US 2020/0056643 A1Published application

Welded member and method for manufacturing same

AssigneeNippon Steel Nisshin Co., Ltd.

InventorsKazuaki Hosomi, Tomokazu Nobutoki, Takefumi Nakako

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Abstract

A welded member includes a hot dip Zn-based alloy coated steel sheet as a base material and has excellent corrosion resistance and weld bead shear strength. In the welded member in which a lower sheet and an upper sheet, which are hot dip Zn-based alloy coated steel sheets, are stacked and arc-welded together, a weld bead is formed so that a cross-sectional width W satisfies the following formula 2T≤W≤6T, and a blowhole occupancy Br represented by the following formula (2) becomes not more than 50%: Br=(Σdi/L)×100, where T represents a thickness of the hot dip Zn-based alloy coated steel sheet, di represents a length of an i-th blowhole observed in X-ray radiography, and L represents a length of the weld bead.

Claims13

Dependent claims

A welded member comprising:

a first hot dip Zn-based alloy coated steel sheet;
a second hot dip Zn-based alloy coated steel sheet stacked on and arc-welded to a first sheet surface of the first hot dip Zn-based alloy coated steel sheet;
and
a weld bead that is provided on the first sheet surface such that the first hot dip Zn-based alloy coated steel sheet and the second hot dip Zn-based alloy coated steel sheet are welded together by the weld bead,
each of the first hot dip Zn-based alloy coated steel sheet and the second hot dip Zn-based alloy coated steel sheet having a coating weight of 15 g/m2 to 250 g/m2 per surface,
the weld bead being formed such that a cross-sectional width W satisfies a formula (1) below and a blowhole occupancy Br represented by a formula (2) below becomes not more than 50%, the cross-sectional width W being a width of a cross section from one boundary between a Zn-based coating layer and the weld bead to the other boundary between the Zn-based coating layer and the weld bead on the first sheet surface, and the cross section being obtained by cutting the weld bead by a plane orthogonal to a direction in which the weld bead extends,
the weld bead having at least two protrusion parts each of which protrudes into the first hot dip Zn-based alloy coated steel sheet in the cross section,
a protruding length of each of the at least two protrusion parts in the first hot dip Zn-based alloy coated steel sheet being not less than 0.2 mm, and the protruding length being not greater than a thickness of the first hot dip Zn-based alloy coated steel sheet,
2T≤W≤6T (1)
Br=(Σdi/L)×100 (2)
where:
T represents a thickness of any of the first hot dip Zn-based alloy coated steel sheet and the second hot dip Zn-based alloy coated steel sheet and, in a case where a thickness of the first hot dip Zn-based alloy coated steel sheet is different from a thickness of the second hot dip Zn-based alloy coated steel sheet, T represents a smaller one of the thickness of the first hot dip Zn-based alloy coated steel sheet and the thickness of the second hot dip Zn-based alloy coated steel sheet;
di represents a length of an i-th blowhole observed in X-ray radiography;
and
L represents a length of the weld bead.

12 more elements

A method for manufacturing a welded member by a pulsed arc welding process in which a second hot dip Zn-based alloy coated steel sheet that is stacked on a first sheet surface of a first hot dip Zn-based alloy coated steel sheet is arc-welded to the first hot dip Zn-based alloy coated steel sheet with an arc generated by alternately supplying a peak current and a base current, said method comprising:

a welding step of forming a weld bead on the first sheet surface such that the first hot dip Zn-based alloy coated steel sheet and the second hot dip Zn-based alloy coated steel sheet are welded together by the weld bead,
each of the first hot dip Zn-based alloy coated steel sheet and the second hot dip Zn-based alloy coated steel sheet having a coating weight of 15 g/m2 to 250 g/m2 per surface,
in the welding step, the pulsed arc welding process being carried out by using, as a shielding gas, an Ar—CO2 gas whose CO2 concentration is not less than 5% by volume and not more than 20% by volume,
in the welding step,
(i) the weld bead being formed such that a cross-sectional width W satisfies a formula (1) below and a blowhole occupancy Br represented by a formula (2) below becomes not more than 50%, the cross-sectional width W being a width of a cross section from one boundary between a Zn-based coating layer and the weld bead to the other boundary between the Zn-based coating layer and the weld bead on the first sheet surface, and the cross section being obtained by cutting the weld bead by a plane orthogonal to a direction in which the weld bead extends,
(ii) the arc welding being carried out such that a blowhole occupancy Br represented by a formula (2) below becomes not more than 50%, and
(iii) the weld bead being formed such that the weld bead has a protrusion part which protrudes into the first hot dip Zn-based alloy coated steel sheet in the cross section, a protruding length of the protrusion part in the first hot dip Zn-based alloy coated steel sheet being not less than 0.2 mm, and the protruding length being not greater than a thickness of the first hot dip Zn-based alloy coated steel sheet,
2T≤W≤6T (1)
Br=(Σdi/L)×100 (2)
where:
T represents a thickness of any of the first hot dip Zn-based alloy coated steel sheet and the second hot dip Zn-based alloy coated steel sheet and, in a case where a thickness of the first hot dip Zn-based alloy coated steel sheet is different from a thickness of the second hot dip Zn-based alloy coated steel sheet, T represents a smaller one of the thickness of the first hot dip Zn-based alloy coated steel sheet and the thickness of the second hot dip Zn-based alloy coated steel sheet;
di represents a length of an i-th blowhole observed in X-ray radiography;
and
L represents a length of the weld bead.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/344,435Filed 15 Sep 2017
Priority: JP 2016-21207428 Oct 2016
Published: 20 Feb 2020
Term ends: Not estimatedThe source records don’t support an estimate.

Classification34 codes

F16B 5/08
Joining sheets or plates , e.g. panels, to one another or to strips or bars parallel to them: by means of welds or the like
B23K 9/02
Arc welding or cutting: seam welding; Backing means; Inserts
B23K 9/0256
For rectilinear seams: for welding ribs on plates
B23K 9/09
Arc welding or cutting: arrangements or circuits for arc welding with pulsed current or voltage