Nippon Steel & Sumikin Stainless Steel Corporation

Nippon Steel Stainless Steel Corporation

Toyohiko Kakihara

Junichi Hamada

Ken Kimura

Akihiko Takahashi

Takashi Morohoshi

Yoshihito Yamada

Satoshi Hashimoto

Takuya Sakuraba

Yuji Kaga

A welded structure including a base material made of duplex stainless steel and a welded portion formed by welding the base materials to each other, wherein the base material has a predetermined chemical composition, a volume fraction of a ferrite phase in a metallographic structure of a weld metal of the welded portion is 45 to 75%, a ratio of a hardness of the weld metal to a hardness of the base material is 0.80 to 1.20, and an amount of precipitates formed in the ferrite phase of the weld metal is less than 10% in area fraction.

Welded structure and storage tank

The present invention provides a ferritic stainless steel casting and a sheet thereof excellent in deep drawability, punch stretchability and ridging resistance and a method for producing the casting and the sheet. In the present invention, a chemical composition is controlled so that the amounts of C, N, Si, Mn, P and Ti may be reduced to the utmost for securing high workability and, on the basis of the chemical composition, the roping and ridging of a steel sheet product is reduced by adding Mg, thus dispersing Mg containing oxides that accelerate the formation of nuclei for solidification and, resultantly, suppressing the development of coarse columnar crystals in a casting. The present invention is characterized in that the average composition of the Mg containing oxides dispersing in a casting satisfies the following expressions &#x3c;2&#x3e; and &#x3c;3&#x3e;,17.4(AlO)+3.9(MgO)+0.3(MgAlO)+18.7(CaO)&#x2266;500&#x2003;&#x2003;&#x3c;2&#x3e;,(AlO)+(MgO)+(MgAlO)+(CaO)&#x2267;95&#x2003;&#x2003;&#x3c;3&#x3e;.

Ferritic stainless steel casting and sheet and method for producing the same

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Tokyo, Japan

Toyohiko Kakihara