Ferrite steel which excels in high-temperature strength and toughness

Abstract

A ferrite steel suitable for use as the material of a part which is used at high and which is required to have high toughness at weld heat affected zones. The ferrite steel has a composition which contains C: not more than 0.02 wt %, Si: not more than 2.0 wt %, Mn: not more than 1.0 wt %, Cr: not less than 6.0 wt % but not more than 23.0 wt %, Ni: not more than 1.0 wt %, Nb: not less than 0.4 wt % but not more than 0.65 wt %, Co: not less than 0.01 wt % but not more than 2.0 wt %, Al: not more than 0.5 wt %, N: not more than 0.03 wt % and the balance substantially Fe and incidental inclusions.

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