Patent ID: 8794215

Claim:
A method of producing a common rail having a common rail body in which a rail hole and a branch hole which is formed in a cylindrical wall region enclosing the rail hole are formed, and a holder in which a communication hole communicating with the branch hole is formed, wherein the common rail body and the holder contain chemical components of 0.01-0.3 mass % of C, 0.01-0.5 mass % of Si, 0.01-3.0 mass % of Mn, 0.0003-0.01 mass % of B, 0.001-0.01 mass % of N, over 0.01-0.5 mass % of Al, 0.01-0.05 mass % of Ti, P limited to 0.03 mass % or less, S limited to 0.01 mass % or less, O limited to 0.01 mass % or less, a total content of As, Sn, Sb, Pb, and Zn limited to 0.015 mass % or less, and a balance including Fe and inevitable impurities, in which a TLB value represented by Formula (1): TLB=(B %)−[(N %)/1.3−{(Ti %)/3.4+(Al %)/4.1}×(Al %)×52] is 0.001% or more, the method comprising: inserting a Ni-based or Fe-based insert metal having 1 mass % or more of B, between the common rail body and the holder; performing liquid phase diffusion bonding so as to bond the common rail body, the insert metal, and the holder with a load of 1 MPa or more for 30 seconds or more at a bonding temperature of 1000-1300° C.; performing laser-peening by irradiating a pulsed laser beam with respect to a boundary peripheral region between an inside surface of the branch hole located near an opening peripheral zone of the branch hole, and an inside surface of the rail hole, the boundary peripheral region being provided with transparent liquid; and removing a surface layer of the opening peripheral zone, thereby increasing a fatigue strength of the opening peripheral zone.