Method for forming a susceptor

Abstract

A method for forming a susceptor (10) for an induction heating assembly (14). The method includes providing a blank (40). The blank (40) comprises an austenitic stainless steel. The method further includes subjecting the blank to a plastic deformation step to form an α'-martensite phase in the austenitic stainless steel, which increases its magnetic permeability.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to methods of forming susceptors, and more particularly to methods of forming susceptors for induction heating assemblies. [Background technology]

[0002] In recent years, aerosol-generating devices (also known as vaporizers), which heat rather than burn or combust an aerosol-generating substrate to produce an aerosol for inhalation by the device user, have become popular with consumers as an alternative to the use of traditional tobacco products.

[0003] A variety of devices and systems are available that can provide heat to an aerosol-generating substrate using one of several different techniques. One such technique is to provide an induction heating assembly. Such an assembly uses an electromagnetic field generator, such as an induction coil, to couple with a susceptor heating element and generate an alternating electromagnetic field that inductively heats the susceptor heating element. Heat from the susceptor is transferred to the substrate, for example, by conduction, and the substrate heats, generating an aerosol for inhalation by a user of the device. Summary of the Invention [Problem to be solved by the invention]

[0004] In use, the susceptor is positioned in close proximity to or in contact with the aerosol-generating substrate and is therefore preferably formed of a material that is resistant to corrosion. In this regard, austenitic stainless steel is a suitable susceptor material due to its high resistance to corrosion. However, austenitic stainless steel susceptors do not have sufficient magnetic permeability to provide efficient heating within an induction heating assembly.

[0005] Therefore, there is a need to address this shortcoming. [Means for solving the problem]

[0006] According to a first aspect of the present disclosure, there is provided a method of forming a susceptor for an induction heating assembly, the method comprising: providing a blank comprising an austenitic stainless steel; and subjecting the blank to a plastic deformation step to form an α'-martensite phase in the austenitic stainless steel, which increases its magnetic permeability.

[0007] By subjecting the blank to a plastic deformation step, the fine grain structure of the austenitic stainless steel is transformed to include the α'-martensite phase, resulting in an increase in its permeability. This improves the heating efficiency and therefore performance of the susceptor in the induction heating assembly. The susceptor's resistance to corrosion remains high.

[0008] Optionally, the plastic deformation step includes deep drawing the blank to form a sidewall of the susceptor, the sidewall having an open first end and a base at a second end opposite the first end, the base closing the sidewall at the second end.

[0009] Deep drawing the blank may include forming a flange portion extending radially outward from the sidewall at the open first end, or the flange portion may be formed after deep drawing in a separate step.

[0010] Optionally, the method further includes cutting the sidewall to remove the base and open the second end.

[0011] The method may further include cutting the sidewall to remove the flange portion.

[0012] The sidewall may include one or more substantially flat sides. In other examples, the sidewall may be a cylindrical sidewall having a circular or elliptical cross-section. The method may further include selectively deforming the cylindrical sidewall. The cylindrical sidewall may be selectively deformed to provide one or more substantially flat portions or one or more substantially flat sides. The cylindrical sidewall may be selectively deformed by hydroforming or mechanical pressing.

[0013] The method may further include selectively deforming the sidewall by recessing an outer surface of the sidewall to form one or more inwardly directed protrusions on an inner surface of the sidewall.

[0014] In use, the inwardly directed protrusions extend into the heating compartment, compressing the aerosol-generating substrate. Compressing the aerosol-generating substrate allows for more efficient transfer of heat to the aerosol-generating substrate, maximizing energy efficiency while achieving more rapid heating. Compressing the aerosol-generating substrate improves heat conduction through the aerosol-generating substrate, for example, by eliminating voids.

[0015] The method may further include annealing the sidewalls and selectively deforming a portion of the sidewalls after annealing.

[0016] The permeability of the susceptor is selectively increased at locations corresponding to the portions of the sidewalls after annealing that are selectively deformed.

[0017] The sidewalls can have an inner diameter of 5 mm to 9 mm. Susceptors with sidewalls having these inner diameter dimensions optimize the balance between the amount of steam generated and the time (and therefore energy) required to generate the steam, thus further improving performance.

[0018] The sidewalls may have a thickness of 200 μm or less. The sidewalls may have a thickness of 90 μm to 110 μm. Susceptors having sidewalls with these thickness dimensions may be particularly suitable for being inductively heated during use.

[0019] The sidewalls can have an axial length between 0.5 mm and 20 mm. Susceptors with these axial length dimensions optimize the balance between the amount of steam generated and the time (and therefore energy) required to generate the steam, thus further improving performance.

[0020] The austenitic stainless steel may be AISI 304 or AISI 321.

[0021] The blank may be disc-shaped.

[0022] According to a second aspect of the present disclosure, there is provided a susceptor for an induction heating assembly, the susceptor being formed of an austenitic stainless steel containing an α'-martensite phase, the susceptor being formed by the method described in any of the preceding paragraphs.

[0023] According to a third aspect of the present disclosure, there is provided an aerosol generating device including an induction heating assembly, the induction heating assembly including a susceptor, the susceptor being formed of austenitic stainless steel containing an α'-martensite phase, the susceptor being formed by the method described in any of the preceding paragraphs.

[0024] According to a fourth aspect of the present disclosure, there is provided an induction heating assembly including a susceptor, the susceptor being formed of an austenitic stainless steel including an α'-martensite phase, the susceptor being formed by the method described in any of the preceding paragraphs.

[0025] According to a fifth aspect of the present disclosure, there is provided an aerosol-generating system comprising an aerosol-generating device and an aerosol-generating substrate, the aerosol-generating device comprising an induction heating assembly, the induction heating assembly comprising a susceptor, the susceptor being formed from austenitic stainless steel comprising an α'-martensite phase, the susceptor being formed by the method described in any of the preceding paragraphs.

[0026] Susceptors made of austenitic stainless steel with a fine-grained structure containing the α'-martensite phase have sufficient magnetic permeability to provide efficient heating within the induction heating assembly, improving performance. The susceptor's resistance to corrosion remains high. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 1 is a schematic diagram of an aerosol generation system. [Figure 2] FIG. 1 is a schematic perspective cutaway view of an induction heating assembly of an aerosol generating device. [Figure 3] FIG. 10 is a schematic perspective cutaway view of another induction heating assembly of another aerosol generating device. [Figure 4] A method of forming a susceptor for an induction heating assembly is shown. [Figure 5] 5 is a schematic perspective view of a blank for block A of the method of FIG. 4. FIG. [Figure 6] 5 is a schematic perspective view of the arrangement for block B of the method of FIG. 4. [Figure 7] FIG. 7 is a schematic bottom view of the arrangement of FIG. 6. [Figure 8] FIG. 5 is a schematic perspective view of the arrangement for block C of the method of FIG. 4. [Figure 9] FIG. 9 is a schematic bottom view of the arrangement of FIG. 8. [Figure 10] FIG. 5 is a schematic perspective view of the arrangement for block D of the method of FIG. 4. [Figure 11] FIG. 5 is a schematic perspective view of the arrangement for block H of the method of FIG. 4. [Figure 12] 5 is a schematic perspective view of another susceptor formed by the method of FIG. 4. [Figure 13] FIG. 13 is a schematic cross-sectional view of the arrangement of FIG. 12. DETAILED DESCRIPTION OF THE INVENTION

[0028] Embodiments of the present disclosure will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0029] Examples of the present disclosure provide methods of forming susceptor 10. Examples of the present disclosure also provide susceptor 10 that can be formed by, or is a product of, the described methods.

[0030] 1, a susceptor 10 according to an example of the present disclosure can be used as a heating element 12 as part of an induction heating assembly 14, i.e., an induction heating system. The induction heating assembly 14 is included in an aerosol-generating system 18. The aerosol-generating system 18 includes an aerosol-generating device 16 (also known as a vaporizer) and an aerosol-generating substrate 20. The aerosol-generating device 16 is a handheld, portable device, meaning that a user can hold and support the device 16 in one hand without assistance.

[0031] In some examples, the induction heating assembly 14 is included in the aerosol generating device 16 .

[0032] The susceptor 10 according to the examples of the present disclosure includes an electrically conductive material. In the examples of the present disclosure, the susceptor 10 includes austenitic stainless steel.

[0033] In use, the induction coil 22, i.e., electromagnetic field generator, included in the induction heating assembly 14 is arranged to be energized to generate an alternating electromagnetic field that couples with and inductively heats the susceptor 10 by eddy currents and magnetic hysteresis losses, resulting in electromagnetic-to-thermal energy conversion. Thus, the susceptor 10 according to examples of the present disclosure is inductively heatable. Heat from the susceptor 10 is transferred to the aerosol-generating substrate 20 by, for example, conduction, radiation, and convection, heating the aerosol-generating substrate 20 (without burning or combusting the aerosol-generating substrate 20), thereby generating vapor, which cools and condenses to form an aerosol for inhalation by a user of the aerosol-generating device 16.

[0034] Generally speaking, a vapor is a substance that is in the gas phase below its critical temperature, meaning that the vapor can be condensed into a liquid by increasing the pressure without decreasing the temperature. An aerosol, on the other hand, is a suspension of fine solid particles or liquid droplets in air or another gas. However, it should be noted that the terms "aerosol" and "vapor" can be used interchangeably herein, particularly with respect to the form of inhalable medium generated for inhalation by a user.

[0035] The induction coil 22 is energized by a power source 24 of the aerosol generating device 16, such as a battery. The aerosol generating device 10 typically includes a controller 26 and a user interface for controlling the operation of the aerosol generating device 16 via the controller 26.

[0036] The controller 26 is configured to detect the initiation of use of the aerosol generating device 16, for example, in response to a user input, such as pressing a button to activate the aerosol generating device 16, or in response to detected airflow through the aerosol generating device 16. As will be understood by those skilled in the art, airflow through the aerosol generating device 16 indicates an inhalation or "puff" by the user. The aerosol generating device 16 may include a puff detector, such as an airflow sensor (not shown), to detect airflow through the aerosol generating device 16.

[0037] The controller 26 includes electronic circuitry. The power supply 24 and electronic circuitry may be configured to operate at high frequencies. For example, the power supply 24 and electronic circuitry may be configured to operate at frequencies of approximately 80 kHz to 500 kHz, optionally approximately 150 kHz to 250 kHz, and optionally approximately 200 kHz. The power supply 24 and electronic circuitry could also be configured to operate at higher frequencies, such as in the MHz range, if desired.

[0038] The induction coil 22 may be disposed around the susceptor 10, for example, to surround or completely encircle the susceptor 10. The induction coil 22 may be substantially helical in shape. The induction coil 22 may be toroidal. The induction coil 22 may comprise Litz wire or Litz cable. However, it should be understood that other materials may be used. The induction coil 22 may be arranged to operate with a varying electromagnetic field having a magnetic flux density of about 20 mT to about 2.0 T (at its highest density point), in use.

[0039] 2 provides a cutaway view that schematically illustrates an induction heating assembly 14 of an aerosol generating device 16. The induction heating assembly 14 includes a susceptor 10 according to an example of the present disclosure.

[0040] 2, the induction heating assembly 14 is arranged such that the susceptor 10 surrounds the outer periphery of a heating compartment 28 configured to receive the aerosol-generating substrate 20. Alternatively, in another arrangement (not shown), the susceptor 10 may be arranged to protrude into the heating compartment 28 from an end 30 thereof and penetrate the aerosol-generating substrate 20 when the aerosol-generating substrate 20 is received therein. In such an example, the susceptor 10 may be a blade or a pin.

[0041] 2, induction coil 22 is positioned around susceptor 10 outside heating compartment 28 so as to surround susceptor 10. Induction coil 22 is helical in shape.

[0042] 2, the susceptor 10 is included in the aerosol-generating device 16. In other arrangements, the susceptor 10 may instead be provided within the aerosol-generating substrate 20 during manufacture.

[0043] 2 is an outer or peripheral susceptor, i.e., it can be positioned outside the aerosol-generating substrate 20. In other examples not shown, a susceptor 10 according to examples of the present disclosure can be a central or inner susceptor, i.e., it can be positioned within or inside the aerosol-generating substrate 20.

[0044] The susceptor 10 according to the example of the present disclosure has a sidewall 32. The susceptor 10 shown in Figure 2 is a susceptor tube 34 having a cylindrical sidewall 36 with a circular cross section. Thus, in the example of Figure 2, the susceptor 10 is cylindrical. The susceptor 10 of Figure 2 is open-ended, hollow, and elongated.

[0045] Figure 3 provides a cutaway view that schematically illustrates another induction heating assembly 14 of another aerosol generating device 16. The induction heating assembly 14 includes another susceptor 10 according to an example of the present disclosure. The induction heating assembly 14 is similar to the induction heating assembly 14 described above with reference to Figure 2, and corresponding components are identified using the same reference numerals. Only the differences relative to the arrangement of Figure 2 will be described here.

[0046] 3 is a susceptor tube 34 having a sidewall 32 that includes a plurality of flat portions 38. In other examples, a susceptor 10 according to examples of the present disclosure may include one or more substantially flat side surfaces 52, as shown, for example, in FIG.

[0047] Thus, in the examples of the present disclosure, the sidewall 32 of the susceptor 10 may be cylindrical with a circular or elliptical cross-section, or may include one or more substantially flat portions 38, or may include one or more substantially flat sides 52, i.e., flat sidewalls, or may include protrusions 50, i.e., modified portions, as described below. The susceptor 10 may be open-ended, hollow, and elongated.

[0048] Specific examples of susceptors 10 according to examples of the present disclosure include, but are not limited to, particulate susceptors, susceptor filaments, susceptor meshes, susceptor wicks, susceptor pins, susceptor rods, susceptor blades, susceptor strips, susceptor sleeves, susceptor tubes, and susceptor rings. The susceptor strips may be elongated.

[0049] Blocks AC of Figure 4 illustrate a method of forming a susceptor 10 for an induction heating assembly 14. Figures 5-9 illustrate generally the features and arrangements described with respect to Blocks AC of Figure 4.

[0050] With respect to block A, and referring to FIG. 5, the method includes providing a blank 40, the blank 40 comprising an austenitic stainless steel, and subjecting the blank to a plastic deformation step to form an α'-martensite phase in the austenitic stainless steel, which increases its magnetic permeability.

[0051] In some examples, the blank 40 is made from, and thus consists of, austenitic stainless steel, which is highly resistant to corrosion, a desirable characteristic for a susceptor material, particularly since, in use, the susceptor 10 is placed in close proximity to or in contact with the aerosol-generating substrate 20. The austenitic stainless steel may be AISI (American Iron and Steel Institute) 304 or AISI 321.

[0052] In the illustrated example, the blank 40 is planar. Thus, the blank 40 has a continuous flat or horizontal surface in all directions. In the illustrated example, the blank 40 is disk-shaped. The blank 40 may also be a sheet material.

[0053] 6 and 7, with respect to block B, optionally, the plastic deformation step includes deep drawing the blank 40 to form a sidewall 32 having an open first end 42 and a base 44 at a second end 46 opposite the first end 42. The base 44 closes the sidewall 32 at the second end 46. The base 44 completely closes the sidewall 32 at the second end 46. The base 44 is integral with the sidewall 32. Thus, the arrangement of FIGS. 6 and 7 is cup-shaped. The arrangement of FIGS. 6 and 7 has a cylindrical sidewall 36 with a circular cross-section.

[0054] Deep drawing of blank 40 includes forming a flange portion 48 that extends radially outward from sidewall 32 at open first end 42 .

[0055] 8 and 9, with respect to block C, optionally, the method further includes cutting the sidewall 32 to remove the base 44 and open the second end 46. Thus, the base 44, i.e., the closed end, is sheared off from the sidewall 32 after the deep drawing process. The arrangement of FIGS. 8 and 9 is a susceptor 10 in the form of a susceptor tube 34 having a cylindrical sidewall 36 with a circular cross-section. A flange portion 48 extends radially outward from the sidewall 32 at the open first end 42. The susceptor tube 34 of FIGS. 8 and 9 is open-ended, hollow, and elongated.

[0056] Without being bound by theory, subjecting the blank to a plastic deformation step changes the fine grain structure of the austenitic stainless steel to include an α'-martensite phase, increasing its permeability. This improves the heating efficiency and therefore performance of the susceptor 10 within the induction heating assembly 14. The susceptor's resistance to corrosion remains high.

[0057] The presence of the α'-martensite phase can be demonstrated by examining the microstructure of austenitic stainless steels with an optical microscope.

[0058] 6 and 7 on the base 44 provides some strengthening, and the flange portion 48 also provides some strengthening of its own. Thus, the flange portion 48 (i.e., collar) supports or holds the susceptor 10. However, the provision of both the base 44 and the flange portion 48 provides a greater degree of strengthening than either the base 44 or the flange portion 48 alone. This is primarily due to the fact that the flange portion 48 and the base 44 are located at opposite ends of the sidewall 32, i.e., neither end of the sidewall 32 is supported. Thus, the sidewall 32 is strengthened for better fracture resistance during further deformation after deep drawing, for example, to form a protrusion 50 or flatten at least a portion of the sidewall 32, as described below.

[0059] This is an effective method for forming the susceptor 10 and can be used, for example, to provide very thin sidewalls 32 in the ranges described below. In some examples, the deep drawing process involves pressing an austenitic stainless steel blank 40 with a punch tool (not shown) into a shaped mold (not shown). The austenitic stainless steel blank 40 is drawn radially into the mold by the mechanical action of the punch. Thus, the austenitic stainless steel blank is deformed. In some examples, a series of progressively smaller punch tools and dies can be used to form a tubular structure having a closed end 46 (i.e., base 44 at second end 46) and a susceptor tube 34 that is deeper than its end-to-end distance (hence the term "deep drawn"), a susceptor tube 34 that is relatively longer than it is wide. As a result, the sidewalls 32 of the susceptor tube 34 formed in this manner can be the same thickness as the original sheet metal blank 40. Likewise, the base 44 formed in this manner may be the same thickness as the initial sheet metal blank 40 .

[0060] The flange portion 48 may be formed at the first end 42 of the susceptor tube 34 by leaving a peripheral edge of the original sheet metal blank 40 (i.e., starting with more material in the blank 40 than is required to form the susceptor tube 34 and base 44) extending outward at the end of the sidewall 32 opposite the base 44. Alternatively, the flange portion 48 may be formed later in a separate step involving one or more of cutting, bending, rolling, swaging, etc.

[0061] In the example of FIGS. 6 to 9, the side wall 32 of the susceptor 10 is a cylindrical side wall 36 having a circular cross section.

[0062] Block D of Figure 4 illustrates an optional step in a method of forming a susceptor 10 according to an example of the present disclosure. Figure 10 illustrates a schematic diagram of the features described with respect to Block D.

[0063] 10 , with respect to Block D, in some examples, the method optionally further includes cutting sidewall 32 to remove flange portion 48. Thus, in such examples, the method includes trimming the ends of sidewall 32 (i.e., both ends 42, 46).

[0064] The arrangement of Figure 10 is a susceptor tube 34 having a cylindrical sidewall 36 with a circular cross section. The flange portion 48 has been removed. In the example of Figure 10, the susceptor tube 34 is cylindrical, open-ended, hollow, and elongated.

[0065] Block E of FIG. 4 illustrates another optional step in a method of forming a susceptor 10 according to an example of the present disclosure. With respect to Block E, in an example where the sidewall 32 of the deep-drawn susceptor 10 is cylindrical with a circular or elliptical cross-section (i.e., a cylindrical susceptor 10), the method may further include selectively deforming the cylindrical sidewall 36. The cylindrical sidewall 36 may be selectively deformed to provide one or more substantially flat sides 52 or one or more substantially flat portions 38, for example, as shown in FIG. 3 . An arrangement including two flat sides 52 is shown in FIGS. 12 and 13 . However, with respect to FIGS. 12 and 13 , the flat sides 52 are formed by a different mechanism, as described below. The cylindrical sidewall 36 may be selectively deformed by hydroforming or mechanical pressing. The cylindrical sidewall 36 may be selectively deformed before cutting the cylindrical sidewall 36 to remove the base 44 and / or flange portion 48.

[0066] Block F of FIG. 4 illustrates another optional step in a method of forming a susceptor 10 according to examples of the present disclosure. With reference to Block F, in some examples, the method optionally further includes selectively deforming the sidewall 32 to recess the outer surface of the sidewall 32 to form one or more inwardly directed protrusions 50 on the inner surface of the sidewall 32 (as shown in FIG. 11 , described below). The outer surface of the sidewall 32 may be recessed by hydroforming or mechanical pressing. The sidewall 32 may be selectively deformed before cutting the sidewall 32 to remove the base 44 and / or flange portion 48. The sidewall 32 may be a cylindrical sidewall 36 (i.e., a cylindrical susceptor 10) having a circular or elliptical cross-section, as shown in FIG. 11 , or may have a different shape.

[0067] In use, the inwardly facing protrusions 50 extend into the heating compartment 28, compressing the aerosol-generating substrate 20. Compressing the aerosol-generating substrate 20 allows for more efficient transfer of heat to the aerosol-generating substrate 20, maximizing energy efficiency while achieving more rapid heating. Compressing the aerosol-generating substrate 20 improves heat conduction through the aerosol-generating substrate 20, for example, by eliminating voids.

[0068] 4 illustrates an optional step in a method of forming a susceptor 10 according to examples of the present disclosure. With respect to Block G, in some examples, the method optionally further includes annealing the sidewalls 32.

[0069] Block H of Figure 4 illustrates an optional step in a method of forming a susceptor 10 according to an example of the present disclosure. With reference to Figure 11 with respect to Block H, the method optionally further includes selectively deforming a portion of the sidewall 32 after annealing.

[0070] 11 is a susceptor 10 in the form of a susceptor tube 34 having a post-annealed sidewall 32 that includes a plurality of protrusions 50, i.e., selectively deformed portions. In some examples, the protrusions 50 may include flat portions 38. The permeability of the susceptor 10 is selectively increased at locations of the post-annealed sidewall 32 that correspond to the protrusions 50.

[0071] The arrangement of Figures 12 and 13 shows a susceptor 10 in the form of a susceptor tube 34 having a sidewall 32 that includes two flat sides 52, i.e., flat sidewalls. In this example, the flat sides 52 are formed directly from the blank 40 by deep drawing. That is, the flat sides 52 are introduced by deep drawing based on the configuration of a punch tool and / or mold. The sidewall 32 of the susceptor tube 34 of Figures 12 and 13 has an axial length of 16 mm. Thus, the sidewall 32 of a susceptor 10 according to examples of the present disclosure may include one or more substantially flat sides 52.

[0072] In some examples, the sidewall 32 of the susceptor 10 according to examples of the present disclosure has an inside diameter, or inner diameter, of 5 mm to 9 mm. The sidewall 32 may preferably have an inner diameter of 5 mm to 8 mm, or 5.5 mm to 7.5 mm, or most preferably 7 mm. A susceptor 10 having a sidewall 32 with these inner diameter dimensions optimizes the balance between the amount of steam generated and the time (and therefore energy) required to generate the steam, thus further improving performance.

[0073] In some examples, the sidewall 32 of the susceptor 10 according to examples of the present disclosure has a thickness of 200 μm or less. Preferably, the sidewall 32 may have a thickness of 30 μm to 200 μm, or may have a thickness of 50 μm to 170 μm, or may have a thickness of 70 μm to 150 μm, or may have a thickness of most preferably 90 μm to 110 μm. The sidewall 32 may have a thickness of 100 μm. Susceptors 10 having sidewalls 32 with these thickness dimensions may be particularly suitable for being inductively heated during use.

[0074] In some examples, the sidewall 32 of a susceptor 10 according to examples of the present disclosure has an axial length of 0.5 mm to 20 mm. In some examples, the susceptor 10 can have an axial length of 3 mm to 5 mm, or an axial length of 4 mm. Susceptors 10 with these axial length dimensions optimize the balance between the amount of steam generated and the time (and therefore energy) required to generate the steam, thus further improving performance.

[0075] Examples of the present disclosure also provide a susceptor 10 for an induction heating assembly 14, the susceptor 10 being formed from an austenitic stainless steel containing an α'-martensite phase. The susceptor 10 may be formed by the methods described above.

[0076] Examples of the present disclosure also provide an induction heating assembly 14 that includes a susceptor 10 formed from an austenitic stainless steel containing an α'-martensite phase. The susceptor 10 may be formed by the methods described above.

[0077] Examples of the present disclosure also provide an aerosol generating device 16 that includes an induction heating assembly 14, which includes a susceptor 10 formed from an austenitic stainless steel containing an α'-martensite phase. The susceptor 10 may be formed by the methods described above.

[0078] Examples of the present disclosure also provide an aerosol-generating system including an aerosol-generating device 16 and an aerosol-generating substrate 20. The aerosol-generating device 16 includes an induction heating assembly 14, which includes a susceptor 10 formed of austenitic stainless steel containing an α'-martensite phase. The susceptor 10 can be formed by the method described above.

[0079] The susceptor 10, formed from an austenitic stainless steel with a fine-grained structure containing an α'-martensite phase, has sufficient magnetic permeability to provide efficient heating within the induction heating assembly 14. This improves performance. The susceptor 10 remains highly resistant to corrosion.

[0080] The drawings also illustrate a method of manufacturing an aerosol generating device 16 that includes an induction heating assembly 14, which includes a susceptor 10 formed from an austenitic stainless steel containing an α'-martensite phase. The susceptor 10 may be formed by the methods described above.

[0081] While exemplary embodiments have been described in the preceding paragraphs, it should be understood that various modifications may be made to those embodiments without departing from the scope of the appended claims. Thus, the breadth and scope of the claims should not be limited to the above-described exemplary embodiments.

[0082] Any combination of the above-described features in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

[0083] Unless the context clearly dictates otherwise, throughout this specification and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense, i.e., "including but not limited to", rather than in an exclusive or exhaustive sense.

Claims

1. A method of forming a susceptor (10) for an induction heating assembly (14), comprising: providing a blank (40), the blank (40) comprising austenitic stainless steel; subjecting said blank to a plastic deformation step to form an α'-martensite phase in said austenitic stainless steel, which increases its magnetic permeability; A method comprising:

2. The plastic deformation step deep drawing the blank (40) to form a sidewall (32) of the susceptor (10), the sidewall (32) having an open first end (42) and a base (44) at a second end (46) opposite the first end (42), the base (44) closing the sidewall (32) at the second end (46); Including, Deep drawing the blank (40) Preferably, the open first end (42) defines a flange portion (48) extending radially outward from the side wall (32). Including, The method of claim 1.

3. The method further includes cutting the sidewall (32) to remove the base (44) and open the second end (46), Optionally further comprising cutting said sidewall (32) to remove said flange portion (48). The method of claim 2.

4. the sidewall (32) includes one or more substantially flat sides (52); The method according to claim 2 or 3.

5. The side wall (32) is a cylindrical side wall (36) having a circular or elliptical cross section. The method according to claim 2 or 3.

6. further comprising selectively deforming the cylindrical sidewall (36). The method of claim 5.

7. the cylindrical side wall (36) being selectively deformed to provide one or more substantially flat portions (38) or one or more substantially flat sides (52); The method of claim 6.

8. the cylindrical side wall (36) is selectively deformed by hydroforming or mechanical pressing; 8. The method according to claim 6 or 7.

9. selectively deforming the sidewall (32) to recess the outer surface of the sidewall (32) thereby forming one or more inwardly directed protrusions on the inner surface of the sidewall (32). The method according to any one of claims 2 to 8.

10. annealing the sidewalls (32); Selectively deforming a portion of the annealed sidewall (32); Further comprising: The method according to any one of claims 2 to 9.

11. The side wall (32) has an inner diameter of 5 mm to 9 mm. The method according to any one of claims 2 to 10.

12. The sidewall (32) has a thickness of 200 μm or less. The method according to any one of claims 2 to 11.

13. The austenitic stainless steel is AISI 304 or AISI 321; The method according to any one of claims 1 to 12.

14. A susceptor (10) for an induction heating assembly (14), comprising: It is formed of austenitic stainless steel containing α'-martensite phase. Susceptor (10).

15. An aerosol generating device (16) comprising an induction heating assembly (14), The induction heating assembly (14) includes a susceptor (10); The susceptor (10) is formed of austenitic stainless steel containing an α'-martensite phase. An aerosol generating device (16).

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