High-strength steel processed products and a method of manufacturing excellent hardenability, as well as high strength and impact resistance and resistance to internal pressure fatigue fuel injection pipe for superior diesel engine on the characteristics and common rail manufacturing method of

摘要

PROBLEM TO BE SOLVED: To provide a worked article made of high strength steel which is excellent in a balance of strength-toughness and in hardenability and has high stability in retained austenite by the control of the additional amounts of components.;SOLUTION: The worked article has a composition comprising 0.1 to 0.7% C, ≤2.5% Si, 0.5 to 3% Mn, ≤1.5% Al, one or more kinds selected from among Nb, Ti and V in an amount of 0.01 to 0.3% in total, ≤2.0% Cr, ≤0.5% Mo, ≤2.0% Ni, two or more kinds selected from among Cr, Mo and Ni in an amount of 0.7 to 3.0% in total, carbon equivalent (Ceq) represented by expression; Ceq=C+Mn/6+Si/24+Ni/40+Cr/5+Mo/4+V/14 in an amount of 0.75 to 0.90, and the balance Fe with inevitable impurities, and has a structure containing ≥50% lath-like bainitic ferrite and small quantities of polygonal ferrite and granular bainitic ferrite, and has a second phase structure composed of retained austenite and martensite.;COPYRIGHT: (C)2010,JPO&INPIT