Roll cage tubing (2) – debunking the myths.
As major roll cage manufacturers in the UK, we carry and use (and supply) a variety of steel tube specifications. The highest spec tube is called 15CDV6, but we also use and supply 25CrMo4, 4130, T45 (BS 4T45) as well as CDS (Cold Drawn Seamless).
By far and away our biggest selling tube is T45. This is a High Tensile Carbon-Manganese cold drawn seamless tube with excellent properties for bending and welding (i.e. – ideal for roll cages). Originally developed during the First World War as axle tubing for planes as it was high strength, ductile, and weld-able without pre or post-heat-treatment.
- Yield strength – min. 620 MPa. (N/mm2)
- Tensile strength – min. 700 MPa.
- Elongation – normally around 15%, although this will depend
slightly on the final heat treat temperature.
- Uses: Roll cages, suspension components, anti-roll bars.
A Continental/European spec tube, very similar in terms of properties to T45.
- Much lower quantities of Manganese, but higher Chrome
- Almost identical in terms of composition and properties to 4130
- Readily weld-able with the correct procedures.
- Generally slightly stronger in tensile than T45, but
elongation is slightly lower. More susceptible to cracking under bending and
- Yield strength – min. 600 MPa.
- Tensile – 700 – 900 MPa.
- Elongation – normally around 10% to 12%.
A micro-structured alloy steel with very high strength and excellent weld-ability.
- Due to it’s refined structure it is highly expensive to produce but is approximately 40% stronger than most other tubes.
- Ideal for use in suspension components and wishbones. Use in
roll cages negated a little nowadays with the FIA insistence of tubes being a
minimum of 1.5 mm wall.
- Yield strength – 900 MPa
- Tensile strength – 1100 MPa
- Elongation – min. 15%.
CDS (Cold Drawn Seamless).
The term CDS covers all of the above tubes because they are all produced via a cold drawing process and are all seamless. However, they are all differentiated by their chemical composition and the heat treatment processes by which they are finished. Even the material most often referred to as CDS has multiple variations, both of chemical composition and physical properties. What was always called CDS2 (then CFS3 and latterly known as E235) has a tensile strength of approximately 350 MPa. However, Custom Cages uses a CDS of a much higher specification. Originally designated CFS5, but nowadays called E355. When produced with the required heat-treatment this has excellent properties for basic roll cages.
- Tensile strength – minimum 510 MPa.
- Yield strength – minimum 370 MPa.
- Elongation – minimum 25%.