Granted Patent B2

US 12,459,049 · App. 17/289,537 · Granted Nov 4, 2025

Inventors: Gyu-Yeol Bae (Incheon, KR); Ho-Soo Kim (Incheon, KR)

Assignee: POSCO CO., LTD

B23K9/23B23K9/092B23K9/095B23K9/1006B23K9/16B23K2101/34B23K2103/04

Abstract

Claims (9)

1 . A lap-joint welding method of welding a first zinc coated steel sheet and a second zinc coated steel sheet stacked to partially overlap the first zinc coated steel sheet using a welding wire, to reduce a porosity defect of welded metal, comprising:

welding, wherein the welded metal has a pore area ratio of 0.97% or less and have a tensile strength of 700 MPa or more,

wherein a gap of a welded joint formed by the method is 0 mm,

wherein the welding current is supplied as a bidirectional pulse current in which positive direct current and negative direct current are of equal and constant absolute value in a range from 200 A to 270 A, and

wherein a welding polarity is alternately altered to satisfy a welding polarity fraction, in a range of 0.25 to 0.35, the welding polarity being defined by

EN R,% /(EP R,% +EN R,% )

where, EN R, % is a fraction of time for which current through the welding wire is negative direct current, and EP R, % is a fraction of time for which current through the welding wire is positive direct current.

2 . The method of claim 1 , wherein the welding wire is an E70C-GS Φ1.0 metal cored wire.

3 . The method of claim 1 , wherein the zinc coated steel sheet is HGI 780HB steel.

Assignments (3)

Priority Claims (1)

Continuity (1)

References Cited (43)