YS300 history

YS300 was the first structural tube steel grade to be developed in South Africa and was introduced to the market in 1997. This development started with the 300WA analysis as a base. Due to welding problems, it had to be re-designed to a leaner analysis. From a low base, the demand for this product grew to approximately 75 000 ton in 2008.

Why change?

The focus in the entire steel industry became “Stronger & Lighter”. During the same period, the Truck & Trailer industry managed to reduce the mass of trailers by almost 50% by moving to high strength steels. The next to follow was structural steels to move from 300MPa to 350MPa. In 2008 the “Red Book” was changed to specify S355 as the base design grade. In 2009, SANS also “adopted” the Euro Norm structural specifications. (EN 10025) Thus only the tube steel grade remained on 300MPa.

The development process

The first trial coils were based on the S355 structural analysis (Tensile 470MPa min). During the tube making trials, it was found that the product had good welding and forming properties, but that the strength was too high. The product was therefore re-designed based on the EN 10219 specification (Tensile 450MPa min). On completion of the second trials, the entire industry was convinced that this product is a huge success.

Properties

YS300

S355 Tube

Min Yield strength

300MPa

355MPa

Chemistry

Carbon-Manganese

Micro alloyed

Hot Dip Galvanizing

Low Si; 0,03%

Si = 0,15 – 0,25%

?

Although P is specified as 0,035% max but in most incidences will be a max of 0,012%.

Carbon equivalent

±0,34

±0,20

Weldability

Acceptable

Good

Formability

Acceptable

Good

Toughness

Good

Excellent

Conclusion

ArcelorMittal is proud to be part of the development of this steel for the tube industry. The S355 tube specification is definitely an improvement on the YS300 product in many ways. This product is now not only aligned with the rest of the structural- and plate steel grades, but also conforms to international standards. YS300 tube was phased out the end of February 2010. As from March 2010, only S355 tube will be available.

Jan Kotzé