Composite main body for a cutting tool

Abstract

The invention relates to a composite main body for a cutting tool (100), said composite main body comprising: a carrier main body (2) that is made of a steel with a carbon content of 0.2 to 0.65 percent by weight carbon; and a tool head main body (3) that is made of a precipitation-hardened maraging steel and is seamlessly and integrally bonded to the carrier main body (2), wherein the tool head main body (3), with respect to the carrier main body (2), has an HRC Rockwell hardness that is up to 11% greater or up to 11% smaller as measured by the standard Rockwell hardness scale HRC.

Description

[0001]Composite base body for a cutting tool The present invention relates to a composite base body for a cutting tool and a method for producing a composite base body for a cutting tool. EP 3815840 A1 shows a cutting tool in which the main body in the form of a cutting tool head is additively built onto an intermediate element. The main body and the intermediate element are made of a maraging steel. Maraging steels (“maraging”, from the English “martensite” and “aging”, i.e. martensite-hardenable steel) are a special group of martensitic steels with a high nickel content (i.e., usually more than 10 mass percent nickel) and a low carbon content (i.e.,Maraging steels (usually up to a maximum of 0.03 mass percent carbon) that can be manufactured in a comparatively ductile martensitic state and later strengthened by aging treatment. An aging treatment, or aging for short, is a process in which the hardness of a metal alloy containing a constituent in supersaturated solid solution increases over time as the constituent precipitates as a secondary phase containing the constituent, usually when the metal alloy is exposed to an elevated temperature. Maraging steels are characterized by high strength and hardness and are also typically well suited for additive manufacturing of components.The cutting tool known from EP 3815840 A1 typically warps so severely during heat treatment for precipitation hardening of the maraging steel that specified dimensions are no longer maintained, and strong mechanical stresses arise at the interface between the main body and the intermediate element. The object of the present invention is to provide a base body composite for a cutting tool that eliminates the disadvantages of the prior art and also enables a longer service life during cutting. The technical object of the present invention is achieved by the subject matter of claim 1. Advantageous developments of the invention can be found in the dependent claims, which can be freely combined with one another.The base body composite for a cutting tool comprises a carrier body made of a steel with a carbon content of 0.2 to 0.65 mass percent carbon, and a tool head body made of a precipitation-hardened maraging steel and seamlessly bonded to the carrier body, wherein the tool head body has an HRC Rockwell hardness that is up to 11% greater or up to 11% lower than the carrier body, measured according to the standard Rockwell hardness scale HRC. By making the carrier body from the steel, i.e. from a steel different from the maraging steel, and by having the tool head body have an HRC Rockwell hardness that is up to 11% greater or up to 11% lower than the carrier body, measured according to the standard Rockwell hardness scale HRC, distortion during precipitation hardening is surprisingly almost completely avoided.The precipitation-hardened maraging steel is precipitation-hardened, i.e. adjusted to a specific HRC Rockwell hardness, so that its HRC Rockwell hardness is essentially matched to the HRC Rockwell hardness of the steel, i.e., it has an HRC Rockwell hardness that is up to 11% greater or up to 11% lower, in each case relative to the HRC Rockwell hardness of the carrier body. This can be illustrated by an outer diameter of the tool head body, which remains virtually the same before and after aging, usually becoming less than 0.01% larger or smaller. Because the tool head body has an HRC Rockwell hardness that is up to 11% greater or up to 11% lower than the carrier body according to the standard Rockwell hardness scale HRC, the base body composite also has a substantially more uniform HRC Rockwell hardness overall.Consequently, neither the carrier body nor the tool head body will wear significantly faster than the other, extending the overall service life of the base body assembly and making it more predictable. Furthermore, the base body assembly bears the loads more evenly during use. This further reduces the risk of fractures, cracks, and other structural damage. The fact that the tool head body has an HRC Rockwell hardness that is up to 11% higher or up to 11% lower than the carrier body, measured according to the standard HRC Rockwell hardness scale, is equivalent to the following condition: 0.11·R. T ч (R W o R T ) ч 0.11·R T , where R T the HRC Rockwell hardness of the carrier body measured according to the standard Rockwell hardness scale HRC and R Wthe HRC Rockwell hardness of the tool head body, measured according to the standard Rockwell hardness scale HRC. The HRC Rockwell hardness of the tool head body and the carrier body shall each be measured according to the standard ÖNORM EN ISO 6508-1, edition: 2016-11-15, according to the standard Rockwell hardness scale C within the meaning of this disclosure. With regard to the Rockwell hardness measurement, the tool head body and the carrier body are to be considered as respective test specimens within the meaning of the standard ÖNORM EN ISO 6508-1, edition: 2016-11-15. Typically, five HRC Rockwell hardness values ​​according to the standard Rockwell hardness scale C are to be measured on the carrier base body and on the tool head base body, the respective mean value is to be calculated from these HRC Rockwell hardness measurements and thus the HRC Rockwell hardness of the tool head base body or the carrier base body is to be expressed in the sense of the present disclosure.The HRC Rockwell hardness measurement should generally be performed at suitable locations on the tool head body and the support body in accordance with Section 6 of ÖNORM EN ISO 6508-1, edition: 2016-11-15. However, the specialist will strive to perform a meaningful HRC Rockwell hardness measurement that is representative of both the tool head body and the support body. Typically, precipitation-hardened maraging steel comprises or consists of 17 to 20 mass percent nickel, 8 to 12.5 mass percent cobalt, 3 to 5.2 mass percent molybdenum, 0.15 to 1.8 mass percent titanium, 0.05 to 0.15 mass percent aluminum, 0 to 0.5 mass percent chromium, 0 to 0.5 mass percent copper, 0 to 0.15 mass percent manganese, 0 to 0.1 mass percent silicon, 0 to 0.03 mass percent carbon, the remainder iron and unavoidable impurities such as sulfur and / or phosphorus; the mass percentages are based on the total composition.The steel typically comprises or consists of 0.2 to 0.65 mass percent carbon, 0 to 2.5 mass percent silicon, 0 to 2 mass percent manganese, 0 to 12 mass percent chromium, 0 to 5 mass percent molybdenum, 0 to 3.5 mass percent vanadium, 0 to 1.5 mass percent nickel, 0 to 0.15 mass percent sulfur, the remainder iron and unavoidable impurities such as sulfur and / or phosphorus; the mass percentages are based on the total composition. As the tool head base body is seamlessly bonded to the carrier base body, the latter is connected to the latter without a weld or solder joint and is not form-fitting, forming a monolithic unit. The tool head base body is seamlessly bonded to the carrier base body by being additively built up onto the carrier base body.The base body can be manufactured conventionally, i.e., non-additively, for example, by milling, drilling, and / or grinding. Because the steel contains 0.2 to 0.65 mass percent carbon, it is suitable for forming a martensitic structure with a high HRC Rockwell hardness, for example, 50 HRC. It is hardened and then tempered, which typically increases toughness and adjusts (usually reduces) the HRC Rockwell hardness. However, tempering can also form so-called secondary carbides, which lead to an increase in the HRC Rockwell hardness, i.e., a local HRC Rockwell hardness maximum as a function of the tempering temperature. The conditions 0.11·R. T ч (R W o R T ) ч 0.11·R T , о0.05,·RT ч (RW о RT) ч 0.05·RT, о0.015·R T ч (R W o R T ) ч 0.015·R T, can be adjusted by tempering the steel after hardening to achieve a specific target HRC Rockwell hardness, and by adding the maraging steel to the base body and aging it so that the maraging steel and thus the tool head base body reach the target HRC Rockwell hardness of the steel and thus of the base body, whereby the maraging steel is aged at a temperature that is lower than the temperature at which the steel was tempered. Surprisingly, such an HRC Rockwell hardness adjustment almost completely prevents distortion of the then precipitation-hardened maraging steel. It is sufficient for the person skilled in the art to know that the steel has a carbon content of 0.2 to 0.65 mass percent and that the maraging steel is such, in order to adjust the parameters during hardening, tempering, and aging accordingly in order to achieve one of the conditions specified in the [context unclear]. T ч (R W o RT ) ч 0.11·R T , 0.05·R T ч (R W o R T ) ч 0.05·R T , 0.015·R T ч (R W o R T ) ч 0.015·RT. According to an advantageous further development, the tool head body has a Rockwell hardness of up to 5% greater or up to 5% lower than the carrier body, measured according to the standard Rockwell hardness scale HRC. This further reduces distortion during heat treatment, ensures even more homogeneous wear behavior of the base body composite, and is equivalent to the following condition: о0.05·R T ч (R W o R T ) ч 0.05·R T. At this point, it is expressly stated that it is most preferred if the tool head body has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC that is up to 1.5% greater or up to 1.5% lower than the carrier body, which is equivalent to the following condition: о0.015 RT ч (RW о RT) ч 0.015 RT. Accordingly, RW у RT, preferably RW = RT, represents an optimum. According to an advantageous development, the carrier body has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC in the range of 40 HRC to 45 HRC. This is a special range for the HRC Rockwell hardness of the carrier body, in which the carrier body has a balance between toughness and strength that is advantageous for supporting the tool head body.According to an advantageous development, the tool head base body has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC in the range of 40 HRC to 45 HRC. This is a special range for the HRC Rockwell hardness of the tool head base body, in which the tool head base body has a balance between toughness and strength that is advantageous for machining applications. At this point, it is expressly stated that it is particularly advantageous if the carrier base body has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC in the range of 40 HRC to 45 HRC and the tool head base body has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC in the range of 40 HRC to 45 HRC. According to an advantageous development, the tool head base body has a coolant channel that is spatially curved at least in sections.The coolant channel, which is spatially curved at least in sections, is advantageous for particularly smooth coolant deflection, wherein the coolant channel, which is spatially curved at least in sections, can preferably be connected in a fluid-communicating manner to a preferably provided feed channel of the carrier base body. The fact that the base body composite exhibits virtually no distortion during the heat treatment for precipitation hardening simultaneously means that the coolant channel, which is spatially curved at least in sections, also retains its shape during and after this heat treatment. According to an advantageous development, the tool head base body is equipped with at least one cutting element. The cutting element is preferably made of cemented carbide, which improves the cutting performance.The cutting element can be reversibly detachably attached to the tool head base body, for example, by means of a screw or a clamping claw, or by a material bond, for example, soldered. According to an advantageous development, the tool head base body has at least one insert seat for mounting a cutting element. The cutting element is preferably designed according to the cutting element described above, for example, made of cemented carbide. The insert seat can extend primarily circumferentially or primarily radially with respect to a rotational axis of the tool head base body. According to an advantageous development, the precipitation-hardened maraging steel is overaged.Because it is overaged, precipitation-hardened maraging steel does not exhibit its temperature-dependent maximum HRC Rockwell hardness. This can be easily determined by a specialist who further ages the overaged maraging steel and measures the change in HRC Rockwell hardness. If this increases, the maraging steel would be underaged; if it decreases, it is overaged. Overaging makes precipitation-hardened maraging steel more ductile and thus more robust against impact loads during machining with the base body composite.According to an advantageous further development, the precipitation-hardened maraging steel comprises 17 to 20 mass percent nickel, 8 to 12.5 mass percent cobalt, 3 to 5.2 mass percent molybdenum, 0.15 to 1.8 mass percent titanium, 0.05 to 0.15 mass percent aluminum, 0 to 0.5 mass percent chromium, 0 to 0.5 mass percent copper, 0 to 0.15 mass percent manganese, 0 to 0.1 mass percent silicon, 0 to 0.03 mass percent carbon, the remainder iron and unavoidable impurities. If the precipitation-hardened maraging steel has or consists of this composition, in addition to its reduced tendency to warp with respect to the carrier base body, it is also particularly well suited for additive manufacturing of the tool head base body on the carrier base body.Preferably, the maraging steel consists of 17 to 20 mass percent nickel, 8 to 12.5 mass percent cobalt, 3 to 5.2 mass percent molybdenum, 0.15 to 1.8 mass percent titanium, 0.05 to 0.15 mass percent aluminum, 0 to 0.5 mass percent chromium, 0 to 0.5 mass percent copper, 0 to 0.15 mass percent manganese, 0 to 0.1 mass percent silicon, 0 to 0.03 mass percent carbon, the remainder iron and unavoidable impurities. Particularly preferred is the composition falling within this composition range, standardized composition 1.2709 (material number according to DIN EN 10027-2:2015-07, July 2015, i.e. in mass percent based on the total composition, 17 to 19 nickel, 8.5 to 10 cobalt, 4.5 to 5.2 Mo, 0.8 to 1.2 titanium, maximum 0.03 carbon, maximum 0.1 silicon, maximum 0.15 manganese, maximum 0.25 chromium, balance iron and unavoidable impurities) of the precipitation-hardened maraging steel.According to an advantageous development, the steel comprises 0.2 to 0.65 mass percent carbon, 0.2 to 0.65 mass percent carbon, 0 to 2.5 mass percent silicon, 0 to 2 mass percent manganese, 0 to 12 mass percent chromium, 0 to 5 mass percent molybdenum, 0 to 3.5 mass percent vanadium, 0 to 1.5 mass percent nickel, 0 to 0.15 mass percent sulfur, the remainder iron and unavoidable impurities. If the steel has or consists of this composition, in addition to its reduced tendency to warp, it is dimensionally stable during a heat treatment common to the tool head body. Preferably, the steel consists of 0.2 to 0.65 mass percent carbon, 0.2 to 0.65 mass percent carbon, 0 to 2.5 mass percent silicon, 0 to 2 mass percent manganese, 0 to 12 mass percent chromium, 0 to 5 mass percent molybdenum, 0 to 3.5 mass percent vanadium, 0 to 1.5 mass percent nickel, 0 to 0.15 mass percent sulfur, the remainder iron and unavoidable impurities.Particularly preferred are the standardized compositions 1.2343, 1.2311, and 1.2312 (material numbers according to DIN EN 10027-2:2015-07, July 2015, i.e., in mass percent based on the total composition for "1.2343": 0.38 carbon, 1.1 silicon, 0.4 manganese, 5 chromium, 1.3 molybdenum, 0.4 vanadium; for "1.2311": 0.4 carbon, 1.5 manganese, 1.9 chromium, 0.2 molybdenum; for "1.2312": 0.4 carbon, 0.4 silicon, 1.5 manganese, 1.9 chromium, 0.2 molybdenum, 0.1 sulfur) of the steel falling within this composition range. This object is also achieved by the method according to claim 11.The method for producing a base body composite for a cutting tool comprises the following process steps: a) providing a carrier base body made of a steel with a carbon content of 0.2 to 0.65 mass percent carbon, b) additively building a tool head base body onto the carrier base body using a maraging steel powder, c) precipitation hardening the tool head base body such that the tool head base body has an HRC Rockwell hardness that is up to 11% greater or up to 11% lower than the carrier base body, measured according to the standard Rockwell hardness scale HRC. This method can be used to produce the base body composite according to any one of claims 1 to 9.In this respect, the properties and advantages described with regard to the base body composite are realized analogously; the maraging powder is usually not yet precipitation-hardened before and / or during step b), but otherwise has the same properties described with regard to the maraging steel from which the tool head base body is made. Preferably, the tool head base body is given a Rockwell hardness of up to 5% greater or 5% lower than that of the carrier base body, measured according to the standard Rockwell hardness scale HRC, or a Rockwell hardness of up to 1.5% greater or 1.5% lower than that of the carrier base body. When provided in step a), the carrier base body is preferably manufactured conventionally, for example by grinding, milling, turning, or drilling, and is therefore not additively manufactured. This saves costs and increases the productivity of the process.Preferably, the carrier base body is heated in step b) to a temperature greater than 25°C, preferably to 100°C or more. Preferably, the carrier base body and thus the steel are heated and quenched to martensite formation before step a) and then tempered at a tempering temperature, for example, at 610°C in the case of the standardized composition 1.2343 of the steel, wherein the precipitation hardening in step c) is carried out at a temperature below the tempering temperature, for example, at 590°C for six hours in the case of the standardized composition 1.2709 of the maraging steel, whereby the HRC Rockwell hardness of the steel and thus of the carrier base body is almost completely retained in step c).Selective laser melting can be used for the additive construction of the tool head base body in step b). A powder bed of maraging steel powder is built up layer by layer, and a laser beam selectively melts the maraging steel powder following a 3D model of the tool head base body in order to obtain the shape specified by the 3D model. This creates a seamless, material-to-material bond between the first layer of maraging steel powder and the carrier base body. After melting by the laser beam, the maraging steel powder is cooled, quenched, and can therefore usually be aged immediately afterwards. Electron beam melting of the maraging steel powder, analogous to selective laser beam melting, is also conceivable and possible. The latter is carried out in a vacuum chamber and uses an electron beam instead of a laser beam for melting.Also conceivable and possible is what is known as “binder jetting” in step b), in which a binder containing the maraging steel powder is applied layer by layer to the carrier base body following a 3D model of the tool head base body. After this application of the binder, it is subjected to a sintering process in the applied state, whereby the first layer of maraging steel powder applied in this way is also bonded to the carrier base body in a material-to-material manner. According to an advantageous development of the method, the tool head base body is additively built up in step b) by selective laser melting. According to an advantageous development of the method, the tool head base body is additively built up in step b) to form a coolant channel that is spatially curved at least in sections.According to an advantageous development of the method, the maraging steel powder has the composition defined in claim 9 and the steel has the composition defined in claim 10. According to an advantageous development of the method, the carrier base body in step a) and after step c) each has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC, which is in the range from 40 HRC to 45 HRC. According to an advantageous development of the method, the tool head base body after step c) has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC in the range from 40 HRC to 45 HRC. According to an advantageous development of the method, in step c) the tool head base body is arranged together with the carrier base body in a furnace and is heated together with the tool head base body in the furnace during precipitation hardening.Further advantages and benefits of the invention will become apparent from the following description of exemplary embodiments with reference to the accompanying figure. Fig. 1: Schematic representation of a base body assembly for a cutting tool. Fig. 1 shows a base body assembly 1 as part of a cutting tool 100 in a transparent representation. The base body assembly 1 and thus the cutting tool 100 extend along a virtual axis of rotation 101 and can be driven in rotation relative to this axis. The base body composite 1 comprises a conventionally, i.e. non-additively manufactured carrier base body 2, which is made of a steel of the standardized composition 1.2343 and hardened at 610°C to achieve an HRC Rockwell hardness of 42 HRC (average value of five HRC Rockwell hardness measurements on the carrier base body 2, each measured according to the standard ÖNORM EN ISO 6508-1, edition: 2016-11-15, according to the standard Rockwell hardness scale C).The steel is also tempered. Its HRC Rockwell hardness of 42 is typical for the range 40 to 45 HRC. The steel with the standardized composition 1.2343 is typical for a composition consisting of 17 to 20 mass percent nickel, 8 to 12.5 mass percent cobalt, 3 to 5.2 mass percent molybdenum, 0.15 to 1.8 mass percent titanium, 0.05 to 0.15 mass percent aluminum, 0 to 0.5 mass percent chromium, 0 to 0.5 mass percent copper, 0 to 0.15 mass percent manganese, 0 to 0.1 mass percent silicon, 0 to 0.03 mass percent carbon, the remainder being iron and unavoidable impurities, and thus also typical for the standardized compositions 1.2311 and 1.2312. The base body composite 1 further comprises a tool head base body 3 additively constructed by selective laser melting onto a circular interface 4 of the carrier base body 2.The carrier body 2 and the tool head body 3 are thus seamlessly bonded to form a monolithic unit. During additive assembly at interface 4, the carrier body 2 was heated to 100°C as an example. The tool head body 3 is made of a precipitation-hardened, standardized maraging steel 1.2709; precipitation hardening by aging was carried out after additive assembly at 590°C for 6 hours together with the carrier body 2, which is an example of precipitation hardening at a temperature below the tempering temperature at which the steel from which the carrier body 2 is made was tempered.Through this precipitation hardening, the maraging steel has achieved a Rockwell hardness of 41.6 HRC (average of five Rockwell hardness measurements on the tool head body 3, each measured according to ÖNORM EN ISO 6508-1, edition: November 15, 2016, according to the standard Rockwell hardness scale C). The Rockwell hardness of 41.6 HRC of the precipitation-hardened, standardized maraging steel 1.2709 and thus of the tool head body is exemplary for the 40 HRC to 45 HRC range. The HRC Rockwell hardness of the carrier body 2, and thus of the steel from which it is made, measured according to the standard Rockwell hardness scale HRC, remained essentially unchanged during precipitation hardening, and thus in the range of 40 HRC to 45 HRC, and the maraging steel was precipitation hardened, i.e. overaged, to below its maximum possible HRC Rockwell hardness of approximately 54 HRC for its composition.The precipitation hardened maraging steel is an example of the composition, consisting of 17 to 20 mass percent nickel, 8 to 12.5 mass percent cobalt, 3 to 5.2 mass percent molybdenum, 0.15 to 1.8 mass percent titanium, 0.05 to 0.15 mass percent aluminum, 0 to 0.5 mass percent chromium, 0 to 0.5 mass percent copper, 0 to 0.15 mass percent manganese, 0 to 0.1 mass percent silicon, 0 to 0.03 mass percent carbon, the remainder iron and unavoidable impurities. The tool head body 3 has a 1% lower HRC Rockwell hardness than the carrier body 2 according to the standard Rockwell hardness scale (HRC), i.e., 01%, which is exemplary for the range from 01.5% to 1.5%, and thus also exemplary for the equally narrow ranges of 05% to 5% and 011% to 11%. The maraging steel was overaged to adjust its HRC Rockwell hardness as closely as possible to that of the steel.It was surprisingly found that the outer diameter D of the tool head base body 3, shown as an example in the form of a cylinder, had become only 0.01% smaller compared to the state before the described heat treatment, meaning that the tool head base body 3 is almost distortion-free after the heat treatment. During additive construction, the tool head base body 3 was selectively melted layer by layer from a 3D model of the tool head base body 3 using powder with the standardized composition 1.2709, followed by solidification using a laser beam. The tool head base body 3 was additively constructed by laser melting from the maraging steel powder to form a spatially curved coolant channel 5 and a circumferentially extending insert seat 6. The coolant channel 5 opens in the area of ​​the insert seat 6 for the coolant supply there.A cutting element 7 can be reversibly detachably or firmly secured in the insert seat 6, so that the base body assembly 1 is then equipped with the cutting element. The tool head base body 3 was additively constructed by laser melting from the maraging steel powder in such a way that the coolant channel 5 was connected in a fluid-communicating manner to a feed channel 8 of the carrier base body 2; thus, coolant can enter the base body assembly 1 through the feed channel 8 and exit the coolant channel 5. The base body assembly 1 illustrates a method for its production and also its use as part of the cutting tool 100.The method for producing the base body composite 1 thus comprises the following steps: a) providing the carrier base body 2, b) additively building the tool head base body 3 on the carrier base body 2 using the maraging steel powder, c) precipitation hardening of the tool head base body so that the tool head base body 3 receives an HRC Rockwell hardness that is up to 11% greater or up to 11% lower than that of the carrier base body, measured according to the standard Rockwell hardness scale HRC. The present invention is not limited to the embodiment according to Fig. 1. Further tests were carried out. These have shown that if the condition 0.11·RT χ (R. W o R T ) ч 0.11·R T is not fulfilled, there was a significant distortion with respect to the diameter D, which is also the diameter D of the also circular interface 4; R Tis the HRC Rockwell hardness of the carrier body 2 and R, measured according to the standard Rockwell hardness scale HRC W the HRC Rockwell hardness of the tool head body 3 measured according to the standard Rockwell hardness scale HRC. For example, if a maraging steel powder or other precipitation hardening is used for the additive construction of the tool head body 3, which is so different that the HRC Rockwell hardness of the tool head body 3 after precipitation hardening no longer meets the condition о0.11·R T ч (R W o R T ) ч 0.11·R T Or, for example, if a different steel or other tempering is used for the carrier body 2, so that for this reason the condition о0,11·R T ч (R W o R T ) ч 0.11·R T is no longer fulfilled.

Claims

CLAIMS 1. A base body composite for a cutting tool (100), comprising a carrier base body (2) made of a steel with a carbon content of 0.2 to 0.65 mass percent carbon, and a tool head base body (3) made of a precipitation-hardened maraging steel and seamlessly bonded to the carrier base body (2), wherein the tool head base body (3) has a Rockwell hardness of up to 11% greater or up to 11% lower than the carrier base body (2) according to the standard Rockwell hardness scale HRC.

2. A base body composite according to claim 1, wherein the tool head base body (3) has a Rockwell hardness of up to 5% greater or up to 5% lower than the carrier base body (2) according to the standard Rockwell hardness scale HRC. 3.The base body assembly according to one of the preceding claims, wherein the carrier base body (2) has a Rockwell hardness in the range from 40 HRC to 45 HRC, as measured according to the standard Rockwell hardness scale (HRC).

4. The base body assembly according to one of the preceding claims, wherein the tool head base body (2) has a Rockwell hardness in the range from 40 HRC to 45 HRC, as measured according to the standard Rockwell hardness scale (HRC).

5. The base body assembly according to one of the preceding claims, wherein the tool head base body (3) has a coolant channel (5) that is spatially curved at least in sections.

6. The base body assembly according to one of the preceding claims, wherein the tool head base body (2) is equipped with at least one cutting element (7).

7. The base body assembly according to one of the preceding claims, wherein the tool head base body (2) has at least one insert seat (6) for mounting a cutting element (7). 8.Base body composite according to one of the preceding claims, wherein the precipitation-hardened maraging steel is overaged.

9. A base body composite according to any one of the preceding claims, wherein the precipitation hardened maraging steel comprises: 17 to 20 mass percent nickel, 8 to 12.5 mass percent cobalt, 3 to 5.2 mass percent molybdenum, 0.15 to 1.8 mass percent titanium, 0.05 to 0.15 mass percent aluminum, 0 to 0.5 mass percent chromium, 0 to 0.5 mass percent copper, 0 to 0.15 mass percent manganese, 0 to 0.1 mass percent silicon, 0 to 0.03 mass percent carbon, the remainder iron and unavoidable impurities.

10. A base body composite according to any one of the preceding claims, wherein the steel comprises: 0.2 to 0.65 mass percent carbon, 0 to 2.5 mass percent silicon, 0 to 2 mass percent manganese, 0 to 12 mass percent chromium, 0 to 5 mass percent molybdenum, 0 to 3.5 mass percent vanadium, 0 to 1.5 mass percent nickel, 0 to 0.15 mass percent sulfur, the remainder iron and unavoidable impurities.

11. A method for producing a base body composite (1) for a cutting tool (101), comprising the method steps: a) providing a carrier base body (2) made of a steel with a carbon content of 0.2 to 0.65 mass percent carbon, b) additively building a tool head base body (3) onto the carrier base body (2) using a maraging steel powder, c) precipitation hardening the tool head base body (3) such that the tool head base body (3) has an HRC Rockwell hardness measured according to the standard Rockwell hardness scale HRC that is up to 11% greater or up to 11% lower than the carrier base body (2).

12. The method according to claim 11, wherein in step b), the tool head base body (3) is additively built up to form a coolant channel (5) that is spatially curved at least in sections.The method according to claim 11 or 12, wherein the maraging steel powder has the composition defined in claim 9 and the steel has the composition defined in claim 10.

14. The method according to any one of claims 11 to 13, wherein the carrier base body (2) in step a) and after step c) each has a Rockwell hardness of 40 HRC to 45 HRC, measured according to the standard Rockwell hardness scale HRC.

15. The method according to any one of claims 11 to 14, wherein the tool head base body (3) after step c) has a Rockwell hardness of 40 HRC to 45 HRC, measured according to the standard Rockwell hardness scale HRC.

Images