The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 28, 1989
Filed:
Dec. 09, 1988
Masanori Ueda, Kitakyushu, JP;
Masayuki Abe, Kitakyushu, JP;
Kensai Shitani, Hikari, JP;
Tetsuo Yoshimoto, Kitakyushu, JP;
Hiroki Yamamoto, Kitakyushu, JP;
Fumio Kurosawa, Kawasaki, JP;
Nippon Steel Corporation, Tokyo, JP;
Abstract
In a continuously cast piece of austenitic stainless steel having a large amount of Mo, segregation of alloy elements such as Mo and Cr is caused at the center part in the thickness direction of the slab, and the .sigma.-phase is precipitated during the step of cooling the cast piece. When a heavy plate or hot coil is prepared from this cast piece as the starting material, cracking occurs in the hot-working step and the corrosion resistance of the final product is degraded. According to the present invention, at the cast piece-forming step, the super-heating degree of the molten steel is controlled to at least 25.degree. C., whereby the equiaxed zone ratio is controlled to below 25%. When the heating times at the soaking and hot rolling treatments and the conditions for annealing the obtained steel sheet are controlled, the pitting resistance of the steel plate is greatly improved and cracking is prevented at the hot-working step.