| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a high strength bolt having 1,200 MPa or higher of tensile strength and excellent in lagging destruction resistance, which is non-refining bolt saving a quenching and tempering processes after molding the bolt; and to provide a steel wire for high strength bolt excellent in a cold forgeability for using the bolt, and a manufacturing method therefor. <P>SOLUTION: The steel wire for bolt, contains C, Si, Mn, P, S, Cr, Al, N, B and at least one kind selected from the group composed of Ti, V and Nb and as the balance, Fe with inevitable impurities. Further, a microstrucure in the steel wire is the two-phase structure of ferrite and pearlite, and the lamellar spacing of the pearlite is 250 nm or lower and the area ratio of the pearlite is >40% to 80% and also, the tensile strength is 1,300 MPa or lower. <P>COPYRIGHT: (C)2013,JPO&INPIT |
