Abstract: A method of laser welding together two or more overlapping metal workpieces (12, 14 or 12, 504, 14) that define a welding region (16) in which at least a portion of an accessible top surface (20, 120, 220, 520) of a workpiece stack-up (10, 110, 210, 510) is curved or angled includes advancing a laser beam (24) along a beam travel pattern (74) that at least partially lies on the portion of the top surface that is curved or angled while maintaining a constant focal distance (64) of the laser beam during such advancing travel. The beam travel pattern may be projected onto a curved portion (20?, 220?) of the top surface, an angled portion (120?) of the top surface, or two or more portions (20?, 20?, 120?, 120?, 220?, 220?, 220??) of the top surface that lack planarity.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method of laser welding a workpiece stack-up (10) that includes at least two overlapping aluminum workpieces (12, 14) comprises advancing a laser beam (24) relative to a plane of a top surface (20) of the workpiece stack-up (10) and along a spot weld travel pattern (74) that includes one or more nonlinear inner weld paths and an outer peripheral weld path that surrounds the one or more nonlinear inner weld paths. Such advancement of the laser beam (24) along the spot weld travel pattern (74) translates a keyhole (78) and a surrounding molten aluminum weld pool (76) along a corresponding route relative to the top surface (20) of the workpiece stack-up (10). Advancing the laser beam (24) along the spot weld travel pattern (74) forms a weld joint (72), which includes resolidified composite aluminum workpiece material derived from each of the aluminum workpieces (12, 14) penetrated by the surrounding molten aluminum weld pool (76), that fusion welds the aluminum workpieces (12, 14) together.

Abstract: A method of laser welding a workpiece stack-up (10) that includes at least two overlapping aluminum workpieces (12, 14), at least one of which includes a protective anti-corrosion coating (38), is disclosed. The disclosed method includes advancing the laser beam (56) relative to the top surface (26) of the workpiece stack-up (10) along a travel path (78, 78?, 78?, 78??) that imposes bidirectional movement of the laser beam (56). In particular, the laser beam (56) moves in a forward direction (80) while also moving back and forth in a lateral direction (82) oriented transverse to the forward direction (80) as it is being advanced relative to the top surface (26). Such bidirectional movement is believed to help disturb the protective anti-corrosion coating (38) in and around the molten aluminum weld pool (74), thus leading to a laser weld joint (68) that contains less weld defects derivable from the protective anti-corrosion coating(s) (38).

Abstract: A method of laser welding a workpiece stack-up (10) that includes at least two overlapping steel workpieces (12, 14) comprises directing a laser beam (40) at a top surface (26) of the workpiece stack-up to form a keyhole (56) surrounded by a molten steel weld pool (58). The laser beam is conveyed along a predefined weld pattern that includes one or more nonlinear inner weld paths (66) and an enclosed outer peripheral weld path (68) 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 (28) 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.

Abstract: 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.

Abstract: 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.

Abstract: A method of laser welding a workpiece stack-up includes directing a laser beam at a top surface of a first metal workpiece to form a key-hole that entirely penetrates the workpiece stack-up, including an underlying second metal workpiece, so that the keyhole reaches a bottom surface of the second metal workpiece. A zone of negative pressure established under the bottom surface of the second metal workpiece extracts vapors that are produced by the laser beam. The vapors, in particular, are extracted from the bottom surface of the second metal workpiece through the keyhole. A bottom workpiece holder that supports the bottom metal workpiece during laser welding may be constructed to establish the zone of negative pressure.

Abstract: Systems and methods for performing simple and quick real time single music note recognition algorithm based on fuzzy pattern matching are disclosed. In one aspect, the systems and methods use a 256-point FFT and fuzzy pattern identification and recognition method. The systems and methods can recognize a note as short as 0.125 seconds in a frequency range from 16 Hz to 4000 Hz, with 11.025 KHz sampling rate and 8-bit per sampling signal. The systems and methods may be used as part of a music tutor system that receives a played note, identifies the played note, and compares the played note with a reference note. An indication may be given as to whether the played note matched the reference note.

Abstract: Systems and methods for performing simple and quick real time single music note recognition algorithm based on fuzzy pattern matching are disclosed. In one aspect, the systems and methods use a 256-point FFT and fuzzy pattern identification and recognition method. The systems and methods can recognize a note as short as 0.125 seconds in a frequency range from 16 Hz to 4000 Hz, with 11.025 KHz sampling rate and 8-bit per sampling signal. The systems and methods may be used as part of a music tutor system that receives a played note, identifies the played note, and compares the played note with a reference note. An indication may be given as to whether the played note matched the reference note.