Gas-shielded arc welding wire and welding member having excellent fatigue resistance characteristics and resistance to deformation due to residual stress in weld zone, and method for manufacturing same

A welding member including a base material and a weld zone, the welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone,

• wherein the weld zone comprises, by weight %, 0.05 to 0.16% of C, 0.001 to 1.0% of Si, 1.4 to 2.5% of Mn, 0.4 to 5.0% of Cr, 0.1 to 1.5% of Mo, 0.015% or less (excluding 0%) of P, 0.01% or less (excluding 0%) of S, 0.20% or less (excluding 0%) of Al, and a remainder of Fe and other impurities,
• wherein the weld zone has a microstructure including bainite;
• acicular ferrite;
• and at least one of granular ferrite, martensite and retained austenite;
• wherein the microstructure has an average effective grain size of 10 μm or less, and a ratio of high angle grain boundaries with a misorientation angle between grain boundaries of 55° or more respective to the total grain boundaries is 40% or more, and
• a value of R expressed by the following Equation 2 is 10.5 to 18.5,
• R=(K/G)×(Q/T) where, in [Equation 2], [Equation 2]
• K is a ratio of grain boundaries with a misorientation angle of 55° or more relative to total grain boundaries in a weld zone (%), G is an average effective grain size of the weld zone (m), T is a thickness of a base material (mm), and Q is a welding heat input (kJ/cm), where Q is defined by the following [Equation 3]
• Q=(I×E)×0.048/v [Equation 3]
• where, in [Equation 3], I is a welding current (A), E is a welding voltage (V), and v is a welding speed (cm/min).

A method for manufacturing a welding member obtained by preparing two or more base materials, and then gas-shielded arc welding using a welding wire, the method for manufacturing a welding member having fatigue resistance characteristics and resistance to deformation due to residual stress of a weld zone,

• wherein the welding wire comprises, by weight %, 0.06 to 0.16% of C, 0.001 to 0.2% of Si, 1.6 to 1.9% of Mn, 1.2 to 6.0% of Cr, 0.4 to 0.65% of Mo, 0.015% or less (excluding 0%) of P, 0.01% or less (excluding 0%) of S, 0.20% or less (excluding 0%) of Al, and a remainder of Fe and other impurities, wherein a value of Equation 1 below is 300 to 500,
• wherein, during the gas-shielded arc welding, a value of Equation 4 below is 1.2 to 1.6,
• 732−202×C+216×Si−85×Mn−37×Ni−47×Cr−39×Mo [Equation 1]
• where, in [Equation 1], a content of each element is in wt %
• Q/T [Equation 4]
• where, in [Equation 4], T is a thickness of a base material (mm) and Q is a welding heat input (kJ/cm), where Q is defined by the following [Equation 3] [Equation 3] Q=(I×E)×0.048/o where, in [Equation 3], I is a welding current (A), E is a welding voltage (V), and v is a welding speed (cm/min),
• wherein the weld zone has a microstructure including bainite;
• acicular ferrite;
• and at least one of granular ferrite, martensite and retained austenite.