Tailor welded blank, and tailor welded blank production method and tailor welded blank production apparatus
AssigneeJfe Steel Corporation
InventorMuneo MATSUSHITA
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Abstract
Provided is a tailor welded blank that can be produced at low cost with high productivity and that has excellent press workability, even when thin steel sheets are used as materials. A butt joint includes a stir zone and thermo-mechanically affected zones adjacent to the stir zone, and the stir zone has an upper stir zone and a lower stir zone adjacent to each other in a thickness direction, and the tailor welded blank satisfies the relationships according to the following formulas (1) to (3): Pj≥0.9×PbmL . . . (1); TszL≥0.9×TbmL . . . (2); and TszH≤1.1×TbmH . . . (3).
Claims20
A tailor welded blank comprising a first steel sheet, a second steel sheet, and a butt joint joining the first steel sheet and the second steel sheet, wherein
- the butt joint includes a stir zone and thermo-mechanically affected zones adjacent to the stir zone,
- the stir zone has an upper stir zone and a lower stir zone adjacent to each other in a thickness direction of the tailor welded blank, and
- the relationships according to the following formulas (1) to (3) are satisfied,
- Pj
-
- ≥
- 0
- .
- 9
- ×
-
- PbmL
- (
- 1
- )
- TszL
-
- ≥
- 0
- .
- 9
- ×
-
- TbmL
- (
- 2
- )
- TszH
- ≤
- 1.1
- ×
- TbmH
- ,
- (
- 3
- )
- where
- Pj is a maximum tensile load (N/mm) per unit joining length of the butt joint,
- PbmL is a smaller value (N/mm) between a product of a tensile strength (N/mm2) and a sheet thickness (mm) of the first steel sheet and a product of a tensile strength (N/mm2) and a sheet thickness (mm) of the second steel sheet,
- TszL is a minimum value (mm) of a thickness of the butt joint,
- TszH is a maximum value (mm) of the thickness of the butt joint,
- TbmL is a value (mm) of a thinner one between the sheet thickness of the first steel sheet and the sheet thickness of the second steel sheet, and
- TbmH is a value (mm) of a thicker one between the sheet thickness of the first steel sheet and the sheet thickness of the second steel sheet.
A tailor welded blank production method comprising
- pressing a pair of rotating tools facing each other into an unjoined portion, which is a butting portion between a first steel sheet and a second steel sheet, while rotating the rotating tools in opposite directions from each other from both sides of the unjoined portion, and
- moving the rotating tools in a joining direction, to thereby join the first steel sheet and the second steel sheet and obtain a tailor welded blank, wherein
- a diameter D (mm) of shoulders of the rotating tools satisfies the relationship according to the following formula (4), and
- RS×D3/JS, which is expressed by a rotational speed RS (rotations/minute) of the rotating tools, the diameter D (mm) of the shoulders of the rotating tools, and joining speed JS (mm/minute), satisfies the relationship according to the following formula (5),
- 4
- ×
- TJ
- ≤
- D
- ≤
- 10
- ×
- TJ
- (
- 4
- )
- 200
- ×
- TJ
- ≤
- RS
- ×
- D
- 3
- /
- JS
- ≤
- 2
-
- 0
-
- 00
- ×
- TJ
- ,
- (
- 5
- )
- where TJ is an average value (mm) of a sheet thickness of the first steel sheet and a sheet thickness of the second steel sheet.
Dependencies are inferred from the claim text.