The steel for volt/bolt and the production manner null of volt/bolt which form from the bonde membrane attaching wire rod which is superior in resistance retarded breaking Characteristic

摘要

PROBLEM TO BE SOLVED: To provide a steel for a bolt low in cost and capable of obtaining the bolt excellent in delayed fracture resistance even in the case that a bonderized coating film is applied, thereafter a wire drawing and a bolt forming are performed.;SOLUTION: The steel for a bolt has a chemical composition containing, by weight, 0.22 to 0.32% C, ≤0.20% Si, 0.60 to 1.20% Mn, ≤0.015% P, ≤0.005% S, 0.07 to 0.25% Cu, 0.03 to 0.20% Ni, 0.10 to 0.40% Cu+Ni, 0.05 to 0.45% Cr, 0.01 to 0.10% Ti, 0.01 to 0.06% Nb, 0.002 to 0.010% N and 0.0005 to 0.0030% B, and the balance Fe with inevitable impurities.;COPYRIGHT: (C)2005,JPO&NCIPI