Importance

Loading Importance Indicators...

Abstract

To provide a wire rod for bolts that has excellent acid pickling properties and the resistance to delayed fracture after quenching and tempering, and a bolt using the same. Disclosed is a wire rod for bolts that has excellent acid pickling properties and resistance to delayed fracture, including, in percent by mass: C: 0.3 to 0.6%; Si: 1.0 to 3.0%; Mn: 0.1 to 1.5%; P: more than 0% and 0.020% or less; S: more than 0% and 0.020% or less; Cr: 0.3 to 1.5%; Al: 0.02 to 0.10%; and N: 0.001 to 0.020%, with the balance being iron and inevitable impurities, wherein in a d× 1/4 position of the wire rod, where d is a diameter of the wire rod, a ferrite area ratio is in a range of 10 to 40%, with the remaining microstructure being bainite, pearlite and an inevitably formed microstructure, and a C content in a position at a depth of 0.1 mm from a surface layer of the wire rod is in a range of 50 to 100% of a C content in a base material.

Loading the Abstract Image...

First Claim