DUPLEX STAINLESS STEEL WIRE MATERIAL, STEEL WIRE, BOLT, AND METHOD FOR PRODUCTION OF THE BOLT

摘要

This austenite-ferrite duplex steel wire material for high strength highly corrosion resistant bolts, which has excellent cold forgeability and contains, in terms of mass %, C: 0.005 to 0.05%, Si: 0.1 to 1.0%, Mn: 0.1 to 10.0%: Ni: 1.0 to 6.0%, Cr: 19.0 to 30.0%, Cu: 0.05 to 3.0%, and N: 0.005 to 0.20%, with a remainder being iron and unavoidable impurities, wherein C+N is not more than 0.20%, an M value represented by formula (a) below is not more than 60, an F value represented by formula (b) below is from 45 to 85, and the tensile strength is within a range from 550 to 750 N/mm 2 . M = 551 - 462 �¢ C + N - 9.2 �¢ Si - 8.1 �¢ Mn - 29 �¢ Ni + Cu - 13.7 �¢ Cr - 18.5 �¢ Mo F = 5.6 �¢ Cr - 7.1 �¢ Ni + 2.4 �¢ Mo + 15 �¢ Si - 3.1 �¢ Mn - 300 �¢ C - 134 �¢ N - 26.6