US 2025/0144737 A1Published application

Method for manufacturing projection weld joint, projection weld joint, and vehicle component

AssigneesNippon Steel Corporation, Toyoda Iron Works Co., Ltd.

InventorsMasanori YASUYAMA, Masafumi AZUMA, Gen MURAYAMA, Takashi IMAMURA, Masatoshi TOKUNAGA, Koichi OI, Yoshinori OYAMA, Osamu KAWAGUCHI

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Abstract

A method for manufacturing a projection weld joint according to an aspect of the present invention includes: a first energizing step of energizing a steel sheet and a steel member so as to form a plurality of joint portions by projection welding a steel member to a first surface of a steel sheet that is a non-coated steel sheet or a zinc-type-coated steel sheet, in which the steel sheet has a tensile strength of 1.5 GPa or more, and the steel sheet has a Ceq of 0.30 mass % or more, and the manufacturing method further includes: a cooling step of quenching each of the plurality of joint portions; and a second energizing step of further energizing the steel sheet and the steel member so as to temper an end region in each of the plurality of joint portions.

Claims15

Dependent claims

A method for manufacturing a projection weld joint, the manufacturing method comprising a first energizing step of energizing a steel sheet and a steel member so as to form a plurality of joint portions by projection welding the steel member, which is a nut or a bolt having a plurality of projections, to a first surface of the steel sheet which is a non-coated steel sheet or a zinc-type-coated steel sheet,

wherein
the steel sheet has a tensile strength of 1.5 GPa or more, and
the steel sheet has a carbon equivalent Ceq calculated by following formula 1 of 0.30 mass % or more, and
when, in a cross section passing through the center of the steel member and the center of the joint portion and perpendicular to the first surface of the steel sheet, a position farthest from the center of the steel member in the joint portion is defined as an end portion of the joint portion, and a region from the end portion to a position 0.5 mm away from the end portion towards the center of the steel member along the first surface of the steel sheet in the joint portion is defined as an end region of the joint portion,
the manufacturing method further comprises:
a cooling step of quenching each of the plurality of joint portions;
and
a second energizing step of further energizing the steel sheet and the steel member so as to temper the end region in each of the plurality of joint portions,
Ceq
=
[
C
]
+
[
Si
]
/
30
+
[
Mn
]
/
20
+
2
×
[
P
]
+
4
×
[
S
]
:
formula
⁢
1
wherein the element symbol included in the formula 1 is a content of each element included in the steel sheet.

39 more elements

A projection weld joint comprising:

a steel sheet which is a non-coated steel sheet or a zinc-type-coated steel sheet;
a steel member which is a nut or a bolt;
and
a plurality of joint portions which join a first surface of the steel sheet and the steel member,
wherein
the steel sheet has a tensile strength of 1.5 GPa or more, and
the steel sheet has a carbon equivalent Ceq calculated by following formula 2 of 0.30 mass % or more, and
when, in a cross section passing through the center of the steel member and the center of the joint portion and perpendicular to the first surface of the steel sheet, a position farthest from the center of the steel member in the joint portion is defined as an end portion of the joint portion, and a region from the end portion to a position 0.5 mm away from the end portion towards the center of the steel member along the first surface of the steel sheet in the joint portion is defined as an end region of the joint portion,
a maximum hardness Hedge of the end region obtained by continuously measuring a Vickers hardness at a position 0.3 mm deep from the first surface in each of the plurality of joint portions satisfies a relationship of formula 3, and
a maximum hardness Hmax of the joint portions obtained by continuously measuring a Vickers hardness at a position 0.3 mm deep from the first surface in each of the plurality of joint portions satisfies a relationship of formula 4,
Ceq
=
[
C
]
+
[
Si
]
/
30
+
[
Mn
]
/
20
+
2
×
[
P
]
+
4
×
[
S
]
:
formula
⁢
2
Hedge
<
0.9
×
Hm
:
formula
⁢
3
H
⁢
max
>
0.9
×
Hm
:
formula
⁢
4
wherein the symbol Hm included in the formulas 3 and 4 is a value calculated by formula 5,
Hm
=
8
⁢
8
⁢
4
×
[
C
]
×
(
1
-
0.3
×
[
C
]
2
)
+
294
:
formula
⁢
5
wherein the element symbol included in the formula 2 and the formula 5 is a content of each element included in the steel sheet.

90 more elements

Dependencies are inferred from the claim text.

Facts

Application: 18/835,943Filed 23 Dec 2022
Priority: JP 2022-05032925 Mar 2022
Published: 8 May 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

B23K 11/14
Resistance welding; Severing by resistance heating: projection welding
B32B 15/013
All layers being exclusively metallic: one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or…
B23K 11/0053
The extremity of a small piece being welded to a base, e.g. cooling studs or fins to tubes or plates: stud welding, i.e. resistive
B23K 11/16
Resistance welding; Severing by resistance heating: taking account of the properties of the material to be welded

Family

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