Research Institute of Industrial Science & Technology

Pohang Iron & Steel Co. Ltd.

Yong Heon Lee

Jae Sin Park

Do Y Ryoo

Eung J Kim

Bong Un Kim

Kwang Tae Kim

Hyun C Kim

Yong Deuk Lee

Duplex stainless steel, and its manufacturing method

An austenitic stainless steel and a manufacturing process therefor are disclosed, in which, instead of the expensive Ni, there are added Cu as an austenite (.tau.) stabilizing element, and tiny amounts of Ti as a ferrite forming element and B for improvement of high temperature hot workability, so that the optimum Md.sub.30 temperature and the optimum delta-ferrite content can be controlled, thereby improving the formability, the season cracking resistance, the hot workability and the high temperature oxidation resistance, and reducing the surface defects during the hot rolling and saving the manufacturing cost by reducing the content of Ni. The austenitic stainless steel according to the present invention includes in weight %: less than 0.07% of C, less than 1.0% of Si, less than 2.0% of Mn, 16-18% of Cr, 6.0-8.0% of Ni, less than 0.005% of Al, less than 0.05% of P, less than 0.005% of S, less than 0.03% of Ti, less than 0.003% of B, less than 3.0% of Cu, less than 0.3% of Mo, less than 0.1% of Nb, less than 0.045% of N, the balance of Fe, and other indispensable impurities. Thus the present invention improves the press formability, the season cracking resistance, the hot workability, and the high temperature oxidation resistance.

Austenitic stainless steel having superior press-formability, hot

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Pohang, South Korea

Yong Heon Lee