Abstract: Disclosed is a high hardness stainless steel suitable as the material for screws used in fastening parts of magnetic memory devices such as hard disk drives. The stainless steel consists essentially of, by weight %, C: 0.03-0.15%, Si: 0.1-1.2%, Mn: 11.0-19.0%, P: up to 0.06%, S: up to 0.03%, Ni: 2.0-7.0%, Cr: 16.5-19.0%, N: 0.20-0.45% and the balance of Fe and inevitable impurities. This stainless steel exhibits improved hardness and anti-seizure property better than those of conventionally used SUS XM7. The steel may further contain at least one member of Al: up to 0.05%, Mg: 0.001-0.05%, Ca: 0.001-0.05%, V: 0.03-0.30% and Nb: 0.03-0.30%; and one or both of Cu: 1.0-4.0% and Mo: 0.5-5.0%.

Abstract: Disclosed is a high hardness stainless steel suitable as the material for screws used in fastening parts of magnetic memory devices such as hard disk drives. The stainless steel consists essentially of, by weight %, C: 0.03-0.15%, Si: 0.1-1.2%, Mn: 11.0-19.0%, P: up to 0.06%, S: up to 0.03%, Ni: 2.0-7.0%, Cr: 16.5-19.0%, N: 0.20-0.45% and the balance of Fe and inevitable impurities. This stainless steel exhibits improved hardness and anti-seizure property better than those of conventionally used SUS XM7. The steel may further contain at least one member of Al: up to 0.05%, Mg: 0.001-0.05%, Ca: 0.001-0.05%, V: 0.03-0.30% and Nb: 0.03-0.30%; and one or both of Cu: 1.0-4.0% and Mo: 0.5-5.0%.

Abstract: A high toughness ferritic stainless steel having the excellent cold workability and the excellent heading workability suitable for the plastic working of screws, which consists essentially of, by weight percentage, C.ltoreq.0.03%, P.ltoreq.0.040%, S.ltoreq.0.010%, Si.ltoreq.1.0%, Mn.ltoreq.1.0%, 11.5%.ltoreq.Cr.ltoreq.22.0%, 0.05%.ltoreq.Nb.ltoreq.0.80%, N.ltoreq.0.025%, if necessary at least one selected from 0.2%.ltoreq.Cu.ltoreq.1.0%, 0.01.ltoreq.Mo.ltoreq.2.00%, 0.020%.ltoreq.Ni.ltoreq.1.50% and the balance being Fe and inevitable impurities, and the number of inclusions larger than 20 .mu.m amoung inclusions composed of carbo-nitrides of Nb, Ti and/or Zr in the steel is not more than 20. In the production of the high toughness ferritic stainless steel, the rolling material having the above-mentioned chemical compositions is heated to 1200.degree. C. or above at the rod rolling.