Sandvik Intellectual Property Ab

Sandvik Ab

Johan Frodigh

Pasi Kangas

Ulf Kivisäkk

Babak Bahar

A super-austenitic stainless steel alloy with a composition, balanced in such a way that products made from the alloy fulfill high requirements on a combination of high corrosion resistance, especially in inorganic and organic acids and mixtures thereof, good general corrosion resistance, good structure stability as well as improved mechanical properties in combination with good workability, in particular in tubes, especially seamless tubes and seam welded tubes for application in these environments and with following composition, in weight-percent: up to 2.0 of one or more element of the group Mg, Ce, Ca, B, La, Pr, Zr, Ti, Nd, and the balance being Fe and normally occurring impurities and steel making additions.

Super-austenitic stainless steel

A duplex ferritic-austenitic stainless steel alloy provided for seawater applications includes, in weight %: C maximum 0.05; Si maximum 0.8; Mn 0.03-4; Cr 28-35; Ni 3-10%, Mo 1.0-4.0; N 0.2-0.6; Cu maximum 1.0; W maximum 2.0; S maximum 0.010; Ce maximum 0.2; and the balance Fe together with normally occurring impurities and additives, wherein the ferritic content is 30-70 volume %, the alloy composition has a PRE-value higher than 42, and the PRE-value is at least 40 in both the ferritic and austenitic phases. A method is also provided which includes: providing a duplex ferritic-austenitic stainless steel alloy with the above-noted composition, forming a component with the alloy, and contacting the component with seawater. In preferred embodiments, the component comprises at least one of tubes, bars, heavy castings, forging, plates, wire or strip.

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Sandviken, Sweden

Johan Frodigh