Production Methods of Stainless Steel Beams
Hot Rolling of Stainless Steel Beams
As for all structural steel shapes, the most cost efficient production technology for stainless steel beams is hot rolling as well. Unfortunately, there is a technical limitation: hot rolling requires sufficient volumes to justify a rolling campaign. However, today the worldwide annual consumption does not reach the minimum quantity for all beam types and sizes.Hence, there are only few sizes of stainless steel beams that rolling mills do hot roll. The standard of the bars’ length for stainless steel section is six meters (20 feet) and customized lengths cannot be considered at all.
Hot Extruding of Stainless Steel Beams
Another production technology for stainless steel beams is hot steel extrusion. Hot extrusion of stainless steel beams does not demand for minimum quantities, also small batches of only a few bars are possible. Beams with conical flanges can be hot extruded easily. The downside of hot extrusion is the limited size range, which encompasses beams up to 150 millimeters and less accurate dimensional tolerances. In the smaller size range, the standards define material thicknesses of four to six millimeters. The extruded stainless steel beams require a bigger thickness there, increasing overall weight and loosing compliance to the standards.
Bolting of Stainless Steel Beams
Another way to realize stainless steel beams was bolting together two stainless steel channels, either hot rolled or by press brake. This was common practice in the past, but lost importance due to global availability of stainless steel beams. Nowadays, this solution is rarely used and not allowed for many applications.
A much more common production method, probably the most popular, is welding. There are different types of welding that give different results.
MAG Welding of Stainless Steel Beams
Welding is a production method that brings an important amount of heat into the material. Unlike carbon steel, stainless steel is much more prone to distortion and deformation when heated up during the welding process.
As a result, small size stainless steel beams cannot be properly welded by using conventional welding methods like TIG/MAG or plasma welding. The heat input deforms the built up beams so much, that straightening becomes impossible.
Larger stainless steel beams are normally MAG fillet welded. In order to compensate distortion of the flanges, generally they are pre-bend to the opposite direction, so that the weld heat “pulls” them into a flush position.
Laser Welding of Stainless Steel Beams
Another welding method, that does not bring up these big issues with straightening due to heat input, is laser welding.
Laser welding technology allows non-restrictive production of stainless steel beams from small to medium and large size beams. Likewise, for conventional welding and hot extrusion, there are no minimum runs; one single bar is feasible. Laser welding melts web and flanges together without additional filler metal. The distortion is strongly reduced, as the heat is limited to a little area called “plasma pool”. As stainless steel sheets are the raw material base for built-up beams, there is a great flexibility as far as special length is concerned.