Welded blank assembly and method

A welded blank assembly includes a capping material in a weld region of the assembly. The capping material can help protect a weld joint joining first and second sheet metal pieces together. At least one of the sheet metal pieces has a coating material layer that is removed prior to forming the weld joint so that the coating material does not contaminate the weld joint. The removed coating material can be collected before the weld joint is formed and reapplied as part of the capping material after the weld joint is formed, effectively changing the coating material from a potential weld contaminant to a weld joint protectant. The capping material may also include additional material from a source other than the coating material layer.

TECHNICAL FIELD

The present disclosure generally relates to welded blank assemblies and, more particularly, to welding coated sheet metal pieces together to form welded blank assemblies.

BACKGROUND

In an effort to improve resistance to corrosion, scaling and/or other processes, sheet metal made of high-strength or hardenable steel alloys are now being made with one or more thin coating material layers, such as aluminum- and zinc-based layers. Although these coating material layers can impart desirable qualities to the sheet metal, their presence can contaminate welds, thereby reducing weld strength, integrity, etc. This is particularly true if the coated sheet metal piece is being butt welded or lap welded to another sheet metal piece.

SUMMARY

According to one aspect, there is provided a welded blank assembly. The welded blank assembly comprises: first and second sheet metal pieces, at least one of the sheet metal pieces has a base material layer, a coating material layer, and an edge region with a weld notch where at least a portion of the coating material layer has been removed; a weld joint joining the first and second sheet metal pieces together at the edge region, the weld joint includes material from the base material layer but is substantially free of material from the coating material layer; and capping material that fills at least a portion of the weld notch. The capping material is in direct contact with the weld joint and becomes a permanent addition to the welded blank assembly.

According to another aspect, there is provided a welded blank assembly. The welded blank assembly comprises: first and second sheet metal pieces joined together, where at least one of the sheet metal pieces has a base material layer and a coating material layer; a weld joint that joins the first and second sheet metal pieces together along a weld region, the weld joint includes material from the base material layer but is substantially free of material from the coating material layer; and capping material that overlays at least a portion of the weld joint. The capping material includes material that was removed from the coating material layer before the weld joint was formed and was reapplied over the weld joint after the weld joint was formed.

According to another aspect, there is provided a method of making a welded blank assembly. The method may comprise the steps of: removing coating material from a region of a coated sheet metal piece; welding the sheet metal piece to another sheet metal piece so that a weld joint is formed in the region of the coated sheet metal piece, the weld joint includes base material from the sheet metal pieces but is substantially free of coating material; and applying capping material to the region of the coated sheet metal piece so that it covers at least a portion of the weld joint.

DETAILED DESCRIPTION

The welded blank assemblies disclosed herein are formed from sheet metal pieces, one or more of which have a weld notch formed along an edge region at an edge to be welded. The weld notch is characterized by the absence of certain constituents from the material layers. These sheet metal pieces, with material removed from the thin material layers along the edge region, can be used to form a welded blank assembly with a weld joint that is substantially free from one or more of the coating layer constituents. Material removed from the sheet metal pieces may be subsequently captured and reapplied or disposed over the weld joint so that it acts as a protectant rather than a contaminant.

Turning first toFIGS. 1A-C, there are shown some of the steps involved with manufacturing a conventional tailor-welded blank10that includes thick and thin sheet metal pieces12,12′ laser welded together in an edge-to-edge fashion. According to this example, each of the sheet metal pieces12,12′ has a base material layer14and multiple thin material layers16,18covering opposite surfaces of the base material layer. As is appreciated by those skilled in the art, there are numerous material layers that could be found on sheet metal stock, including various types of surface treatments, coating material layers such as aluminum-based and zinc-based material layers, oils and other oxidation preventing substances, contaminants from the manufacturing or material handling processes, and oxidation layers, to name but a few. Once the two sheet metal pieces are brought together in abutment, a laser beam or other welding tool is used to melt some of the sheet metal located in edge regions20,20′ so that a certain amount of the thin material layers16,18becomes embedded within the resulting weld joint22. Unless first removed, these unwanted constituents could have a negative impact on the overall strength and quality of the weld joint.

Referring toFIG. 2, there is shown an exemplary sheet metal piece12that may be formed and/or utilized by the present method and welded to an adjacent piece along an edge region20. The sheet metal piece12includes opposite first and second sides24,26, and the edge region20is located along an edge28that is to be welded. The particular edge region20shown inFIG. 2includes two weld notches30,30′. The two weld notches extend along the edge region20on opposite sides24,26of the sheet metal piece12. Each weld notch30,30′ is defined by a first notch surface32and a second notch surface34that intersect or join each other. Though shown with generally perpendicular first and second notch surfaces32,34along a single, straight edge region20, the weld notches may be configured in numerous ways. For example, a weld notch can: include one or more off-axis or offset notch surfaces, have a uniform or non-uniform depth and/or width, differ from other weld notches located on the same sheet metal piece in terms of size, shape, configuration, etc., or be part of an edge region located along a straight edge, a curved edge, multiple straight or curved edges, or some other part of the sheet metal piece, to cite several possibilities.

FIG. 3is a cross-section of the edge region20of the sheet metal piece12that is shown inFIG. 2. The illustrated sheet metal piece12includes multiple material layers, including the base material layer14, intermediate material layers16, and coating material layers18. In this embodiment, the base material layer14is the central or core material layer (e.g., a steel core) and is sandwiched between the intermediate material layers16and the coating material layers18. The base material layer14makes up the majority of the thickness T of the sheet metal piece12and thus may contribute significantly to the mechanical properties of the sheet metal piece. The coating material layers18are located over opposite surfaces of the base material layer14and are the outermost layers of the sheet metal piece12. Each coating material layer18is relatively thin with respect to the base material layer14and may be selected to enhance one or more characteristics of the sheet metal piece (e.g., corrosion resistance, hardness, weight, formability, appearance, etc.). The coating material layer18may also be selected for use or compatibility with subsequent processes, such as heat treatment or inter-diffusion processes, for example.

Each intermediate material layer16is located between the base layer14and one of the coating layers18, and each is in contact with the base and coating layers in this embodiment. The intermediate material layer16includes at least one constituent in common with each of the immediately adjacent layers14,18, such as an atomic element or chemical compound. The intermediate material layer16may be a reaction product of the base and coating material layers14,18. For example, a dip coating process, in which the base material layer is immersed or passed through a molten bath of the coating material, can result in a chemical reaction at the interface of the base material layer and the molten bath, and the reaction product is the intermediate material layer16. In one specific example of such a dip coating process, the base material layer14is steel and the coating material layer18is an aluminum alloy. The molten bath of aluminum alloy reacts with the base material layer at a base material layer surface to form the intermediate material layer16, which includes iron-aluminum (FexAly) intermetallic compounds such as Fe2Al5. The intermediate material layer16can have a higher content of the base material layer constituent (e.g., iron) in areas closer to the base material layer14, and a higher content of the coating material layer constituent (e.g., aluminum) in areas closer to the coating material layer18. Though shown inFIG. 3as a perfectly planar layer with a constant thickness, the intermediate material layer16may be irregular along its opposite surfaces as depicted in the enlarged view ofFIG. 4. The sheet metal piece12may include other, additional material layers as well, and is not limited to the particular arrangement described here.

One specific example of a multi-layered sheet metal piece that is useful for forming parts in the automotive and other industries is a coated steel product, such as that shown inFIG. 3. In one particular embodiment, the base material layer14is a high-strength or hardenable steel alloy such as a boron steel alloy or a high-strength low-alloy (HSLA) steel. Some materials, while strong for their weight, often require heat treating processes to attain the high-strength properties and/or can only be formed at high temperatures. The coating material layer18may be selected to help prevent oxidation during heat treatment and/or forming, to be lighter in weight than the base material layer14, and/or to interdiffuse with other layers of the sheet metal piece12during heat treatment. In one embodiment, the coating material layer18is pure aluminum (Al) or an aluminum alloy, such as an Al-silicone (Al—Si) alloy. Other possible compositions for coating material layer18include pure zinc and zinc alloys or compounds (e.g., where the underlying material is galvanized). Where the base material layer14is steel and the coating material layer18comprises aluminum, the intermediate material layer16may include iron and aluminum in the form of inter-metallic compounds such as FeAl, FeAl2, Fe3Al or Fe2Al5. The intermediate material layer16may also include an alloy of constituents from adjacent layers.

Some exemplary material layer thicknesses range from about 0.5 mm to about 2.0 mm for the base material layer14, from about 1 μm to about 15 μm for the intermediate layer16, and from about 5 μm to about 100 μm for the coating material layer18. Of course, these ranges are non-limiting, as individual layer thicknesses depend on several factors specific to the application and/or the types of materials employed. For example, the base material layer14can be a material other than steel, such as an aluminum alloy or some other suitable material, in which case the thickness may be outside of the above-described exemplary range. The method described herein may be used with sheet metal pieces having more or less material layers than shown in the figures. Skilled artisans will also appreciate that the figures are not necessarily to scale and that the relative thicknesses of layers14-18may differ from those illustrated in the drawings.

Referring again toFIG. 3, the weld notch30is a portion of the edge region20of the sheet metal piece12where some material has been removed or omitted from the otherwise uniform layered structure. The weld notch30promotes a high quality weld joint along edge28when the sheet metal piece is welded to another piece, and may do so via a configuration that reduces or eliminates the coating material layer18and/or the intermediate material layer16in the edge region20so that it does not become a part of a subsequently-formed weld joint. This is particularly useful where the coating material layer18includes one or more constituents that form discontinuities in or would otherwise weaken the resulting weld joint if included therein. The weld notch30has a notch width W and notch depth D, each being relatively constant along the length of edge28in this particular embodiment. The notch width W is the distance from edge28to the first notch surface32, and the notch depth D is the distance from the first side24(i.e., the outer surface of the coating material layer18) to the second notch surface34. Where the weld notch30is square with the sheet metal piece, as shown in this particular example, the notch width W is equal to the width of the second notch surface34and the notch depth D is equal to the depth of the first notch surface32. In the following discussion, the weld notch30on the first side24of the sheet metal piece is described. However, this description applies to the weld notch30′ on the opposite second side26of the sheet metal piece as well, when included as inFIG. 3.

The dimensions of the weld notch30may be related to the thickness T of the sheet metal piece, to the intended size of the weld joint to be formed at edge28, and/or to one or more material layer thicknesses. In one embodiment, notch width W is in a range from about 0.5 to about 1.5 times the thickness T. In another embodiment, the notch width W is in a range from about 0.5 mm to about 4 mm. The notch width W may also be at least one half of the width of the intended weld joint. The notch depth D for the example shown inFIG. 3is greater than the thickness of the coating material layer18and less than the combined thickness of the intermediate and coating material layers16,18, but this is not necessary and may differ in some of the other exemplary embodiments.

The weld notch30can also be described with relation to certain characteristics of the notch surfaces32,34. For example, in the embodiment ofFIG. 3, the first notch surface32includes material from both the intermediate material layer16and the coating material layer18. The second notch surface34includes material from the intermediate material layer16only, and the first and second notch surfaces intersect along a junction or corner36that is positioned or located in the intermediate material layer. Thus, in this particular example, the weld notch30is formed in the sheet metal piece12by removing the entire coating material layer18and a portion of the intermediate material layer16along edge region20. In other examples, the weld notch may be formed by removing only a portion of the coating material layer18, or by removing the entire coating and intermediate material layers18,16and a portion of the base material layer14. Each of the notch surfaces32,34may also include striations, witness lines, or other indicators of the type of process used to remove material at the weld notch location.

Referring now toFIG. 5, there is shown a process flow diagram for an exemplary method100of making a welded blank assembly. The illustrated method includes forming a weld notch along an edge region of a coated sheet metal piece (step102), collecting at least some of the material removed from the sheet metal piece during weld notch formation (step104), forming a weld joint that includes material from the sheet metal piece (step106), and subsequently disposing a capping material along the weld joint (step108). The capping material has a composition different from that of the base material layer of the sheet metal piece and different from that of the formed weld joint, and may include the coating material layer that was previously removed. In some embodiments, material from the coating material layer may be removed from the sheet metal piece prior to forming the weld joint, and then subsequently reapplied as part of the capping material, effectively transforming the coating material from a potential weld joint contaminant to a weld joint protectant. In the following figures, the described processes are only shown with respect to the first side24of the sheet metal piece(s). It should be understood that each of the illustrated processes or method steps may also be performed on the opposite side of the sheet metal pieces, even though not explicitly shown in the figures.

FIG. 6illustrates an exemplary embodiment of the present method. In this embodiment, steps102and104of the method are performed together. In particular, the weld notch30is formed by a laser ablation process, in which a laser beam50is directed at the edge region20of the sheet metal piece12along an ablation path52. A collection tool54may follow the laser beam along the ablation path and facilitates the deposition of a bead or ridge56of removed material alongside the ablation path52. In this example, the laser beam50and the sheet metal piece12move relative to one another, with the sheet metal piece stationary and the laser beam moving in the direction of arrow A (along the x-axis). In this example, the collection tool54is in the form of a disc that rotates about an axis B and rolls alongside the laser beam along the surface of the sheet metal piece12to act as a shield or backstop for the removed material. However, the collection tool could be any shape and/or non-rotating, such as a tool that slides along the sheet metal piece surface or a stationary tool that extends across the sheet metal piece in the direction of the ablation path52, so long as it collects, captures and/or otherwise gathers molten material that has been removed from the ablation path.

Laser ablation arrangements other than the specific example shown inFIG. 6are possible, and may include movement of the sheet metal piece, a different direction of relative movement, different component orientation (e.g., a vertically-oriented sheet metal piece), a non-linear ablation path, a non-orthogonal angle of laser beam incidence, or the use of multiple laser beams, to name a few variations. An ablation site or laser spot58is defined where the laser beam50impinges the sheet metal piece12. Light energy from the laser beam is converted to thermal energy at the laser spot58, and the outermost portion of the sheet metal piece at the laser spot is removed by vaporization and/or liquefication of the solid material. Where configured as a coated sheet metal piece as described above, the removed material includes at least some of the coating material layer18and optionally some of the intermediate and base material layers16,14. In this example, the laser spot58is generally rectangular due to the rectangular cross-section of the laser beam50, but other shapes (e.g., round, elliptical or composite shapes) are possible.

Referring now toFIG. 7, there is shown a cross-sectional view of the process illustrated inFIG. 6. The collection tool54is arranged alongside the laser spot58and functions as a shield of sorts to alter the normal trajectory of expulsed material60that may be ejected from the ablation site. For example, in some laser ablation processes, such as that shown inFIG. 7, at least some of the material removed from the sheet metal piece is expulsed from the ablation site while in a liquid or semi-liquid state. The extremely rapid local temperature changes that occur at the laser spot58may be accompanied by equally rapid local pressure changes, which can cause material in the fluid state to flow or otherwise be forced away from the ablation site. This may be particularly true where a pulsed laser is employed, such as high frequency nanosecond, picosecond, or femtosecond pulsed lasers. The expulsed material60may be in the form of droplets, as shown, that physically separate from the sheet metal piece, or it may remain in contact with the sheet metal piece and flow in a direction away from the ablation site58. In the absence of the collection tool54, the expulsed material may either splatter or flow or follow a trajectory to a cooler location along the sheet metal piece and farther from the ablation site, where it solidifies in some uncontrolled shape, configuration, and/or location. The collection tool54offers some control over these and other characteristics of the expulsed material60. In the illustrated example, the collection tool54keeps the expulsed material60on the weld notch side62of the tool. The expulsed material60is collected at the sheet metal piece surface alongside the weld notch30in the form of an elongated bead or ridge56, which comprises material from the coating material layer18in this example and can be subsequently reused by the method, as will be explained.

The collection tool54may include a profile64to exercise further control over the deposition of the expulsed material60. As shown in the example ofFIG. 8, the profile64is located on the weld notch side62and at the periphery of the collection tool. The illustrative profile64includes a curved surface that helps define the shape of the resulting bead56of material. The shape of the profile64may or may not be the same as the intended cross-sectional shape of the bead56. For example, the profile64may also function to redirect expulsed material60toward the sheet metal piece surface—i.e., the curved shape of the illustrated profile64is configured to not only interrupt the normal trajectory of the expulsed material, but also to redirect it toward the sheet metal piece and the desired location of bead56. Depending at least partly on whether the expulsed material flows along the sheet metal surface during the ablation process or loses contact with the sheet metal surface in the form of droplets as shown, not all of the material removed by the laser is necessarily deposited as part of the bead56of material. For example, some of the expulsed material60may be vaporized, some of the expulsed material may be ejected from the ablation site58in the direction of edge28and/or some of the expulsed material may stick to the collection tool54at a location away from the bead56location. In one embodiment, the collection tool is constructed from or has a surface coating comprising a non-stick material such as PTFE or other low surface energy material(s). In other embodiments, a wire brush or other cleaning tool may be used to remove excess expulsed material from the collection tool.

The step of collecting removed material may also include the use of a pressurized gas, such as air, one or more shielding gases, or some other fluid, as shown inFIG. 9, for example. In this example, a gas nozzle66directs a jet of gas68at the ablation site and toward the collection tool54in order to influence the material expulsion process. The jet of gas68can simultaneously cool the newly formed weld notch and/or bead56of material while directing expulsed material60toward the collection tool and/or toward the desired bead location. As shown, more of the expulsed material60, such as expulsed material that would otherwise be ejected from the ablation site toward edge28, can be collected by the tool54and deposited along the formed weld notch30as part of bead56. Of course, more than one jet68of gas or other fluid may be employed, and the pressure, flow rate, and direction of each jet can be customized for each application, depending on the desired shape and/or location of bead56.

In the example ofFIG. 10, the collection tool54′ itself is a gas nozzle or other pressurized fluid source that alters the trajectory of the expulsed material60without the need for a solid physical barrier. In this example, opposing jets of gases68,70are used together to control the location of bead56. Each jet of gas or other fluid68,70may have independently controlled direction, pressure, velocity, flow rate, temperature, composition, profile shape (e.g., different shaped nozzle openings) and/or other parameters.

In another example, not shown, a non-rotary collection tool in the form of a shield may be used alongside the laser spot58in order to manipulate the normal trajectory of expulsed material and help form the resulting bead56. The features mentioned above, like the profiled surface64and the pressurized air or shielding gas, may be used with this embodiment as well.

With reference now toFIG. 11, there is shown an exemplary welding process for forming a welded blank assembly200from two coated sheet metal pieces12,112. One or both of the sheet metal pieces12,112may include a bead56of material comprising coating layer material that has been removed, collected, and deposited along respective weld notches30in previous operations. In the illustrated process, the edge regions20of the two sheet metal pieces12,112are aligned with respective edges28butted together. A high-powered laser beam202for welding is directed toward the aligned edge regions20and impinges the sheet metal pieces12,112at a laser spot204. The laser beam202delivers energy to the laser spot204that is sufficient to locally melt material from each of the sheet metal pieces12,112, thereby forming a weld pool206that includes molten material from both sheet metal pieces, preferably from both base material layers. As the laser beam202moves forward or advances along the aligned edge regions20in direction A (in the negative x-direction inFIG. 11), the portion of the weld pool206behind the laser beam (in the positive x-direction) solidifies to form a weld joint208. The resulting weld joint208joins the two sheet metal pieces12,112and is located in a weld region220of the welded blank assembly200. Of course, it is possible for the two sheet metal pieces12,112to move instead of or in addition to the laser beam202, so long as there is relative movement between the work pieces and the laser.

The weld joint208may be substantially free of material from at least one of the coating material layer(s). This is due at least in part to the weld notches30being provided along the respective edge regions20, where material from the coating layer(s) has been removed. In this particular example, each of the illustrated sheet metal pieces12,112has a different thickness (i.e., assembly200is a tailor welded blank) and is prepared with weld notches30formed along opposite sides24,26of the respective edge region20. It is also noted that, although the illustrated blank assembly200includes a single weld joint208, the welded blank assembly may be formed from more than two sheet metal pieces with more than one weld joint. The blank assembly200may alternatively or additionally include one or more curvilinear weld joints, in which at least a portion of the weld joint208is curve-shaped and formed along curved or contoured edges28and/or edge regions20.

FIGS. 12 and 13show examples of processes, one or both of which may be included as part of step108ofFIG. 5to dispose a capping material210along or over the weld joint208. In these examples, the expulsed material that was collected at beads56is now being reheated and used as capping material210to at least partially cover and protect the weld joint from oxidation, corrosion, etc. With reference toFIG. 12, there is shown welded blank assembly200in contact with a pair of reapplication tools212configured to displace the beads56of material toward the weld joint208. The reapplication tools212in this example are rollers, but they could be non-rotary shields or any other suitable tool capable of redirecting or disposing the previously collected coating material towards the weld joint. Each roller has a rotational axis C, and in the illustrated example, the rollers212are oriented so that the rotational axes are non-perpendicular with the direction of relative movement of the blank assembly200and the rollers. The weld joint side214and/or the periphery216of each roller displaces material from the beads56toward the weld joint208as shown. In this example the rollers212remain in one place while the blank assembly200is moved beneath them in the direction of the unnumbered arrows, but the blank assembly could remain stationary with the rollers moving instead or there could be a series of rollers that progressively work together to displace the material. The blank assembly may be supported by additional rollers or other means (not shown) at its opposite side26. This is only one example of a process for disposing the capping material210along or over the weld joint208. In other embodiments, the reapplication tool(s) may include a stationary block having a continuously decreasing amount of space between the block and the blank assembly as the blank assembly passes beneath the block, thereby compressing the beads56of material and displacing the material toward the weld joint.

Depending on the dimensions of the weld notches30, the amount of collected material present in beads56, and other factors, the capping material210may partially cover the weld joint208, entirely cover the weld joint, or be disposed alongside the weld joint without covering any portion thereof. In the example ofFIG. 12, the reapplication tools212displace the beads56so that the capping material210covers or overlies the widthwise edges of the weld joint208. In another embodiment, capping material may be coated over or along the weld joint208from a source other than the material beads56. For example, capping material in powder form may be deposited along the weld joint immediately after the weld joint is formed and while the weld joint is still sufficiently hot to partly or fully liquefy the capping material so the capping material can flow and partially or fully cover the weld joint208. Other sources of capping material are possible instead of, or in addition to, the beads56of material.

In one embodiment, a portion of the capping material210is material collected by the collection tool during the above-described coating removal process, and another portion of the capping material is additional material from a different source. The additional material can have the same composition as the coating material layer, or it can have a composition different from the coating material layer. The additional material can be provided as a molten material, a powder material, a spray-on or brush-on material, an extruded material, a film of material, or in any other suitable form. The additional material may be layered over the collected and reapplied material from the coating material layer, fill the remainder of the weld notch not filled by the reapplied material, cover the portion of the weld joint not covered by the reapplied material, or any combination thereof. In some cases the capping material may include only additionally provided material and does not include collected and reapplied material from the coating material layer. The capping material210may also be characterized as becoming a permanent addition to the welded blank assembly, thus distinguishing such embodiments from temporary weld joint protectants that are burned away or otherwise removed during subsequent processes such as metal forming and finishing processes. In some cases, the capping material has a material composition intended to change the weld joint composition or microstructure in subsequent processes. In one particular example, the capping material has a composition that may include aluminum, aluminum alloys, zinc, zinc alloys, organic or non-organic coatings, or any other corrosion protecting coatings, and can be designed for interdiffusion with the weld joint material during a subsequent heat treating and/or hot forming process.

With reference toFIG. 13, the blank assembly200ofFIG. 12is shown passing beneath a heat source218. The heat source218is configured to supply sufficient thermal energy to the capping material210to cause it to flow and cover the weld joint208. In this example, the heat source218is stationary, and the blank assembly200moves beneath the heat source, but other relative movement is possible. The heat source218may be an infrared heat source, conduction heat source, induction heat source, laser energy heat source, or any other suitable heat source. In this example, the blank assembly200is subjected to the heat source218after the beads56of material ofFIGS. 11 and 12are displaced along the weld joint208. In another embodiment, the blank assembly200is subjected to the heat source218before or during the time the beads56of material ofFIGS. 11 and 12are displaced along the weld joint208and may serve to soften the beads of material to allow them to be more easily displaced or to more readily flow along and/or over the weld joint. In another embodiment, the reapplication tools212ofFIG. 12may be omitted and the heat source218is the reapplication tool, sufficiently heating the beads of material to cause the material to flow into the weld notches and along and/or over the weld joint208without the need for mechanical displacement of the beads56. In yet another embodiment, the heat source218is the same heat source used to heat the welded blank assembly200to an elevated forming temperature at which the blank assembly is formed into a desired shape. For instance, in certain hot-forming processes, the blank assembly may be heated to an elevated temperature prior to forming, and the elevated temperature may be sufficient to cause the beads of material to flow along the weld joint. In another example, the heat source218is the same heat source used to heat the welded blank assembly to diffusion or heat-treating temperature at which the coating material layer interdiffuses with the base material layer. The blank assembly can also be oriented at an inclined angle or oriented vertically while subjected to the heat source218so that gravity can be used to aid material flow.

FIG. 14illustrates a continuous process for making a welded blank assembly, shown in a plan view. The illustrated process corresponds to method steps106-108ofFIG. 5. Here, two coated sheet metal pieces12,112are arranged with respective edge regions20aligned and with edges28butted together. Each sheet metal piece12,112includes a bead56of material comprising coating layer material that has been removed, collected, and deposited along the respective weld notches30in previous operations. The sheet metal pieces12,112are fed together in the direction of the unnumbered arrows (the x-direction). In sequence, the sheet metal pieces12,112are laser welded together via laser beam202, then the beads of material56are displaced toward the formed weld joint208as the capping material210by reapplication tools212while the material is still heated and softened by the laser beam202. Subsequently, the weld region220passes beneath heat source218to cause the capping material to flow and cover the weld joint208. This is only one example of a continuous process, as one or more steps may be omitted or additional steps may be added. For example, heat sources218may be arranged before, after and concurrent with the reapplication tools212, capping material210may be supplied from an alternative or additional source from the material beads56, etc.

FIG. 15is a cross-sectional view of an exemplary weld region220of the welded blank assembly200after the capping material210is disposed over the weld joint208. The capping material210covers and/or protects the base material layer or intermediate material layer otherwise exposed by formation of the weld notches, as well as covering and/or protecting the weld joint208, which is largely composed of the base material layer. In this example, the sheet metal pieces that are joined to form the blank assembly200have the same thickness, but the joined pieces may have different thicknesses as well, as inFIGS. 11-13.