A roll cage is a specially engineered and constructed frame built in or around the passenger compartment of a vehicle to protect its occupants from being injured in an accident, particularly in the event of a roll-over.
There are many different roll cage designs depending on the application, hence different racing organisations have different specifications and regulations.
Another benefit of a roll cage is that it will also help to stiffen the chassis, which is desirable in racing applications.
There is often a comparison for “CDS” vs a high strength steel such as “T45” or “4130 Chromoly” for example. This is incorrect. CDS describes the manufacturing process of the steel as a Cold Drawn Seamless, of which many grades fall into this category, including T45 and 4130.
There are grades of CDS that do not meet the minimum strength figures (tensile & Yield) set out by the MSA and FIA and could make a roll cage ineligible for competition. It is important to specify a tube grade during manufacture, ROPT510 for example, and compare the grades properties to those set out by the governing body.
Materials such as BS4 T45, 4130, 25CRMO4 and 15CDV6 are all classed as high strength steels, and would often be found at the top end of Motorsport where weight saving is a priority over cost.