High strength steels are steel which can be attained in various types, all which has a guaranteed value for yield strength as well as tensile strength.
Two of the main high strength steels available in South Africa are Domex and Supraform. Supraform is manufactured by Arcelor Mittal while the Domex range is manufactured by SSAB.
Both these high strength steels provide the end user, or the manufacturer of cold formed sections with steel that is weld able and improved toughness. Both these high strength steels are available from a 2mm minimum wall thickness. Supraform steel is available up to a 10mm while the Domex range is supplied up to 12mm wall thickness, depending on the strength of the material required.
The high strength steels are similar in comparison as is indicated in the table below:
|
SSAB |
Arcelor Mittal Range |
||
|
Product Name |
Yield Strength |
Product Name |
Yield Strength |
|
DOMEX 315 MC |
315 |
TM 340 |
340-420 |
|
DOMEX 420 MC |
420 |
TM 380 |
380-460 |
|
DOMEX 460 MC |
460 |
TM 420 |
420-500 |
|
DOMEX 500 MC |
500 |
TM 460 |
460-560 |
|
DOMEX 550 MC |
550 |
TM 600 |
600 |
|
DOMEX 600 MC |
600 |
|
|
|
DOMEX 650 MC |
650 |
|
|
|
DOMEX 700 MC |
700 |
|
|
One of the key factors for a steel tube or profile manufacturer when cold forming with high strength steel is to calculate the amount of spring-back that the material will have while being formed. As Domex and Supraform is a lot stronger than the normal steel in the market, such as S355 High Tensile, it has a wider spring-back range that should be accounted for. A potential way of countering the spring back when cold forming high strength steel as an open profile is to over form the material, then under form the material and in the last pass to re-form the material to the desired angle.
Tubecon have in the past cold formed open sections including lip channels and U-channels from Domex 700 as well as TM600 while rolling steel tubes and other welded sections from Domex 450.
