Gm Global Technolgoy Operations, Inc.

Wu Tao

David S Yang

Yu Pan

Li Sun

Blair E Carlson

Qi Lu

Justin Allen Wolsker

Paolo A Novelletto

Haijing Liu

Jing Jing Zhang

Dalong Gao

Xiaochao Que

Jeffrey A Abell

Hui-ping Wang

Teresa J Rinker

Joshua L Solomon

Charles M Enloe

Curt D Horvath

William P Payne

A method of laser welding together two or more overlapping metal workpieces (, or) included in a welding region () of a workpiece stack-up () involves advancing a beam spot () of a laser beam () relative to a top surface () of the workpiece stack-up along a first weld path () in a first direction () to form an elongated melt puddle () and, then, advancing the beam spot () of the laser beam () along a second weld path () in a second direction () that is opposite of the first direction while the elongated melt puddle is still in a molten state. The first weld path and the second weld path overlap so that the beam spot of the laser beam is conveyed through the elongated melt puddle when the beam spot is advanced along the second weld path.

Method for laser welding metal workpieces using a combination of weld paths

A method for joining together metal workpiece (or) includes forming a laser weld joint () in a workpiece stack-up () that fusion welds two or more overlapping metal workpiece (oror) together. The laser weld joint () has an initial top surface (). Once the laser weld joint () is formed, the method calls for impinging the laser weld joint () with a laser beam () and moving the laser beam () along the initial joint () including the initial top surface (). The laser beam () is eventually removed from the laser weld joint () to allow the melted upper portion () of the joint () to resolidify and provide the laser weld joint () with a modified top surface () that is smoother than the initial top surface (). By providing the laser weld joint with a smoother modified top surface, residual stress concentration points are removed and the laser weld joint is less liable to damage seal strips.

Method for smoothing the surface of a laser weld joint

A device and associated method for joining, via a laser welder, a first workpiece to a second workpiece is described. This includes arranging the first and second workpieces in a stack, including overlapping a portion of the first workpiece with a portion of the second workpiece. The laser welder generates a first laser beam and coincidentally controls the laser welder to traverse a desired weld path that is disposed on the top surface of the first workpiece. The laser devices generates a second laser beam and coincidentally controls the laser welder to traverse the desired weld path. Generating, via the laser welder, the first laser beam includes operating the laser welder at a pulsed operation and at a first power level. Generating, via the laser welder, the second laser beam includes operating the laser welder at a continuous operation and at a second power level.

Method and apparatus for laser welding

A method of laser spot welding a workpiece stack-up () that includes at least two overlapping steel workpieces () is disclosed. The method includes directing a plurality of laser beams (&#x2033;) at the top surface () of the workpiece stack-up to create a molten steel weld pool () that penetrates into the stack-up. The molten steel weld pool is then grown to penetrate further into the stack-up by increasing an overall combined irradiance of the laser beams while reducing the total projected sectional area () of the laser beams at a plane of the top surface of the workpiece stack-up. Increasing the overall combined irradiance of the laser beams may be accomplished by moving the focal points (&#x2033;) of the laser beams closer to the top surface or by reducing the mean angle of incidence () of the laser beams so as to reduce the eccentricity of the individual projected sectional areas of the laser beams.

Multi-beam laser spot welding of coated steels

A method for laser welding a plurality of battery foils to a battery tab that does not include ultrasonic welding and includes clamping the plurality of battery foils and the battery tab together. Each of the plurality of battery foils has a thickness that is between 0.004 millimeters and 0.03 millimeters. The battery tab has a thickness that is between 0.1 millimeters and 0.5 millimeters. The method further includes laser welding the plurality of battery foils to the battery tab.

Clamping system and method for laser welding battery foils to a battery tab

A method of laser spot welding a workpiece stack-up that includes at least two overlapping steel workpieces, at least one of which includes a surface coating, is disclosed. The method includes directing a laser beam at the top surface of the workpiece stack-up to create a molten steel weld pool that penetrates into the stack-up. The molten steel weld pool is then grown to penetrate further into the stack-up by increasing an irradiance of the laser beam while reducing the projected sectional area of the laser beam at a plane of the top surface of the workpiece stack-up. Increasing the irradiance of the laser beam may be accomplished by moving a focal point of the laser beam closer to the top surface or by reducing an angle of incidence of the laser beam so as to reduce the eccentricity of the projected sectional area of the laser beam.

Method of laser spot welding coated steels

A method of laser welding a workpiece stack-up () of overlapping steel workpieces () involves heat-treating a region () of the stack-up () followed by forming a laser weld joint () that is located at least partially within the heat-treated region (). During heat-treating, one or more pre-welding laser beams () are sequentially directed at a top surface () of the workpiece stack-up () and advanced along a pre-welding beam travel pattern () so as to reduce an amount of vaporizable zinc within the stack-up (). Thereafter, the laser weld joint () is formed by directing a welding laser beam () at the top surface () of the workpiece stack-up () and advancing the welding laser beam () along a welding beam travel pattern () that at least partially overlaps with a coverage area of a pre-welding beam travel pattern () or a shared coverage area portion of multiple pre-welding beam travel patterns (). The method can help reduce an amount of vaporizable zinc within the stack-up ().

Method for laser welding steel workpieces

A method of laser welding a workpiece stack-up () that includes at least two overlapping metal workpieces () comprises advancing a laser beam () relative to a plane of a top surface () of the workpiece stack-up () from a start point () to an end point () along a beam travel pattern () at a high laser beam travel speed of greater than 8 meters per minute. The two or more overlapping metal workpieces () may be steel workpieces or they may be aluminum workpieces, and at least one of the metal workpieces () includes a surface coating (). Advancing the laser beam () along the beam travel pattern () forms a weld joint (), which includes resolidified composite workpiece material derived from each of the metal workpieces () penetrated by a molten weld pool (), that fusion welds the metal workpieces () together. The relatively high laser beam travel speed contributes to improve strength properties of the weld joint ().

Remote laser welding of overlapping metal workpieces at fast speeds

A method of laser welding a workpiece stack-up () that includes at least two overlapping aluminum workpieces comprises advancing a laser beam () relative to a plane of a top surface () of the workpiece stack-up () and along a beam travel pattern () that lies within an annular weld area () defined by an inner diameter boundary () and an outer diameter boundary () on the plane of the top surface (). The beam travel pattern () of the laser beam () surrounds a center area encircled by the annular weld area () on the plane of the top surface () so as to force entrained porosity inwards into a region of the weld joint () beneath the center area on the plane of the top surface () of the workpiece stack-up ().

Laser spot welding of overlapping aluminum workpieces

A method of laser welding a workpiece stack-up () that includes at least two overlapping steel workpieces () comprises directing a laser beam () at a top surface () of the workpiece stack-up to form a keyhole () surrounded by a molten steel weld pool (). The laser beam is conveyed along a predefined weld pattern that includes one or more nonlinear inner weld paths () and an enclosed outer peripheral weld path () surrounding the one or more nonlinear inner weld paths. During conveyance of the laser beam along the one or more nonlinear inner weld paths, the keyhole fully penetrates through the workpiece stack-up from the top surface of the stack-up to the bottom surface () of the stack-up. The method produces weld joints between the steel workpieces that do not have an intentionally imposed gap formed between their faying surfaces.

Laser welding overlapping metal workpieces

A method of resistance spot welding a workpiece stack-up comprising overlapping first and second steel workpieces is disclosed, wherein at least one of the steel workpieces comprises an advanced high-strength steel substrate. The workpiece stack-up is positioned between a pair of opposed first and second welding electrodes. A cover is disposed between at least one of the first steel workpiece and the first welding electrode or the second steel workpiece and the second welding electrode at an intended weld site. The workpiece stack-up is clamped between the first and second welding electrodes at the weld site such that at least one of the weld faces of the first and second welding electrodes presses against the cover. The first and second steel workpieces are welded together by passing an electrical current between the first and second welding electrodes at the weld site.

Method and apparatus for resistance spot welding overlapping steel workpieces

A method of laser welding a workpiece stack-up that includes two or more overlapping metal workpieces is disclosed. The disclosed method includes directing a laser beam at a top surface of the workpiece stack-up to create a molten metal weld pool and, optionally, a keyhole, and further gyrating the laser beam to move a focal point of the laser beam along a helical path having a central helix axis oriented transverse to the top and bottom surfaces of the workpiece stack-up. The gyration of the laser beam may even be practiced to move the focal point of the laser beam along a plurality of helical paths so as to alternately convey the focal point back-and-forth in a first overall axial direction and a second overall axial direction while advancing the laser beam relative to the top surface of the workpiece stack-up along a beam travel pattern.

Remote laser welding of overlapping metal workpieces using helical path(s)

A multilayer steel includes a core formed of transformation-induced plasticity (TRIP) steel. A decarburized layer is exterior to the core on at least one side thereof. The decarburized layer has reduced carbon content relative to the core. A zinc-based layer is exterior to the decarburized layer. The decarburized layer may have a composition of at least 80 percent ferrite, such that LME is reduced or mitigated. In some configurations, the decarburized layer is between 10-50 microns thick. A method of creating a coated advanced high-strength steel component is also provided. An apparatus for forming a coated advanced high-strength steel is also provided. The core of the multilayer steel may have a carbon weight-percent of less than or equal to 0.4. The decarburized layer of the multilayer steel may have a carbon weight-percent of less than or equal to 50 percent of the carbon weight-percent of the core.

Multilayer steel and method of reducing liquid metal embrittlement

A method of laser welding a workpiece stack-up that includes at least two overlapping metal workpieces is disclosed. The method includes advancing a beam spot of a laser beam relative to a top surface of the workpiece stack-up and along a beam travel pattern to form a laser weld joint, which is comprised of resolodified composite metal workpiece material, that fusion welds the metal workpieces together. And, while the beam spot is being advanced along the beam travel pattern, between a first point and a second point, which may or may not encompass the entire beam travel pattern, at least one of the following laser beam parameters is repeatedly varied: (1) the power level of the laser beam; (2) the travel speed of the laser beam; or (3) the focal position of the laser beam relative to the top surface of the workpiece stack-up.

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Tianmen, China

Wu Tao