| 摘要 |
PROBLEM TO BE SOLVED: To provide a weld metal superior in tensile strength, toughness and low-temperature cracking resistance, even though a heat input and a temperature between paths are not strictly lowered. SOLUTION: The weld metal includes 0.03-0.12% C, (which means mass% and is hereafter the same concerning a component composition), 0.4-1.0% Si, 1.00-2.0% Mn and 0.010-0.10% Ti, also 0.2-2.5% Cu and/or 1.5-3.5% Ni, 1.0% or less Cr (excluding 0%) and/or 0.5-1.5% Mo, further one or more elements selected from the group consisting of 0.002% or less Mg (excluding 0%), 0.002% or less Ca (excluding 0%), 0.05% or less Al (excluding 0%) and 0.02-0.08% Zr, and the balance Fe with unavoidable impurities; has such a Z value expressed by the following expression (1) as to satisfy 2.00<Z<2.6: Z=1.75×[Mn]+[Ti]+2.5×[Mg]-10×[Ca]-12×[Al]+0.75×[Zr] (1), (wherein [ ] represents a content of each element (mass%)); and includes 3.0-10% retained austenite by a volume fraction. The retained austenite contains C in an amount of 0.9% or more. COPYRIGHT: (C)2011,JPO&INPIT |
