Spot welded joint
First Claim
1. A method of forming a spot welded joint, comprising:
- providing a plurality of overlapping steel sheets containing 0.001% to 0.05% of P; and
forming a nugget in an overlapped face of the plurality of the overlapping steel sheets, wherein the spot welded joint is formed by;
performing a main energizing process with a current value Iw (kA) for energizing time tw (msec) while applying a welding pressure,after performing the main energizing process, performing a solidification process by retaining an energizing with a current value Is (kA) satisfying an Expression (1) for an energizing time ts (msec) satisfying an Expression (2) while maintaining the welding pressure, andafter performing the solidification process, performing a post energizing process with a current value Ip (kA) satisfying an Expression (3) for an energizing time tp (msec) satisfying an Expression (4), the energizing time tp being 60 msec or longer, wherein the Expressions comprise;
0≤
Is≤
(½
)1/2×
Iw
(1),
α
2×
{2×
(Is2/Iw2)+1}×
h≤
ts≤
3×
α
2×
{2×
(Is2/Iw2)+1}×
h
(2),
Ip>
0.8×
Iw
(3), and
Ip2×
tp≤
Iw2×
tw
(4),where h is an average sheet thickness in terms of mm of the plurality of the overlapping steel sheets, and a is a nugget diameter (mm)/(h(mm))1/2.
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Accused Products
Abstract
In a spot welded joint according to an aspect of the present invention, with respect to a rectangular planar region of 100 μm×100 μm which is perpendicular to a sheet surface of the plurality of the steel sheets and which centers around an inner point spaced away by 100 μm in a direction parallel with the sheet surface from an edge of a nugget, in a case of measuring a P concentration at a pitch of 1 μm to obtain measured values of the P concentration at 100×100 of measurement points, and in a case of repetitively calculating an average value of the measured values of the P concentration at 20 of the measurement points which are adjacent to each other and which are arranged in a row in the direction parallel with the sheet surface among the 100×100 of the measurement points while shifting each one point to obtain 81×100 of the average values, the number of the average values which are more than two times an average P concentration is 0 to 100.
-
Citations
3 Claims
-
1. A method of forming a spot welded joint, comprising:
-
providing a plurality of overlapping steel sheets containing 0.001% to 0.05% of P; and forming a nugget in an overlapped face of the plurality of the overlapping steel sheets, wherein the spot welded joint is formed by; performing a main energizing process with a current value Iw (kA) for energizing time tw (msec) while applying a welding pressure, after performing the main energizing process, performing a solidification process by retaining an energizing with a current value Is (kA) satisfying an Expression (1) for an energizing time ts (msec) satisfying an Expression (2) while maintaining the welding pressure, and after performing the solidification process, performing a post energizing process with a current value Ip (kA) satisfying an Expression (3) for an energizing time tp (msec) satisfying an Expression (4), the energizing time tp being 60 msec or longer, wherein the Expressions comprise;
0≤
Is≤
(½
)1/2×
Iw
(1),
α
2×
{2×
(Is2/Iw2)+1}×
h≤
ts≤
3×
α
2×
{2×
(Is2/Iw2)+1}×
h
(2),
Ip>
0.8×
Iw
(3), and
Ip2×
tp≤
Iw2×
tw
(4),where h is an average sheet thickness in terms of mm of the plurality of the overlapping steel sheets, and a is a nugget diameter (mm)/(h(mm))1/2. - View Dependent Claims (2, 3)
-
Specification