Hot stamped components with tailored properties and method of forming the same

Abstract

A method for forming a part that has tailored tempered properties is provided. The method comprises: receiving a blank of steel material having a high emissivity coating on at least one side thereof; removing a portion of the high emissivity coating (HEC) from portions of the blank; heating the blank in a furnace, wherein the regions of the blank having the HEC thereof remaining thereon are heated more quickly in the furnace than the portions where the HEC has been removed; and quenching the blank after said heating such that martensite is formed in regions of the blank at which the HEC was not removed. Less martensite is formed in regions of the blank at which HEC was removed.

Description

OF FORMING THE SAMECROSS-REFERENCE TO RET TED APPLICATION(S)

[0001] This patent application claims priority, under 35 U.S.C. § 119(e), to U.S. Provisional Patent Application Serial No. 63 / 527,797, filed July 19, 2023, titled “HOT STAMPED COMPONENTS WITH TAILORED PROPERTIES AND METHOD OF FORMING THE SAME,” which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Creating tailored tempered hot stamped metal components is challenging and costly. Various technologies may be used such as in-die heating, induction heating, and in-line thermal printing, which all require significant capital investment.

[0003] For in-die heating, heater cartridges are inserted in the tooling to create a die that can slow the cooling rate during quench, resulting in non-martensitic phase transformations.

[0004] Thermal in-line printing technology employs a device which cools the blank in the furnace to a temperature so that when it exits the furnace it is below the AC3 temperature (generally speaking, the temperature at which transformation of ferrite to austinite is complete during heating) resulting in non-fully martensitic phase transformation.

[0005] For post process annealing, parts are sent to an offline station where it is heated to produce tempered martensite and / or other softer phases for the purpose of creating different physical properties (e.g., hardness levels).

[0006] The present disclosure pertains to a cost-effective method of forming a tailor tempered part in which a blank goes through a traditional hot stamp furnace and can be stamped in a standard hot forming die to produce a hot stamped component having the tailored tempered properties.SUMMARY

[0007] The present patent application relates to systems and methods for forming a part that has tailored tempered properties.

[0008] In one embodiment, the method comprises receiving a blank of steel material having a high emissivity coating on at least one side thereof; removing a portion of the high emissivity coating (HEC) from portions of the blank; heating the blank in a furnace, wherein the regionsof the blank having the HEC thereof remaining thereon are heated more quickly in the furnace than the portions where the HEC has been removed; and quenching the blank after the heating such that martensite is formed in regions of the blank at which the HEC was not removed, and wherein less martensite is formed in regions of the blank at which HEC was removed.

[0009] In one embodiment, a coating of aluminum or an aluminum alloy (such as AlSi) is disposed on the blank of steel material and underlies the HEC, and the removing removes only the HEC without removing the aluminum or aluminum alloy coating. It is noted that in some embodiments, some removal of the aluminum or aluminum alloy may be removed, but not all of it.

[0010] In one embodiment, no martensite is formed in regions of the blank where the HEC was removed.

[0011] In one embodiment, the removing is performed by laser ablation of the HEC. In one embodiment, the removing is performed by chemical treatment.

[0012] In one embodiment, the removing is performed by etching with an acid material.

[0013] In one embodiment, removing is performed by rubbing ethanol on the HEC.

[0014] In one embodiment, HEC is provided on opposite sides of the blank of steel material.

[0015] In one embodiment, just a portion of the aluminum or aluminum alloy coating is removed as a result of the removal of the HEC.

[0016] In one embodiment, wherein none of the aluminum or aluminum alloy is removed as a result of the removal of the HEC.

[0017] In one embodiment, there is provided a method for forming a part that has tailored tempered properties, comprising butt welding a first blank of steel material to a second blank of steel material to form a blank assembly, the second blank of steel material having a high emissivity coating (HEC) on at least one side thereof; heating the blank assembly in a furnace, wherein portions of the blank assembly having the HEC thereon are heated more quickly than portions of the blank assembly without the HEC thereon; and quenching the blank assembly after heating such that martensite is formed in regions of the blank assembly with the HEC thereon, and wherein less martensite is formed at regions of the blank assembly that did not have HEC thereon when heated in the furnace.

[0018] In one embodiment, a portion of the HEC is removed from the second blank prior to heating the blank assembly.

[0019] In one embodiment, the second blank has a coating of AlSi is disposed on the blank of steel material, underlying the HEC, and the removing of the HEC removes only the HEC without removing all of Al Si coating.

[0020] In one embodiment, the removing is performed prior to butt welding. In one embodiment, the removing is performed after butt welding.

[0021] In another embodiment, there is provided a method for forming a pillar member for a vehicle, comprising receiving a blank of steel material having a high emissivity coating on at least one side thereof; removing a portion of the high emissivity coating (HEC) from portions of the blank that are to be formed into a lower, larger dimensioned portion of the B-pillar in relation to at least one upper portion of the B-pillar; heating the blank in a furnace, wherein the regions of the blank having the HEC thereof are heated more quickly than the portions where the HEC has been removed; quenching the blank after heating such that martensite is formed in regions of the blank at which the HEC was not removed, and wherein less martensite is formed in regions of the blank at which HEC was removed; and stamping and trimming the blank so as to provide the blank with a pillar configuration, and wherein the lower, larger dimensioned portion is softer than the at least one upper portion of the B-pillar.

[0022] In another embodiment, there is provided a method for forming a pillar member for a vehicle, comprising receiving a blank of steel material having a high emissivity coating on at least one side thereof; removing a portion of the high emissivity coating (HEC) from portions of the blank that are to be formed into an edge portion of the B-pillar that is to be formed into a flange portion of the pillar member; heating the blank in a furnace, wherein the regions of the blank having the HEC thereof are heated more quickly than the portions where the HEC has been removed; quenching the blank after heating such that martensite is formed in regions of the blank at which the HEC was not removed, and wherein less martensite is formed in regions of the blank at which HEC was removed; and stamping and trimming the blank so as to provide the blank with a pillar configuration having the flange portion, and wherein the flange portion is softer than the at least one other portion of the B-pillar.

[0023] In another embodiment of the present patent application, a method for forming a part that has tailored tempered properties is provided. The method comprises heating a blank of steel material in a furnace, the blank having a high emissivity coating (HEC) on some regions thereof and devoid of the HEC on other regions thereof; forming the blank and quenching the blank in a forming die, after said heating, such that martensite is formed in regions of the formed blank that had the HEC and regions of the formed blank that were devoid of the HECare non-martensitic; and trimming and / or piercing the non-martensitic portions of the formed blank in the forming die.

[0024] In one embodiment, the formed blank includes a pillar member.

[0025] In one embodiment, the formed blank includes a B-pillar.

[0026] In one embodiment, the formed blank includes edges having the non-martensitic portions. In one embodiment, after the forming and the quenching procedures, the trimming is configured to trim the non-martensitic portions of the edges of the formed blank.

[0027] In one embodiment, after the forming and the quenching procedures, the piercing is configured to punch holes in the non-martensitic portions of the formed blank.

[0028] In one embodiment, the non-martensitic portions of the formed blank are softer than the martensitic portions of the formed blank.

[0029] In one embodiment, prior to the heating the blank, removing the HEC from portions of the blank to create the regions of the blank that are devoid of the HEC.

[0030] These and other aspects of the present patent application, as well as the methods of operation and functions of the related elements of structure and the combination of parts and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, wherein like reference numerals designate corresponding parts in the various figures. In one embodiment of the present patent application, the structural components illustrated herein are drawn to scale. It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the present patent application. It shall also be appreciated that the features of one embodiment disclosed herein can be used in other embodiments disclosed herein. As used in the specification and in the claims, the singular form of “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0031] Other aspects, features, and advantages of the present patent application will become apparent from the following detailed description, the accompanying drawings, and the appended claims.

[0032] Each of the aspects described above and in the following description can be used in any combination of one or more of these aspects, as will be understood to a person of ordinary skill in the art.BRIEF DESCRIPTION OF DRAWINGS

[0033] FIG. 1 shows a graph with heating profiles of blanks with and without high emissivity coating (HEC) in accordance with an embodiment of the present patent application;

[0034] FIG. 2 shows a B-pillar of a vehicle in accordance with an embodiment of the present patent application, wherein a relatively softer pillar area of the B-pillar (with the HEC removed therefrom prior to entering the furnace) and a relatively harder area of the B-pillar (with the HEC remaining therein prior to being placed in the furnace) are shown;

[0035] FIG. 3 shows a B-pillar of a vehicle in accordance with another embodiment of the present patent application, wherein relatively softer vehicle pillar flanges (with the HEC removed therefrom prior to entering the furnace) and a relatively harder area of the B-pillar (with the HEC remaining therein prior to being placed in the furnace) are shown;

[0036] FIG. 4 shows a floor pan of a vehicle in accordance with an embodiment of the present patent application, wherein a relatively softer area of the floorpan (with the HEC removed therefrom prior to entering the furnace), a relatively harder area of the floorpan (with the HEC remaining therein prior to being placed in the furnace), and a transition area of the floorpan are shown;

[0037] FIGS. 5 and 6 show various physical attributes and properties of Al Si regions (where the HEC has been removed from the substrate blank prior to being placed in the furnace) and HEC regions (where the HEC was not removed from the substrate blank prior to being placed in the furnace) in accordance with an embodiment of the present patent application;

[0038] FIG. 7A shows a HEC layer provided directly on a substrate blank, and FIG. 7B shows portions of the HEC layer are removed from the substrate blank in accordance with an embodiment of the present patent application;

[0039] FIG. 8A shows a substrate blank that is pre-coated on at least one side thereof with at least one layer of aluminum or aluminum alloy and a HEC layer is coated on top of that aluminum or aluminum alloy precoating, and FIG. 8B shows portions of the HEC layer are removed from the top of that aluminum or aluminum alloy precoating in accordance with an embodiment of the present patent application;

[0040] FIG. 9 shows a shaping / forming die system with a trim system in accordance with an embodiment of the present patent application;

[0041] FIG. 10 shows a portion of the shaping die system with a piercing / punch system in accordance with an embodiment of the present patent application;

[0042] FIG. 11 shows a shaping / forming die system with the piercing / punch system in accordance with an embodiment of the present patent application; and

[0043] FIG. 12 shows a shaping / forming die system with both the trim system and the piercing / punch system in accordance with an embodiment of the present patent application.DETAILED DESCRIPTION

[0044] The present disclosure pertains to methods and systems for hot stamping steel sheets (also referred to as blanks) to form parts with tailored tempered properties. The steel sheet or blank has a high emissivity coating provided thereon. However, portions of the coating is removed prior to the blank being heated to a predetermined temperature, and then press-formed in a stamping press (which may also have heating components in some embodiments to reduce cooling speeds of certain portions of the blank), and then quenched to be hardened. The quenching may optionally take place in the stamping press, or in a separate operation.

[0045] The heating is such that the steel reaches a temperature range at which its metal structure becomes austenite single phase in the regions having the high emissivity coated (HEC), but does not reach austenitic temperatures in the regions that have had the HEC removed.

[0046] In one embodiment, the high emissivity coating is on both sides of the blank (e.g., both sides of the blank in coil configuration). In another embodiment the HEC is only on one side of the blank.

[0047] As noted above, before the blank is placed in a furnace, the coating is removed from certain portions of the blank so that coating would only be on the areas where it is desired for the transformation to Austenite in the furnace and subsequent martensitic phase during quench. For the embodiment where the coating is removed from opposite sides of the blank, the regions of removal on the opposite sides where the removal takes place will be aligned with one another (i.e., aligned with respect to one another on opposing sides of the blank. In one embodiment, the alignment is achieved through CNC machining that deploys a friction or rubbing of the area to be removed on each side, in discreet locations programmed into the CNC machine controls. The locations to be removed can be aligned based upon the known distances from the regions to be removed from the edges of the blank on each side of the blank. Sufficient force is applied to remove only the HEC, without removing any underlying aluminum or aluminum alloy coating (such as AlSi, or any other coating). In another embodiment, robotics or motors are used to control movement of a laser beam that is used to ablate or burn off only the discreetregions of the HEC material on aligned opposite sides of the blank, without removing any of the underlying coating, by applying a specific beam with tuned energy / radiation that will remove only the HEC. In another embodiment, CNC machines can be used in a grinding, machining operation. In one embodiment, the force applied by the grinding, sanding or machining is sufficient to remove the HEC, yet prevent complete removal of any underlying aluminum or aluminum alloy coating.

[0048] In accordance with various embodiments of the present disclosure, the lower emissivity regions of a blank will heat up slower than the higher emissivity regions while in the furnace. This results in incomplete or zero transformation to austenite in the lower emissivity regions (e.g., remaining ferrite), and hence, these regions would not form martensite during quenching.

[0049] In some embodiments, the steel blank also has a layer or coating of aluminum or aluminum alloys (such as AlSi), and the HEC is a topcoat on top of the AlSi coating. As used herein, the term “coating” or “coated” can also be understood to mean “layer”.

[0050] In one embodiment, the AlSi can be 150gr. In another embodiment, the AlSi can be 80 gr. In one embodiment, the HEC is removed from portions of the blank without removing the underlying AlSi coating. However, in some embodiments, some amount of AlSi may be removed when removing the HEC. In embodiments in which the steel blank has an AlSi topcoat, the AlSi will protect the blank against oxidation during the forming process.

[0051] In another embodiment the HEC is applied to zinc-based coatings on the steel blank and used in the same fashion as described above and below with respect to AlSi coatings, with similar results.

[0052] The regions of the blank that have the HEC remaining thereon will have less reflectance than the portions that have had the material removed. This is because the HEC is generally a dark color (e.g., black, dark brown, dark grey), causing greater heat absorption in that region when placed in the furnace.

[0053] In some embodiments, as illustrated in FIG. 7A, the HEC layer 106 is provided directly on the steel substrate blank 102. Portions of the HEC layer 106 are removed from the steel substrate blank 102 as shown in FIG. 7B and described herein.

[0054] In other embodiments, as illustrated in FIGS. 8A, the steel substrate blank 102 is precoated on at least one side thereof with at least one layer of aluminum or aluminum alloy 104, and the HEC layer 106 is coated on top of that aluminum or aluminum alloy precoating. FIG. 8B shows portions of the HEC layer 106 that are removed from the aluminum or aluminumalloy precoating 104 on the steel substrate blank 102. In one embodiment, the HEC layer is a polymer layer having a thickness between 5 and 25 micrometers (pm). In one embodiment, the polymer may contain carbon pigments. In another embodiment, the polymerized layer comprises an acrylic type resin or an epoxy. In one embodiment, the HEC comprises activated carbon in a polymerized layer. In some embodiments, the steel substrate blank can be coated with any of the methods, layers, and materials as described in U.S. Patent No. 10,619,224 (“US Patent ‘224”), hereby incorporated by reference in its entirety.

[0055] In one embodiment, the HEC remaining on the blank will fully combust within the furnace process, as the furnace temperature would be sufficiently high to combust the chosen HEC material.

[0056] To perform the hot stamping, the steel can be heated in a standard furnace, thus not requiring any specially engineered heating tool. In one embodiment, a conventional hot stamp furnace can be used (e.g., a chamber style or roller hearth furnace).

[0057] In one embodiment, the high emissivity coating is applied in the coil or blank state on one or both sides of the blank. This coating would be applied only to the areas where it is desired for the transformation to Austenite in the furnace and subsequent martensitic phase during quench.

[0058] In another embodiment, the coating is applied to the entire blank (on one or both side), and then subsequently removed from the regions in which it is desired to have little or no martensite formed.

[0059] In one embodiment, the steel blank is a standard 22MnB5 blank.

[0060] FIG. 1 shows a graph having heating curves of the HEC having a 1.5 millimeter (mm) thickness (referred to as heating curve / profile “A” in FIG. 1), and the HEC having a 2.0 mm thickness (referred to as heating curve / profile “B” in FIG. 1) in accordance with an embodiment of the present patent application. FIG. 1 also shows a heating curve of a comparable gauge blank (e.g., standard 22MnB5 blank having 1.5 mm thickness) without the HEC thereon. The comparable gauge blank without the HEC thereon may be referred to as heating curve / profile “C” in FIG. 1. The left hand side Y-axis in FIG. 1 shows temperature measured in degrees centigrade (°C) and the X-axis shows time measured in seconds. For example, the HEC having a 1.5 mm thickness may also be referred to as HEC1.5, the HEC having a 2.0 mm thickness may also be referred to as HEC2.0, and the blank having no HEC may also be referred to as HECNO.

[0061] At approximately 97 seconds (s), HEC1.5 reaches 930 °C at which there may be 100 % formation of Austenite and HEC2.0 reaches 860 °C at which there may be 100 % formationof Austenite. Also, at approximately 108s, HECi 5 reaches 950 °C at which there may be 100 % formation of Austenite and HEC2.0 reaches 900 °C at which there may be 100 % formation of Austenite. Further, at approximately 130s, HEC1.5 is still at 950 °C at which there may be 100 % formation of Austenite and HEC2.0 reaches 940 °C at which there may be 100 % formation of Austenite.

[0062] At approximately 97s, HECNO reaches 730 °C at which there may be 0 % formation of Austenite. At approximately 108s, HECNO reaches 760 °C at which there may be 0 % formation of Austenite. At approximately 130s, HECNO is still at 820 °C at which there may be 80 % formation of Austenite.

[0063] Heating profiles / curves in FIG. 1 demonstrate the effectiveness of the coating where the high emissivity coated portions of the blank can reach above the final austenitic phase transformation temperature (interchangeably referred to as AC3) temperature in approximately 97s and the comparable gauge blank without the HEC is still at temperature of 730 °C, which is well below the Ac3 temperature, and just at beginning of the transformation of austenite (interchangeably referred to as AC 1) temperature, which results in a very small volume fraction of austenite resulting in minimal to no transformation to martensite after quench. At the very least, it can be said that less martensite is formed after quench in regions of the blank where the HEC was removed. It should be noted, that as used herein, the term non-martensitic is not limited to arrangements that have absolutely zero martensite, as a person of ordinary skill in the art would understand that some martensite may be formed in regions intended to be non- martensitic. Thus, the term non-martensitic can be understood to be substantially or predominantly non-martensitic, as would be understood by a person of ordinary skill in the art.

[0064] FIG. 2 illustrates an embodiment of the present disclosure wherein a vehicle pillar (e.g., a B-Pillar) has been formed. The area in grey shading has undergone martensitic phase transformation. It had the HEC layer thereon prior to being placed in the furnace. The area in white (shown in rectangular box) is a soft-zone of the B-Pillar. It had the HEC removed therefrom, and is thus standard press hardened steel material in that region (with or without AlSi coating). For example, in one embodiment, the B-Pillar can be of the type disclosed in International Patent Application No. PCT / US2017 / 024200, filed, March 26, 2017, (claims priority to U.S. Provisional Patent Serial No. 62 / 314,764, filed March 29, 2016), both are hereby incorporated by reference in their entirety. In another embodiment, the grey shaded area has a layer of Al Si thereon, has as well as the HEC on top of the Al Si, prior to entering the furnace.

[0065] The method of removal of the HEC can be with laser or by the chemical removal methods disclosed herein or other methods.

[0066] FIG. 3 is another representation of a vehicle member (e.g., a pillar member) in another embodiment. In this embodiment, the area in grey shading is martensitic and have the HEC remaining thereon prior to entering into the furnace, while the area in white are formed as vehicle pillar flanges that are softer and not martensitic (the HEC was removed prior to entering the furnace). These flange regions of the pillar are configured to be connected with other structures in the vehicle. For example, they may be pierced, etc., as disclosed in U.S. Patent No. 10,457,997, hereby incorporated by reference in its entirety. The method of removal of the HEC can be with laser or with chemical removal methods.

[0067] In another embodiment, shown in FIG. 4, is a vehicle floorpan. The “hard” area had the HEC remaining thereon prior to being placed in the furnace and is martensitic (i.e., relatively harder region of the floorpan). The “soft” area had the HEC removed therefrom prior to entering the furnace and is a relatively softer region of the floorpan. The transition region is between the martensite and soft region. In one embodiment, the soft zone has a hardness between approximately 140 Vickers Pyramid Number (HV) and approximately 270 HV. In one embodiment, the hard zone has a hardness between approximately 400 HV and approximately 2000 HV. In one embodiment, the transition region has a hardness between approximately 270 HV and approximately 400 HV.

[0068] The process and systems aren’t limited to the parts above. For example, for structural parts, it is contemplated that the following components can be formed: A-Pillar, A-Pillar reinforcement, Side member, B-Pillar, B-Pillar reinforcement, Hinge Pillar, Roof rail, Header, Roof bow, Door Ring, Double Door Ring, Front rail, Rear rail, Side reinforcement, Rocker rail, Rocker panel, Fire wall upper, Fire wall lower, Fire wall reinforcement, tunnel, and tunnel reinforcement can be formed in non-limiting examples. For BEV and EV specific components, it is contemplated that a side member of Battery tray, cross member of battery tray, reinforcement members of a battery tray, corner reinforcement of a battery tray, battery tray cover, and or battery tray cover reinforcements can be made in non-limiting examples.

[0069] More generally speaking, in one embodiment, the strength of the soft zone can be adjusted based on the percent formation of austenite controlled via heating. In one embodiment, the portions with the HEC removed will be heated to between 500 °C and 700 °C, while the portion with HEC remaining will be heated to between 880 °C and 975 °C.

[0070] With respect to one embodiment, in terms of quenching equal cooling may be applied in all areas post-heating. This can be done, for example, by water quenching to all areas. In another embodiment, the area of higher temperature on the blank due to HEC remaining thereon during heating may have enhanced cooling relative to the lower temperature regions.

[0071] In one embodiment, quenching is done by hot stamp die cooling, which utilizes water cooling channels in the die, to remove thermal energy with each stroke. Quenching in this manner can achieve cooling at a rate of greater than 20 °C per second.

[0072] This process herein prevents spring back of the formed metal part and provides the manufacture of the tailor tempered formed product high with high dimensional accuracy and desired regional strength.

[0073] In various embodiments, the areas of greater hardness where the HEC remained during heating can be in the tensile strength range of between 1000 to 2000 Mega pascal (MPa). In various embodiments, by contrast, where the HEC has been removed, the tensile strength of steel may be in the range of 450 MPa to 900 MPa, and a yield strength of between 300 MPa to 700 MPa., and in another embodiment between 340 MPa to 600 MPa. In one embodiment, a difference in Vickers hardness between the portion where the HEC has been removed vs. where the HEC remains is at least 100 HV, and in one embodiment between 100 HV to 500 HV, while in another embodiment it is between 100 HV to 350 HV. The hard zones are achieved above through phase transformation.

[0074] FIGS. 5 and 6 disclose some of the physical attributes and properties of “AlSi” regions and “HEC” regions. FIG. 5 shows the results and various experiments conducted on a standard 22MnB5 blank that has an AlSi coating. The rows labeled with “HEC” indicate that the HEC was not removed therefrom, whereas the rows labeled “AlSi” indicate regions where the HEC has been removed. All blanks were heated in a hot stamp furnace with the indicated residence time to determine the resultant mechanical properties. It can be clearly shown that samples with HEC was able to meet typical required “hardzone” properties with a tensile strength greater than 1300 MPa and a yield strength greater than 950 MPa. Al-Si samples heated under the same conditions were able to meet “softzones” properties with a tensile strength greater than 460 MPa and a yield strength greater than 340 MPa.

[0075] In the FIG. 6 below, shows the results and various experiments conducted on a standard 22MnB5 blank that has an AlSi coating. These measurements are just examples of obtainable properties samples 1, 2, 3 has the HEC whereas samples 4 and 5 had the HEC removed. It can be clearly demonstrated that samples with the HEC was able to reach typical“hard” properties which are above 400 HV whereas the samples with the HEC removed was able to reach typical “soft” properties below 190 HV.

[0076] In terms of the Al Si coating, the thickness thereof after stamping may, in one embodiment, be in the range of between 15 pm and 50 pm. A diffusion layer between the AlSi layer and base steel material may also be included with a thickness of between 1 pm and 16pm.

[0077] As described above, in some embodiments, such as shown in FIG. 7 below, the HEC 106 is applied directly to the substrate 102, and the HEC 106 is removed from the desired locations, while in other embodiments, the AlSi (or other) material layer 104 is disposed on the substrate, and the HEC layer is disposed on the layer 104 (prior to any removal thereof). In one embodiment, as illustrated in FIG. 8, the HEC 106 is completely removed without removing any of the aluminum based (e.g., AlSi) material 104 underlying the coating. This is achieved, for example, by frictionally rubbing ethanol on the HEC. A laser (e.g., a CO2 laser or the like) or CNC machine as previously described may be used to remove the HEC. Areas that should have the HEC kept thereon can optionally be masked from being exposed or subjected to ethanol, although that is not necessary.

[0078] In another embodiment, the HEC is completely removed without removing any of the AlSi material by application of laser ablation techniques, where the energy level is set sufficiently high to remove HEC without removing AlSi 104.

[0079] In yet other embodiments, partial removal of AlSi 104 may optionally take place upon removal of the HEC. This may be done in order to ensure complete removal of the HEC 106.

[0080] In another embodiment, a small amount of HEC material 106 (e.g., a very thin layer) can remain and still achieve the softer material properties, as the HEC material has been largely removed and no longer performs the full intended function.

[0081] In one embodiment, the HEC 106 used herein may be a dark paint. In another embodiment the HEC used herein may be of the type of material described in the U.S. Patent ‘224. The HEC material 106 may be applied by dipping the steel blank into the HEC material while the HEC is in a liquid form so that it is formed on both sides of the steel, or by spraying the HEC material onto one or both sides of the steel blank. In one embodiment, the spraying operation may cover the entirety of one side, or both sides, of the blank.

[0082] The steel blank to be hot-stamped can be hot-rolled steel sheets, cold-rolled steel sheets, or plated steel sheets, for example. The plated steel sheets, in one embodiment, have been galvanized (e.g., hot-dip galvanized). In another embodiment, aside from the aforementioned possibility of AlSi coating, the steel blank may instead by subject to platingwith aluminum, a zinc alloy containing aluminum, Mg, Si, Cr, or Ni, for example, and although Al Si may be used as described herein in accordance with some embodiments, it should be understood that any of these other materials may also be used and are contemplated as being equally part of this disclosure.

[0083] In terms of the quenching process, in one embodiment this may take place as a simple stand-alone quenching operation (outside a die). In another embodiment, the quenching is achieved inside the hot stamping die.

[0084] In one embodiment, when quenching by hot stamping is performed after heating of the blank to a temperature between approximately 800 °C and approximately 900 °C. (so that the HEC coated portions transform to the austenite single phase), the strength of that region with the coating remaining may reach 1350 MPa to 2000 MPa. In one embodiment, it may reach between approximately 1500 MPa and approximately 1600 MPa. For regions that are heated to approximately 730 °C or less, so that transformation into the austenite signal phase is not complete, in one embodiment the steel blank may not increase in strength above its original level.

[0085] In one embodiment, the blanks are processed such that the portion having the HEC thereon reaches above the AC3 temperature. A short dwell time may be desired to ensure the portion of the blank without HEC does not continue to gain excessive heat so that region does not reach above the AC3 temperature.

[0086] In one embodiment, the portion without the HEC can be heated to any temperature less than the AC3 temperature, which would result in a phase fraction of ferrite and austenite dependent on blank temperature.

[0087] If the area without the HEC is below the AC1 temperature, a fully ferritic microstructure can be achieved.

[0088] In one embodiment, the tensile strength in the HEC region is greater than 1300 MPa, and yield strength in HEC region is greater than 950 MPa.

[0089] In another embodiment, areas without HEC would be a mixed phase after stamping (Ferrite / Bainite / Martensite) if heated above the AC1 temperature and less than the AC3 temperature. In one embodiment, areas without HEC heated below the AC1 temperature would be ferritic.

[0090] Generally speaking, for trimming and piercing parts that have been hot stamped, it is desirable and easier to trim portions off the edges of the part, or punch holes in the part, inportions of the part that are softer rather than harder. Specifically, for example, it is desirable to punch areas that have not achieved martensitic hardness levels.

[0091] In one embodiment herein, when the cooling die closes to quench the part, some areas will ultimately achieve martensite and some areas will not. As a result, in the present disclosure, there is no time restriction within which to pierce and trim such areas that do not have martensite. This is opposed to an arrangement in which the entire part will ultimately reach martensite, in which case it might be desirable to trim and pierce the parts when they are still hot (e.g., 500 °C or 600 °C) and have not achieved martensite (such trim and / or pierce operation would need to occur within a tight time window).

[0092] In one embodiment, the trimming and / or piercing will take place in the die, on nonmartensite portions within 2 seconds or less after the part is quenched. However, it should be appreciated that the trimming and / or piercing can be done at times much later than that. In fact, in another embodiment, the trimming and / or piercing of the softer regions can be done after the part is removed from the cooling dies in a separate process, specifically for example, in a separate tool outside of the cooling die.

[0093] In one embodiment, the trimming and / or piercing can be conducted as the part commences the cooling / quenching process, and is conducted in parallel with (at the same time as) quenching. In another embodiment, the trimming and / or piercing is conducted after quenching is complete.

[0094] Referring to FIG. 9, the shaping die system 5000 may include an upper shaping die portion 5002, a lower shaping die portion 5004, and a plurality of cooling channels 5006, 5012. The upper die portion 5002 and the lower die portion 5004 may be made of steel material. The upper die portion 5002 and the lower die portion 5004 may be formed of a heat conducting material such as tool steel material.

[0095] Each die member / portion 5002, 5004 may include a forming or die surface 5008, 5010 and a plurality of cooling channels 5006, 5012. The die surface 5008, 5010 may include portion of the exterior surface of a die 5002, 5004 that forms a hot formed component. The die surface 5008, 5010 may include a die surface 5008, 5010 that has a three-dimensionally contoured shape that is not conducive for reliably facilitating an austenite-to-martensite phase transformation in volume production if the die surface 5008, 5010 were to be cooled via the cooling channels 5006, 5012 that are formed by gun drilling the cooling channels 5006, 5012 through one or two sides of the dies 5002, 5004. Each cooling channel 5002, 5004 may be offset from the respective die surface 5008, 5010 by a predetermined distance and this distancecan be consistent along the length of the cooling channel 5006, 5012. The die surfaces 5008, 5010 may cooperate to form a die cavity 5014 therebetween.

[0096] A blank, which can be formed of an appropriate heat-treatable steel can be pre-heated to a predetermined temperature, and can be placed in the die cavity between the die surfaces. The lower and upper dies can be brought together (i.e., closed) in a die action direction via a conventional stamping press to deform the blank so as to form and optionally trim / punch a hot-stamped component. Cooling fluid, such as water, gas or other fluid medium, which can be provided by a cooling system (e.g., a cooling system that conventionally includes a reservoir / chiller and a fluid pump) can be continuously circulated through the cooling channels 5006, 5012 to cool the lower and upper dies, respectively. It will be appreciated that the circulating cooling fluids will cool the lower and upper dies and that the lower and upper dies will quench and cool the hot-stamped component. The stamping press can maintain the lower and upper dies in a closed relationship for a predetermined amount of time to permit the hot-stamped component to be cooled to a desired temperature.

[0097] Also, referring to FIG. 9, the trim (or trimming) system 2000 may include an upper trim portion 2002, a lower pad 2004, and the lower form / shaping block 5004 with a trim edge 2008. The upper trim portion 2002 and the lower trim portion may be made of steel material.

[0098] In one embodiment, the upper trim portion 2002 and the lower pad 2004 with the edges of the blank / hot formed component therebetween may be configured to be movable downwardly along the longitudinal axis L-L and with respect to the stationarily positioned / disposed lower form block 5004 with the trim edge 2008 (and the stationarily positioned / disposed upper die portion 5002). This movement of the upper trim portion 2002 and the lower pad 2004 may facilitate the shearing / trimming of the edges of the hot formed component. The trim system 2000 may be part of the die or the shaping / cooling die 5000. The trim system 2000 may be part of a separate tool outside of the cooling die. In one embodiment, the pad does not perform the trimming. The lower form block 5004 has the trim steel edge and the upper block 2002 also has a trim steel edge. These male / female edges create the cut trim edge on the part.

[0099] The trim system 2000 may be a hydraulic trim system 2000. The trim system 2000 may be powered by a hydraulic cylinder (drive system). That is, the hydraulic cylinder may be configured to move the upper trim portion 2002 along a longitudinal axis L-L (and towards the lower pad 2004, and the lower form block 5004 with the trim edge 2008) and then move the upper trim portion 2002 and the lower pad 2004 together downwardly (with the edges of theblank / hot stamped component therebetween) to perform the trimming operation. In other embodiments, the drive system may be pneumatic system, pneumo-hydraulic system, electromechanical system, etc.

[0100] Although the trim system 2000 is shown in FIG. 9, the details of the trim system 2000 are not shown in the present patent application, the trim system may have the similar configuration and operation as the pierce punch system 1000 of FIG. 10 except that the trim system 2000 may be configured to perform the trimming operations / functions rather than piercing / punching operations / functions of the punch system 1000. As would be appreciated by a person skilled in the art, the trimming operation may include removal of excess steel / metal from the formed part to allow the formed part to reach the finished / final stage / form and / or to prepare the formed part for subsequent operations.

[0101] FIG. 10 shows a punch system or a pierce punch system 1000. The piercing system 1000 may be configured to punch / pierce (single or multiple) holes, slots, notches, custom shaped openings, etc. through desired locations of the formed part.

[0102] The piercing system 1000 may include a pierce punch / punch 1002, a drive system 1004 configured to drive the punch 1002, a punch extension 1006 configured to be connected between the drive system 1004 and the punch 1002, and a sensor 1008.

[0103] FIG. 10 shows the piercing system 1000 with just the lower die portion 5004 (with the respective cooling channels 5012). FIG. 11 shows the piercing system 1000 with both the upper die portion 5002 and the lower die portion 5004 (and their respectively cooling channels 5006, 5012). The piercing system 1000 is disposed in the upper die portion 5002 as shown in FIG. 11. FIG. 12 show the upper die portion 5002 and the lower die portion 5004 (and their respective cooling channels 5006, 5012) along with the piercing system 1000 and the trimming system 2000.

[0104] The piercing system 1000 may be a hydraulic piercing system 1000. The piercing system 1000 may be powered by a hydraulic cylinder (drive system) 1004. That is, the hydraulic cylinder 1004 may be configured to move the punch 1002 along a longitudinal axis L-L to perform the piercing operation. That is, the hydraulic cylinder 1004 may be configured to drive the punch 1002 between a retracted configuration and an extended configuration along the longitudinal axis L-L. In other embodiments, the drive system 1004 may be pneumatic

[0105] The piercing system 1000 may be part of the die or the cooling die. The piercing system 1000 may be part of a separate tool outside of the cooling die.

[0106] In the embodiments of FIGS. 9 and 10, it should be appreciated that the HEC can be initially provided across the entire blank and then removed as discussed above. However, for these embodiments, it should also be appreciated that HEC can be initially applied only in the regions that are intended to have more martensite formed thereon, and need not have HEC removed.

[0107] In another embodiment, different degrees or amounts (or densities) of coating are provided over different areas of the blank. For example, in some areas the HEC can be dispersed in some regions, and more continuous in others. In this embodiment, the (more) denser HECs will reach higher temperatures, more quickly.

[0108] In one embodiment, different areas of the blank can be coated with different types of HEC, which each type being configured to allow the blank to be heated at different rates in the die. For example, in one embodiment, the different HEC provides for different thermal emissivity. For example, each HEC can be of different colors each color having a different reflectivity or different emissivity than others. These colors may include white, grey, black, or other colored coatings. In one embodiment, the heat profile of each region of the blank can be controlled based not only on the temperature of the furnace, or different temperature regions of the furnace, but also based on the localized HEC coating thereon.

[0109] The present patent application and its various embodiments as described above uniquely address the observed, noted and researched findings and improve on the prior and current state of the art systems. The listed products, features and embodiments as described in the present patent application should not be considered as limiting in any way.

[0110] Although the present patent application has been described in detail for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that the present patent application is not limited to the disclosed embodiments, but, on the contrary, is intended to cover modifications and equivalent arrangements that are within the spirit and scope of the appended claims. In addition, it is to be understood that the present patent application contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.[OHl] The illustration of the embodiments of the present patent application should not be taken as restrictive in any way since a myriad of configurations and methods utilizing the present patent application can be realized from what has been disclosed or revealed in the present patent application. The systems, features and embodiments described in the present patent application should not be considered as limiting in any way. The illustrations arerepresentative of possible construction and mechanical embodiments and methods to obtain the desired features. The location and / or the form of any minor design detail or the material specified in the present patent application can be changed and doing so will not be considered new material since the present patent application covers those executions in the broadest form.

[0112] The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed.

[0113] When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0114] Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.

[0115] Terms of degree such as “generally,” “substantially,” “approximately,” and “about” may be used herein when describing the relative positions, sizes, dimensions, or values of various elements, components, regions, layers and / or sections. These terms mean that such relative positions, sizes, dimensions, or values are within the defined range or comparison (e.g., equal or close to equal) with sufficient precision as would be understood by a person of ordinary skill in the art in the context of the various elements, components, regions, layers and / or sections being described. For example, when referring to a numerical value, the terms “generally,” “substantially,” “approximately,” and “about” may mean ±5% to ±10% of a recited value or such other percentage or value as would be understood to a person of ordinary skill in the art. In this way, the present patent application contemplates various advantageous configurations of and describes their performance in a way that allows a person of ordinary skill to ascertain the scope of protection of the claimed subject matter. However, it is also understood that such measurements, by their nature, are not always exactly reproducible and that some variation is to be expected. Thus, the above is intended to provide a reasonable range about various measured quantities without rendering the present disclosure to be unclear or indefinite. Furthermore, measurements of manufactured devices may vary due to some variations in the physical device dimensions themselves. In this way, the terms “generally,” “substantially,” “approximately,” and “about” may also apply to physical dimensions, when appropriate and as understood by a person of ordinary skill in the art.

[0116] The foregoing illustrated embodiments have been provided to illustrate the structural and functional principles of the present patent application and are not intended to be limiting. To the contrary, the present patent application is intended to encompass all modifications, alterations and substitutions within the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A method for forming a part that has tailored tempered properties, comprising: receiving a blank of steel material having a high emissivity coating on at least one side thereof; removing a portion of the high emissivity coating (HEC) from portions of the blank; heating the blank in a furnace, wherein the regions of the blank having the HEC thereof remaining thereon are heated more quickly in the furnace than the portions where the HEC has been removed; and quenching the blank after said heating such that martensite is formed in regions of the blank at which the HEC was not removed, wherein less martensite is formed in regions of the blank at which HEC was removed.

2. The method according to any of the above claims, wherein a coating of AlSi is disposed on the blank of steel material underlies the HEC, and wherein the removing removes only the HEC without removing the Al Si coating.

3. The method according to claims 1 or 2, wherein the removing is performed by laser ablation of the HEC.

4. The method according to claims 1 or 2, wherein the removing is performed by chemical treatment.

5. The method according to claims 1 or 2, wherein the removing is performed by etching with an acid material.

6. The method according to claims 1 or 2, wherein the removing is performed by rubbing ethanol on the HEC.

7. The method according to any of the above claims, wherein the HEC is disposed on opposite sides of the blank of steel material.

8. The method of claim 2, wherein a portion of the AlSi is removed as a result of the removal of the HEC.

9. The method of claim 2, wherein none of the AlSi is removed as a result of the removal of the HEC.

10. The method of claims 1 or 2, wherein the removing is performed by a mechanical grinding operation.

11. The method of claims 1 or 2, wherein the removing is performed by a mechanical sanding operation.

12. A method for forming a pillar member for a vehicle, comprising: receiving a blank of steel material having a high emissivity coating on at least one side thereof; removing a portion of the high emissivity coating (HEC) from portions of the blank that are to be formed into a lower, larger dimensioned portion of the B-pillar in relation to at least one upper portion of the B-pillar; heating the blank in a furnace, wherein the regions of the blank having the HEC thereof are heated more quickly than the portions where the HEC has been removed; quenching the blank after said heating such that martensite is formed in regions of the blank at which the HEC was not removed, and wherein less martensite is formed in regions of the blank at which HEC was removed; and stamping and trimming the blank so as to provide the blank with a pillar configuration, wherein the lower, larger dimensioned portion is softer than said at least one upper portion of the B-pillar.

13. A method for forming a pillar member for a vehicle, comprising: receiving a blank of steel material having a high emissivity coating on at least one side thereof;removing a portion of the high emissivity coating (HEC) from portions of the blank that are to be formed into an edge portion of the B-pillar that is to be formed into a flange portion of the pillar member; heating the blank in a furnace, wherein the regions of the blank having the HEC thereof are heated more quickly than the portions where the HEC has been removed; quenching the blank after said heating such that martensite is formed in regions of the blank at which the HEC was not removed, and wherein less martensite is formed in regions of the blank at which HEC was removed; and stamping and trimming the blank so as to provide the blank with a pillar configuration having said flange portion, wherein the flange portion is softer than said at least one other portion of the B-pillar.

14. A method for forming a part that has tailored tempered properties, comprising: heating a blank of steel material in a furnace, the blank having a high emissivity coating (HEC) on some regions thereof and devoid of the HEC on other regions thereof; forming the blank and quenching the blank in a forming die, after said heating, such that martensite is formed in regions of the formed blank that had the HEC and regions of the formed blank that were devoid of the HEC are non-martensitic; and trimming and / or piercing the non-martensitic portions of the formed blank in the forming die.

15. The method of claim 14, wherein the formed blank includes a pillar member.

16. The method of claim 15, wherein the formed blank includes a B-pillar.

17. The method of claim 14, wherein the formed blank includes edges having the non- martensitic portions, and wherein, after the forming and the quenching procedures, the trimming is configured to trim the non-martensitic portions of the edges of the formed blank.

18. The method of claim 14, wherein, after the forming and the quenching procedures, the piercing is configured to punch holes in the non-martensitic portions of the formed blank.

19. The method of claim 14, wherein the non-martensitic portions of the formed blank are softer than the martensitic portions of the formed blank.

20. The method of claim 14, wherein, prior to the heating the blank, removing the HEC from portions of the blank to create the regions of the blank that are devoid of the HEC.

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