rollers so as to flatten and mold it into the desired shape. Beams can be either hot-rolled or cold-rolled. Hot-rolled beams are made from metal that has been heated above the recrystallization point (over 1000 degrees, so the metal is very malleable) and then rolled. Cold-rolled beams are made from metal that has not been heated before rolling. Beams can also be fabricated by extrusion, in which the metal is forced through a die; this can also be done either hot or cold.
Welding or Riveting
Beams can also be fabricated by welding. In this process, sheets of metal are cut to the desired specifications and then welded together using industrial welding tools. The beams can be made by riveting as well. For riveting, sheets of metal are cut, holes are cut into the metal pieces and the pieces are held together by rivets to form beams.