January 25, 2008 -- ThyssenKrupp Steel and Japan's JFE Steel Corporation have developed a new ultra-strength steel in a bid to boost their positions in the automotive market.

The two steelmakers have patented TP-N 68/78, a new multiphase steel for automotive applications, available as hot-rolled coil and coated.

The steel, which has a minimum strength of 780 megapascals (MPa), has up to 40 percent higher elongation compared with conventional 780MPa high-strength steel and possesses significantly improved forming properties.

ThyssenKrupp expects high demand for this type of steel from the automotive industry, said a company spokesman. Carmakers' demand is driven by two needs; weight reduction to improve fuel efficiency, and high strength steel which also has good formability.

"The need for high strength and ductability is a contradiction in terms because what the carmakers are saying it that they want very strong steel which is also soft. The newly developed grade reconciles this contradiction. When delivered in its microstructure to the carmakers, the steel has both hard and soft properties, the soft of which become hard in the forming process," the spokesman said.

During the forming process the austenite content of the steel is transformed into hard martensite, which means that the steel only reaches its final strength during fabrication to the finished part. To achieve these properties, ThyssenKrupp Steel and JFE developed a new alloying concept and also employed new temperature-control methods during hot rolling and cooling.

Further joint developments for such high-strength steels will follow, said ThyssenKrupp in a statement.

Source: Metal Bulletin News Alert Service