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US-12617045-B2 - 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

US12617045B2US 12617045 B2US12617045 B2US 12617045B2US-12617045-B2

Abstract

An aspect of the present disclosure is to provide a gas shielded arc welding wire capable of imparting excellent fatigue resistance characteristics and resistance to deformation due to residual stress to a weld zone. Another aspect of the present disclosure is to provide a welding member having excellent fatigue resistance characteristics and resistance to deformation due to residual stress of a weld zone, and a method for manufacturing the same.

Inventors

  • Gyu-Yeol BAE

Assignees

  • POSCO CO., LTD

Dates

Publication Date
20260505
Application Date
20211220
Priority Date
20210916

Claims (14)

  1. 1 . A gas-shielded arc welding wire having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone, comprising, 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 in Equation 1 below is 300 to 500, 732−202×C+216×Si−85×Mn−37×Ni−47×Cr−39×Mo [Equation 1] where, a content of each element in [Equation 1] is in wt %.
  2. 2 . The gas-shielded arc welding wire having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 1 , wherein the wire further comprises at least one of 0.40% or less of Ni and 0.50% or less of Cu.
  3. 3 . The gas-shielded arc welding wire having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 1 , wherein the wire is one of a solid wire, a metal-cored wire and flux-cored wire.
  4. 4 . 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).
  5. 5 . The welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 4 , wherein the weld zone further comprises at least one of 0.40% or less of Ni and 0.50% or less of Cu.
  6. 6 . The welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 4 , wherein the weld zone has fatigue strength of 140 MPa or more.
  7. 7 . The welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 4 , wherein the weld zone has compressive residual stress of 90 MPa or more in a region within 5 mm from an end portion of a weld bead in a direction, perpendicular to a base material.
  8. 8 . The welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 4 , wherein the base material comprises, by weight %, 0.05 to 0.13% of C, 0.2 to 2.0% of Si, 1.3 to 3.0% of Mn, 0.01 to 2.0% of Cr, 0.01 to 2.0% of Mo, 0.01 to 0.1% of Al, 0.001 to 0.05% of P, 0.001 to 0.05% of S, and a remainder of Fe and other impurities.
  9. 9 . The welding member having excellent fatigue resistance characteristics and resistance to deformation due to residual stress of a weld zone of claim 8 , wherein the base material further comprises at least one of 0.01 to 0.2% of Ti and 0.01 to 0.1% of Nb.
  10. 10 . The welding member having fatigue resistance and resistance to deformation due to residual stress of a weld zone of claim 4 , wherein the base material has a thickness of 0.8 to 4.0 mm.
  11. 11 . 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.
  12. 12 . The method for manufacturing a welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 11 , wherein the base material comprises, by wt %, 0.05 to 0.13% of C, 0.2 to 2.0% of Si, 1.3 to 3.0% of Mn, 0.01 to 2.0% of Cr, 0.01 to 2.0% of Mo, 0.01 to 0.1% of Al, 0.001 to 0.05% of P, 0.001 to 0.05% of S, and a remainder of Fe and other impurities.
  13. 13 . The method for manufacturing a welding member having fatigue resistance characteristics and resistance to deformation due to residual stress of a weld zone of 12 , wherein the base material further comprises at least one of 0.01 to 0.2% of Ti and 0.01 to 0.1% of Nb.
  14. 14 . The method for manufacturing a welding member having fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone of claim 11 , wherein the base material has a thickness of 0.8 to 4.0 mm.

Description

CROSS-REFERENCE OF RELATED APPLICATIONS This application is the U.S. National Phase under 35 U.S.C. § 371 of International Patent Application No. PCT/KR2021/019365, filed on Dec. 20, 2021, which in turn claims the benefit of Korean Application No. 10-2020-0123734, filed on Sep. 16, 2021, the entire disclosures of which applications are incorporated by reference herein. TECHNICAL FIELD The present disclosure relates to a gas-shielded arc welding wire, a welding member having excellent fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone, and a method for manufacturing the same. BACKGROUND ART In the automotive field, research into light-weight technology for car bodies and parts is emerging as a major issue due to fuel economy regulation policies for environmental protection, such as to mitigate the effects of global warming. Chassis parts, which are important for vehicle driving performance, also require the application of high-strength steel for weight reduction in accordance with this principle. In order to achieve weight reduction of parts, it is essential to increase the strength of the material, and it is an important factor to guarantee durability of parts formed of high-strength steel in an environment in which repeated fatigue loads are applied. In the case of arc welding, which is mainly used to secure strength when assembling automobile chassis parts, since overlap joint welding is performed between parts by welding of a welding wire, it is unavoidable to provide a geometric shape of a joint portion. This acts as a repetitive fatigue stress concentration portion (notch effect) and becomes a fracture point, resulting in a decrease in the durability of the part, so that there is a limitation in which an advantage of applying high-strength steel is lost. It has been reported that, mainly reducing an angle (toe angle) of an end portion of a bead, which is a main stress concentration portion, is most important factor in the fatigue characteristics of the weld zone, and has no direct correlation with softening of a heat affected zone (HAZ) due to heat input from welding. According to Patent Document 1, in order to improve fatigue characteristics of an arc weld zone manufactured using a steel having a plate thickness of 5 mm or less and tensile strength of 780 MPa or more, a concept of material control for each position of a temperature section of a weld bead toe portion, that is, the heat affected zone (HAZ) (For example, the position of minimum hardness at a depth of 0.1 mm from a surface thereof must be at least 0.3 mm away from a melting line), was proposed, but there is a limitation that Patent Document 1 fails to disclose a technology to improve the strength of welding metal and control stress characteristics of the weld zone through the improvement of properties of a welding material. In Patent Document 2, it is suggested that the fatigue characteristics may be improved by applying a compressive stress by continuously hitting an end portion of a weld bead with a chipper (beating pin) to form a plastic deformation region. In Patent Document 3, in order to reduce a toe angle of arc weld bead between a sub-frame and a bracket, which are chassis parts for automobiles, a re-melting treatment method of the end portion of the weld bead through a plasma heat source after welding was proposed. However, the proposed methods have a problem in that a process cost increases when manufacturing parts because a post-welding process is added. Meanwhile, in general, in the case of a thin steel sheet having tensile strength of 950 MPa or more, deformation due to tensile residual stress occurs after arc welding for manufacturing chassis parts, which not only deteriorates assembly properties, but also reduces the fatigue characteristics of a weld zone due to the tensile residual stress of the weld zone. PRIOR ART DOCUMENT (Patent Document 1) Japanese Patent Laid-Open No. 2013-220431(Patent Document 2) Japanese Patent Laid-Open No. 2014-014831(Patent Document 3) Japanese Patent Laid-Open No. 2014-004609 SUMMARY OF INVENTION Technical Problem An aspect of the present disclosure is to provide a gas shielded arc welding wire capable of imparting excellent fatigue resistance characteristics and resistance to deformation due to residual stress to a weld zone. Another aspect of the present disclosure is to provide a welding member having excellent fatigue resistance characteristics and resistance to deformation due to residual stress of a weld zone, and a method for manufacturing the same. Solution to Problem According to an aspect of the present disclosure, a gas-shielded arc welding wire having excellent fatigue resistance characteristics and resistance to deformation due to residual stress in a weld zone is provided, the gas-shielded arc welding wire including, 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