EP4121571A1 - Method for producing a screw, and screw - Google Patents
Method for producing a screw, and screwInfo
- Publication number
- EP4121571A1 EP4121571A1 EP21716269.2A EP21716269A EP4121571A1 EP 4121571 A1 EP4121571 A1 EP 4121571A1 EP 21716269 A EP21716269 A EP 21716269A EP 4121571 A1 EP4121571 A1 EP 4121571A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- screw
- temperature
- tip
- core
- carbon
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 30
- 229910000734 martensite Inorganic materials 0.000 claims abstract description 16
- 239000000956 alloy Substances 0.000 claims abstract description 10
- 238000010791 quenching Methods 0.000 claims abstract description 10
- 230000000171 quenching effect Effects 0.000 claims abstract description 10
- 229910045601 alloy Inorganic materials 0.000 claims abstract description 8
- 239000012298 atmosphere Substances 0.000 claims abstract description 8
- 229910000975 Carbon steel Inorganic materials 0.000 claims abstract description 5
- 239000010962 carbon steel Substances 0.000 claims abstract description 5
- 238000010438 heat treatment Methods 0.000 claims abstract description 5
- 238000005096 rolling process Methods 0.000 claims abstract description 4
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract 3
- 238000000034 method Methods 0.000 claims description 13
- 229910001563 bainite Inorganic materials 0.000 claims description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 2
- 239000000463 material Substances 0.000 description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 3
- 229910001562 pearlite Inorganic materials 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/78—Combined heat-treatments not provided for above
- C21D1/785—Thermocycling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0093—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for screws; for bolts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21H—MAKING PARTICULAR METAL OBJECTS BY ROLLING, e.g. SCREWS, WHEELS, RINGS, BARRELS, BALLS
- B21H3/00—Making helical bodies or bodies having parts of helical shape
- B21H3/02—Making helical bodies or bodies having parts of helical shape external screw-threads ; Making dies for thread rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/06—Surface hardening
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
- C21D1/20—Isothermal quenching, e.g. bainitic hardening
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D1/76—Adjusting the composition of the atmosphere
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/20—Carburising
- C23C8/22—Carburising of ferrous surfaces
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/80—After-treatment
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B25/00—Screws that cut thread in the body into which they are screwed, e.g. wood screws
- F16B25/001—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed
- F16B25/0021—Screws that cut thread in the body into which they are screwed, e.g. wood screws characterised by the material of the body into which the screw is screwed the material being metal, e.g. sheet-metal or aluminium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16B—DEVICES FOR FASTENING OR SECURING CONSTRUCTIONAL ELEMENTS OR MACHINE PARTS TOGETHER, e.g. NAILS, BOLTS, CIRCLIPS, CLAMPS, CLIPS OR WEDGES; JOINTS OR JOINTING
- F16B33/00—Features common to bolt and nut
- F16B33/06—Surface treatment of parts furnished with screw-thread, e.g. for preventing seizure or fretting
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Definitions
- the invention relates to a method for producing a screw according to the preamble of claim 1, as well as a screw for direct screwing according to the preamble of claim 5.
- EP 3 276 189 A1 describes a screw which, above the screw shaft in the edge area, has a softer bainitic structure than the screw core.
- DE 10 2017 101 931 A1 discloses a screw with a bainitic structure which, in the axial direction, has a bainitic structure in the tip with a lower hardness than in a central region lying in the direction of the head.
- DE 10 2010 055 210 A1 discloses a method for producing a screw with a doubly hardened tip which has a higher carbon content than its tempered martensitic shank area.
- the shaft with the holding area of the thread has a lower tendency to hydrogen embrittlement than the hardened tip.
- the tip of a low-alloy carbon screw is partially carburized, the entire screw is tempered and then the tip is locally hardened again.
- the object of the invention is to provide a faster or more efficient method for producing a screw in which a tip with particularly great hardness can be realized, but the shaft with its head and holding area is less hard and comparatively less susceptible to hydrogen embrittlement is.
- a tip is understood to mean a front region of the screw which extends from the foremost end of the screw in the direction of the head. This is preferably an area which is designed to form a nut thread in a nut part, in particular made of high-strength metallic materials.
- the screw according to the invention is produced by forming a screw from a wire made of low-alloy carbon steel, which in particular has an alloy content of less than 3% of alloy materials. When the screw is manufactured, the thread is rolled on.
- the preferred screw wire is 23MnB4 or 38B2.
- the screw is then heated to an austenitizing temperature, the austenitizing temperature being a temperature at which the respective wire material is in the austenite phase field of its TTT diagram.
- the austenitizing temperature is in particular greater than the As temperature of the wire material.
- the screw After heating to the austenitizing temperature, the screw is quenched to a bainitizing temperature, at which it is held until the screw has a structure containing bainite, especially in the shaft over its cross-section.
- the bainitization temperature is a temperature at which the wire material is in the bainite phase field.
- the quenching duration is chosen so that both ferrite and pearlite formation are prevented during the quenching process.
- the quenching takes place in particular by immersing the screws in a molten salt which is at bainitization temperature.
- a structure containing bainite is present if a structural section under consideration has a significantly measurable bainite content of in particular more than 25%.
- a structural cutout preferably has a size of 0.05 mm 2 .
- the total area of the structural cutouts with a bainite content of more than 25% results in the screw according to the invention in particular a surface area of more than 80% of the cross-sectional area of the screw.
- the screw after the screw has been kept at the bainitizing temperature for a defined period of time, it is cooled below the martensite start temperature, in particular to room temperature, after which the tip of the screw is then locally heated again to an austenitizing temperature. At least the tip of the screw is then subsequently quenched again to below martensite starting temperature, the quenching duration being selected so that the formation of ferrite, pearlite and bainite is largely prevented. As a result, the tip is locally hardened again, especially in the edge zone, whereby an ultra-hard tip can be made available.
- a screw produced according to the invention has a low tendency towards hydrogen embrittlement in the shaft, but can still have an ultra-hard tip.
- the screw can be heated to the austenitizing temperature before the screw is quenched to a bainitizing temperature in a carbon atmosphere that has a carbon content that is higher than the carbon content in the screw, so that a Forms a layer with a higher carbon content than in the core, so that in the edge zone of the screw there is a carbon content that is at least 0.2% greater than in the core area of the screw.
- the screw can be nitrided in the same way. This is particularly useful for wire materials that have a carbon content of less than 0.4%.
- the screw produced in this way can have an insert-bainitic structure in the shaft and head area, in particular in the edge zone, and an ultra-hard martensitic structure in the tip, in particular in the edge zone of the tip.
- the edge zone in particular has a carbon content of 0.6% to 1.5%.
- the screw according to the invention therefore has both great hardness in the tip and great toughness in the shaft, which also shows a low tendency towards hydrogen embrittlement.
- the screw can be tempered after the insert bainitization and after the hardening of the tip.
- the tempering process can preferably take place together with a coating process.
- the coating can be a zinc flake coating.
- the invention relates to a screw with a shaft encompassing the head and a point encompassing the opposite end of the screw, the shaft having a substantially bainitic structure over its cross section and, according to the invention, the screw having a point with a martensitic edge zone.
- the edge zone has a higher carbon content than the core, the difference in concentration being at least 0.2%.
- the shaft can have an essentially tempered bainitic structure in the core and a tempered structure with a higher carbon content than in the core in the edge zone.
- the tip can have a tempered hardened martensitic structure at least in the edge area.
- the screw according to the invention is preferably produced according to the method described above.
- 1 is a schematic sectional view of a screw produced from low-alloy carbon steel by rolling the thread
- FIG 3 shows a schematic sectional view of the screw after the tip has been locally remunerated for use
- FIG. 4 shows a schematic temperature-time diagram of the method according to the invention for setting the screw and tempering the tip for use.
- 1 shows, after a method step, a schematic sectional view of a rolled screw 10 made of conventional screw steel.
- the screw has a shaft 20 encompassing the head and a free screw end which is arranged in the axial direction opposite the head and which is referred to here as the tip 22.
- the screw according to the invention is produced in that, in one process step, the screw is formed from a screw wire made of low-alloy carbon steel, which has an alloy content of less than 3% of alloy materials. In the manufacture of the screw, the thread in particular is rolled on.
- the preferred screw wire is 23MnB4. Such a steel can be processed well in a rolling process.
- edge zone 18 of the tip of the screw 10 a carbon content has been reached which is at least 0.2% greater than in the core of the screw, and in particular between 0.6% and 1.5%.
- the edge zone 12 and the edge zone 18 are only shown schematically in the present illustration and can vary in their depth. As an alternative or in addition to carburizing, nitriding can also take place analogously.
- the screw 10 is quenched to a bainitization temperature, in particular in a molten salt, the bainitization temperature being above the martensite start temperature Ms.
- the screw is kept at the bainitization temperature until the shaft has essentially a bainitic structure 14 over its cross-sectional area.
- the screw 10, according to FIG. 2 has a higher carbon content in the edge layer 12 and in the edge layer 18 than the core.
- An essentially bainitic structure means that at least 80% of the cross-sectional area has a bainitic structure.
- Other microstructures can also be present in isolated cases.
- Fig. 3 shows a schematic sectional view of a screw 10 according to the invention, in which the tip 22 of the screw was locally heated again to an austenitizing temperature and then cooled to a temperature below the martensite start temperature Ms for martensite formation, so that in the tip 22, in particular in the Edge layer 18, a hardened martensitic structure 16 with a carbon content of approx. 1%. This allows an ultra-hard tip to be created.
- FIG. 4 shows a schematic temperature-time diagram of the production method according to the invention.
- the screw is first heated to an austenitizing temperature that is above the A3 temperature. If the wire material does not have a sufficient carbon content of 0.6% to 1.5%, this can be done in a carbon-enriching atmosphere.
- the carbon content of the atmosphere has a higher carbon concentration than the wire material, so that during heating, carbon diffuses from the carbon atmosphere into the edge zone of the screw.
- the screw is then quenched to a bainitizing temperature.
- the bainitization temperature is the temperature at which the wire material is in the bainite phase field of its ZTU diagram.
- the quenching time is chosen so that both ferrite and pearlite formation is prevented during the quenching process.
- the screw is kept at the bainitization temperature until essential parts of the cross section of the screw have a bainite structure.
- the screw is then cooled to room temperature.
- the tip is locally heated again to austenitizing temperature and then quenched again below the martensite start temperature Ms, so that a martensitic structure is created at least in the edge zone of the tip.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Engineering & Computer Science (AREA)
- Heat Treatment Of Articles (AREA)
- Transmission Devices (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
The invention relates to a method for producing a screw (10), having the following steps: a. rolling a screw wire made of low-alloy carbon steel to produce a screw (10) having a thread, b. heating the entire screw (10) to an austenitizing temperature under a carbon atmosphere and/or nitrogen atmosphere and maintaining the temperature, c. quenching the entire screw (10) to a bainitizing temperature and maintaining the bainitizing temperature until the screw has a bainitic structure over its cross section. The invention is characterized in that the screw (10) is subsequently hardened locally at its tip (22), by the tip (22) being heated to an austenitizing temperature and the screw (10) being subsequently quenched to a temperature below the martensite starting temperature (Ms).
Description
Verfahren zur Herstellung einer Schraube und Schraube Method of making a screw and screw
Die Erfindung betrifft ein Verfahren zur Herstellung einer Schraube nach dem Oberbegriff des Anspruchs 1, sowie eine Schraube zur Direktverschraubung nach dem Oberbegriff des Anspruchs 5. The invention relates to a method for producing a screw according to the preamble of claim 1, as well as a screw for direct screwing according to the preamble of claim 5.
Die EP 3 276 189 A1 beschreibt eine Schraube, die über den Schraubenschaft im Randbereich ein gegenüber dem Schraubenkern weicheres bainitisches Gefüge aufweist. Die DE 10 2017 101 931 A1 offenbart eine Schraube mit einem bainitischen Gefüge, das in axialer Richtung in der Spitze ein bainitisches Gefüge mit einer geringeren Härte als in einem in Richtung des Kopfes liegenden Mittelbereich aufweist. EP 3 276 189 A1 describes a screw which, above the screw shaft in the edge area, has a softer bainitic structure than the screw core. DE 10 2017 101 931 A1 discloses a screw with a bainitic structure which, in the axial direction, has a bainitic structure in the tip with a lower hardness than in a central region lying in the direction of the head.
Die DE 10 2010 055 210 A1 offenbart ein Verfahren zur Herstellung einer Schraube mit einer zweifach gehärteten Spitze, die einen höheren Kohlenstoffanteil aufweist als ihr angelassener martensitischer Schaftbereich. Dies hat zur Folge, dass der Schaft mit dem Haltebereich des Gewindes eine geringere Neigung zur Wasserstoffversprödung aufweist als die gehärtete Spitze. Dazu wird die Spitze einer niedrig legierten Kohlenstoffschraube partiell aufgekohlt, die gesamte Schraube angelassen und anschließend die Spitze nochmals lokal gehärtet. DE 10 2010 055 210 A1 discloses a method for producing a screw with a doubly hardened tip which has a higher carbon content than its tempered martensitic shank area. As a result, the shaft with the holding area of the thread has a lower tendency to hydrogen embrittlement than the hardened tip. To do this, the tip of a low-alloy carbon screw is partially carburized, the entire screw is tempered and then the tip is locally hardened again.
Dieses Verfahren ist aufgrund des partiellen Aufkohlens der Schraube kompliziert und kostenintensiv. This process is complicated and expensive because of the partial carburization of the screw.
Es ist Aufgabe der Erfindung, ein schnelleres bzw. ein effizienteres Verfahren zur Herstellung einer Schraube anzugeben, bei der eine Spitze mit besonders großer Härte realisierbar ist, dennoch aber der Schaft mit seinem Kopf und Haltebereich eine geringere Härte aufweist und vergleichsweise weniger anfällig für eine Wasserstoffversprödung ist. Unter Spitze im Sinne der Erfindung wird ein vorderer Bereich der Schraube verstanden, der sich vom vordersten Ende der Schraube in Richtung des Kopfes erstreckt. Bevorzugt ist dies ein Bereich, der dafür ausgelegt ist, ein Muttergewinde in ein Mutterteil, insbesondere aus höherfesten metallischen Werkstoffen, zu furchen.
Die erfindungsgemäße Schraube wird hergestellt, indem eine Schraube aus einem Draht aus niedrig legiertem Kohlenstoffstahl, der insbesondere einen Legierungsanteil von weniger als 3% Anteil von Legierungsstoffen aufweist, geformt wird. Bei der Herstellung der Schraube wird das Gewinde aufgewalzt. Als Schraubendraht wird bevorzugt 23MnB4 oder 38B2 eingesetzt. The object of the invention is to provide a faster or more efficient method for producing a screw in which a tip with particularly great hardness can be realized, but the shaft with its head and holding area is less hard and comparatively less susceptible to hydrogen embrittlement is. In the context of the invention, a tip is understood to mean a front region of the screw which extends from the foremost end of the screw in the direction of the head. This is preferably an area which is designed to form a nut thread in a nut part, in particular made of high-strength metallic materials. The screw according to the invention is produced by forming a screw from a wire made of low-alloy carbon steel, which in particular has an alloy content of less than 3% of alloy materials. When the screw is manufactured, the thread is rolled on. The preferred screw wire is 23MnB4 or 38B2.
Die Schraube wird dann auf eine Austenitisierungstemperatur erwärmt, wobei die Austenitisierungstemperatur eine Temperatur ist, bei der sich der jeweilige Draht-Werkstoff im Austenit-Phasenfeld seines ZTU-Schaubilds befindet. Die Austenitisierungstemperatur ist insbesondere größer als die As- Temperatur des Draht-Werkstoffs. The screw is then heated to an austenitizing temperature, the austenitizing temperature being a temperature at which the respective wire material is in the austenite phase field of its TTT diagram. The austenitizing temperature is in particular greater than the As temperature of the wire material.
Nach dem Erwärmen auf die Austenitisierungstemperatur wird die Schraube auf eine Bainitisierungstemperatur abgeschreckt, auf der sie solange gehalten wird, bis die Schraube, insbesondere im Schaft über ihren Querschnitt, ein bainithaltiges Gefüge aufweist. Die Bainitisierungstemperatur ist eine Temperatur, bei der sich der Draht-Werkstoff im Bainit-Phasenfeld befindet. Die Abschreckdauer ist insbesondere so gewählt, dass sowohl eine Ferrit- als auch eine Perlitbildung während des Abschreckvorgangs unterbunden werden. Das Abschrecken erfolgt insbesondere, indem die Schrauben in eine auf Bainitisierungstemperatur befindliche Salzschmelze getaucht werden. Ein bainithaltiges Gefüge liegt vor, wenn ein betrachteter Gefügeausschnitt einen signifikant messbaren Bainitanteil von insbesondere mehr als 25% aufweist. Ein Gefügeausschnitt weist bevorzugt eine Größe von 0,05 mm2 auf. After heating to the austenitizing temperature, the screw is quenched to a bainitizing temperature, at which it is held until the screw has a structure containing bainite, especially in the shaft over its cross-section. The bainitization temperature is a temperature at which the wire material is in the bainite phase field. In particular, the quenching duration is chosen so that both ferrite and pearlite formation are prevented during the quenching process. The quenching takes place in particular by immersing the screws in a molten salt which is at bainitization temperature. A structure containing bainite is present if a structural section under consideration has a significantly measurable bainite content of in particular more than 25%. A structural cutout preferably has a size of 0.05 mm 2 .
Die Gesamtfläche der Gefügeausschnitte mit einem Bainitanteil von mehr als 25% ergibt in der erfindungsgemäßen Schraube insbesondere einen Flächenanteil von mehr als 80% der Querschnittsfläche der Schraube. The total area of the structural cutouts with a bainite content of more than 25% results in the screw according to the invention in particular a surface area of more than 80% of the cross-sectional area of the screw.
Erfindungsgemäß wird die Schraube, nachdem sie eine definierte Zeitspanne auf Bainitisierungstemperatur gehalten wurde, unter die Martensitstarttemperatur, insbesondere auf Raumtemperatur, abgekühlt, wonach anschließend die Spitze der Schraube wieder lokal auf eine Austenitisierungstemperatur erwärmt wird. Wenigstens die Spitze der Schraube wird dann anschließend wieder auf unter Martensitstartemperatur abgeschreckt, wobei die Abschreckdauer so gewählt ist, dass eine Ferrit-, Perlit- und Bainit-Bildung weitestgehend unterbunden wird.
Dadurch wird die Spitze insbesondere in der Randzone nochmals lokal gehärtet, wodurch eine ultraharte Spitze zur Verfügung gestellt werden kann. According to the invention, after the screw has been kept at the bainitizing temperature for a defined period of time, it is cooled below the martensite start temperature, in particular to room temperature, after which the tip of the screw is then locally heated again to an austenitizing temperature. At least the tip of the screw is then subsequently quenched again to below martensite starting temperature, the quenching duration being selected so that the formation of ferrite, pearlite and bainite is largely prevented. As a result, the tip is locally hardened again, especially in the edge zone, whereby an ultra-hard tip can be made available.
Auf diese Weise weist eine erfindungsgemäß hergestellte Schraube eine geringe Neigung zur Wasserstoffversprödung im Schaft auf, kann aber dennoch eine ultraharte Spitze besitzen. In this way, a screw produced according to the invention has a low tendency towards hydrogen embrittlement in the shaft, but can still have an ultra-hard tip.
Gemäß einer bevorzugten Ausgestaltung kann die Erwärmung der Schraube auf Austenitisierungstemperatur, bevor die Schraube auf eine Bainitisierungstemperatur abgeschreckt wird, in einer Kohlenstoffatmosphäre erfolgen, die einen Kohlenstoffanteil aufweist, der höher als der Kohlenstoffanteil in der Schraube ist, so dass sich in der Randzone der Schraube eine Schicht mit höherem Kohlenstoffanteil als im Kern bildet, so dass sich in der Randzone der Schraube ein Kohlenstoffanteil ergibt, der wenigstens um 0,2% größer ist als im Kernbereich der Schraube. Alternativ dazu kann ein sogenanntes Nitrieren der Schraube analog erfolgen. Dies ist insbesondere für Drahtwerkstoffe, die einen Kohlenstoffanteil von weniger als 0,4% aufweisen, sinnvoll. According to a preferred embodiment, the screw can be heated to the austenitizing temperature before the screw is quenched to a bainitizing temperature in a carbon atmosphere that has a carbon content that is higher than the carbon content in the screw, so that a Forms a layer with a higher carbon content than in the core, so that in the edge zone of the screw there is a carbon content that is at least 0.2% greater than in the core area of the screw. Alternatively, the screw can be nitrided in the same way. This is particularly useful for wire materials that have a carbon content of less than 0.4%.
Dieser Vorgang, bei dem der Kohlenstoff- oder Stickstoffeintrag in die Schraube bei Austenitisierungstemperatur erfolgt, woraufhin anschließend ein Abschrecken auf Bainitisierungstemperatur folgt, wird im Folgenden als Einsatzbainitisieren bezeichnet. Ein so hergestelltes Gefüge wird als einsatzbainitisches Gefüge bezeichnet. This process, in which the carbon or nitrogen is introduced into the screw at austenitizing temperature, followed by quenching to bainitizing temperature, is referred to below as insert bainitizing. A structure produced in this way is referred to as a bainitic structure.
So kann die so gefertigte Schraube im Schaft und Kopfbereich, insbesondere in der Randzone, ein einsatzbainitisches Gefüge und in der Spitze, insbesondere in der Randzone der Spitze, ein ultrahartes martensitisches Gefüge aufweisen. Die Randzone weist insbesondere einen Kohlenstoffanteil von 0,6% bis 1,5% auf. The screw produced in this way can have an insert-bainitic structure in the shaft and head area, in particular in the edge zone, and an ultra-hard martensitic structure in the tip, in particular in the edge zone of the tip. The edge zone in particular has a carbon content of 0.6% to 1.5%.
Für die Direktverschraubung weist die erfindungsgemäße Schraube dadurch sowohl eine große Härte in der Spitze als auch eine große Zähigkeit im Schaft auf, der zudem eine geringe Neigung zur Wasserstoffversprödung zeigt. For direct screwing, the screw according to the invention therefore has both great hardness in the tip and great toughness in the shaft, which also shows a low tendency towards hydrogen embrittlement.
Gemäß einer weiteren Ausgestaltung kann die Schraube nach der Einsatzbainitisierung und nach der Härtung der Spitze angelassen werden. According to a further embodiment, the screw can be tempered after the insert bainitization and after the hardening of the tip.
Bevorzugt kann der Anlassvorgang zusammen mit einem Beschichtungsvorgang erfolgen. The tempering process can preferably take place together with a coating process.
Insbesondere kann die Beschichtung eine Zinklamellenbeschichtung sein.
Die Erfindung betrifft in einem weiteren Aspekt eine Schraube mit einem den Kopf umfassenden Schaft und einer das gegenüberliegende Ende der Schraube umfassenden Spitze, wobei der Schaft über seinen Querschnitt ein im Wesentlichen bainitisches Gefüge aufweist und erfindungsgemäß die Schraube eine Spitze mit einer martensitischen Randzone aufweist. In particular, the coating can be a zinc flake coating. In a further aspect, the invention relates to a screw with a shaft encompassing the head and a point encompassing the opposite end of the screw, the shaft having a substantially bainitic structure over its cross section and, according to the invention, the screw having a point with a martensitic edge zone.
Die Randzone besitzt insbesondere einen höheren Kohlenstoffanteil als der Kern, wobei der Konzentrationsunterschied wenigstens 0,2% beträgt. In particular, the edge zone has a higher carbon content than the core, the difference in concentration being at least 0.2%.
Der Schaft kann im Kern ein im Wesentlichen angelassenes bainitisches Gefüge und in der Randzone ein angelassenes Gefüge mit einem höheren Kohlenstoffanteil als im Kern aufweisen. Die Spitze kann wenigstens im Randbereich ein angelassenes gehärtetes martensitisches Gefüge aufweisen. The shaft can have an essentially tempered bainitic structure in the core and a tempered structure with a higher carbon content than in the core in the edge zone. The tip can have a tempered hardened martensitic structure at least in the edge area.
Die erfindungsgemäße Schraube ist bevorzugt nach dem vorangehend beschriebenen Verfahren hergestellt. The screw according to the invention is preferably produced according to the method described above.
Weitere Vorteile, Merkmale und Anwendungsmöglichkeiten der vorliegenden Erfindung ergeben sich aus der nachfolgenden Beschreibung in Verbindung mit den in den Zeichnungen dargestellten Ausführungsbeispielen. Further advantages, features and possible applications of the present invention emerge from the following description in conjunction with the exemplary embodiments shown in the drawings.
In der Zeichnung bedeutet: In the drawing means:
Fig. 1 eine schematische Schnittansicht einer unter Walzen des Gewindes hergestellten Schraube aus niedrig legiertem Kohlenstoffstahl; 1 is a schematic sectional view of a screw produced from low-alloy carbon steel by rolling the thread;
Fig. 2 eine schematische Schnittansicht der Schraube nach der Einsatzbainitisierung; 2 shows a schematic sectional view of the screw after insert bainitization;
Fig. 3 eine schematische Schnittansicht der Schraube nach der lokalen Einsatzvergütung der Spitze, und 3 shows a schematic sectional view of the screw after the tip has been locally remunerated for use, and
Fig. 4 ein schematisches Temperatur-Zeit-Diagramm des erfindungsgemäßen Verfahrens der Fierstellung der Schraube und Einsatzvergütens der Spitze.
Fig. 1 zeigt nach einem Verfahrensschritt eine schematische Schnittansicht einer gewalzten Schraube 10 aus herkömmlichem Schraubenstahl. Die Schraube weist einen den Kopf umfassenden Schaft 20 und einen in Axialrichtung gegenüber dem Kopf angeordneten freien Schraubenende liegenden Teil auf, der vorliegend als Spitze 22 bezeichnet ist. Die erfindungsgemäße Schraube wird hergestellt, indem in einem Verfahrensschritt die Schraube aus einem Schraubendraht aus niedrig legiertem Kohlenstoffstahl, der einen Legierungsanteil von weniger als 3% an Legierungsstoffen aufweist, geformt wird. Bei der Herstellung der Schraube wird insbesondere das Gewinde aufgewalzt. Als Schraubendraht wird bevorzugt 23MnB4 eingesetzt. Ein solcher Stahl kann in einem Walzprozess gut verarbeitet werden. 4 shows a schematic temperature-time diagram of the method according to the invention for setting the screw and tempering the tip for use. 1 shows, after a method step, a schematic sectional view of a rolled screw 10 made of conventional screw steel. The screw has a shaft 20 encompassing the head and a free screw end which is arranged in the axial direction opposite the head and which is referred to here as the tip 22. The screw according to the invention is produced in that, in one process step, the screw is formed from a screw wire made of low-alloy carbon steel, which has an alloy content of less than 3% of alloy materials. In the manufacture of the screw, the thread in particular is rolled on. The preferred screw wire is 23MnB4. Such a steel can be processed well in a rolling process.
Fig. 2 zeigt eine schematische Schnittansicht der Schraube 10. 2 shows a schematic sectional view of the screw 10.
Die Schraube 10 wurde zum Erreichen des in Fig. 2 gezeigten Zustands in einer Kohlenstoff- Atmosphäre, die einen größeren Kohlenstoffanteil als die Schraube 10 aufweist, auf Austenitisierungstemperatur erwärmt und der Kohlenstoff-Atmosphäre so lange ausgesetzt, bis in der Randzone 12 des Schafts und in der Randzone 18 der Spitze der Schraube 10 ein Kohlenstoffanteil erreicht wurde, der um wenigstens 0,2% größer ist als im Kern der Schraube, und der insbesondere zwischen 0,6% und 1,5% liegt. Die Randzone 12 und die Randzone 18 sind in der vorliegenden Darstellung nur schematisch abgebildet und können in ihrer Tiefe variieren. Alternativ oder zusätzlich zum Aufkohlen kann auch ein Nitrieren analog stattfinden. In order to achieve the state shown in FIG the edge zone 18 of the tip of the screw 10 a carbon content has been reached which is at least 0.2% greater than in the core of the screw, and in particular between 0.6% and 1.5%. The edge zone 12 and the edge zone 18 are only shown schematically in the present illustration and can vary in their depth. As an alternative or in addition to carburizing, nitriding can also take place analogously.
Nach Erreichen der gewünschten Kohlenstoffsättigung in der Randzone 12 und der Randzone 18 wird die Schraube 10 insbesondere in einer Salzschmelze auf eine Bainitisierungstemperatur abgeschreckt, wobei die Bainitisierungstemperatur über der Martensitstarttemperatur Ms liegt. Die Schraube wird so lange auf Bainitisierungstemperatur gehalten, bis der Schaft über seine Querschnittsfläche im Wesentlichen ein bainitisches Gefüge 14 aufweist. Die Schraube 10, gemäß Fig. 2, weist in der Randschicht 12 und in der Randschicht 18 einen höheren Kohlenstoffanteil als der Kern auf. Ein im Wesentlichen bainitisches Gefüge bedeutet, dass wenigstens 80% der Querschnittsfläche ein bainitisches Gefüge aufweisen. Vereinzelt können auch andere Gefügestrukturen vorliegen. After the desired carbon saturation has been reached in the edge zone 12 and the edge zone 18, the screw 10 is quenched to a bainitization temperature, in particular in a molten salt, the bainitization temperature being above the martensite start temperature Ms. The screw is kept at the bainitization temperature until the shaft has essentially a bainitic structure 14 over its cross-sectional area. The screw 10, according to FIG. 2, has a higher carbon content in the edge layer 12 and in the edge layer 18 than the core. An essentially bainitic structure means that at least 80% of the cross-sectional area has a bainitic structure. Other microstructures can also be present in isolated cases.
Fig. 3 zeigt eine schematische Schnittansicht einer erfindungsgemäßen Schraube 10, bei der die Spitze 22 der Schraube nochmals lokal auf eine Austenitisierungstemperatur erwärmt wurde und anschließend zur Martensitbildung auf eine Temperatur unter der Martensitstarttemperatur Ms abgekühlt wurde, so dass in der Spitze 22, insbesondere in der Randschicht 18, ein gehärtetes martensitisches Gefüge 16
mit einem Kohlenstoffanteil von ca. 1% vorliegt. Dadurch kann eine ultraharte Spitze geschaffen werden. Fig. 3 shows a schematic sectional view of a screw 10 according to the invention, in which the tip 22 of the screw was locally heated again to an austenitizing temperature and then cooled to a temperature below the martensite start temperature Ms for martensite formation, so that in the tip 22, in particular in the Edge layer 18, a hardened martensitic structure 16 with a carbon content of approx. 1%. This allows an ultra-hard tip to be created.
Fig. 4 zeigt ein schematisches Temperatur-Zeit-Diagramm des erfindungsgemäßen Herstellungsverfahrens. Die Schraube wird zuerst auf eine Austenitisierungstemperatur erwärmt, die über der A3 Temperatur liegt. Weist der Draht-Werkstoff keinen ausreichenden Kohlenstoffgehalt von 0,6% bis 1,5% auf, kann dies in einer Kohlenstoff-anreichernden Atmosphäre erfolgen. Der Kohlenstoffanteil der Atmosphäre weist dabei eine höhere Kohlenstoffkonzentration als der Drahtwerkstoff auf, so dass während des Erwärmens Kohlenstoff von der Kohlenstoffatmosphäre in die Randzone der Schraube eindiffundiert. 4 shows a schematic temperature-time diagram of the production method according to the invention. The screw is first heated to an austenitizing temperature that is above the A3 temperature. If the wire material does not have a sufficient carbon content of 0.6% to 1.5%, this can be done in a carbon-enriching atmosphere. The carbon content of the atmosphere has a higher carbon concentration than the wire material, so that during heating, carbon diffuses from the carbon atmosphere into the edge zone of the screw.
Anschließend wird die Schraube auf eine Bainitisierungstemperatur abgeschreckt. Die Bainitisierungstemperatur ist die Temperatur, bei der sich der Draht-Werkstoff im Bainit-Phasenfeld seines ZTU-Diagramms befindet. Die Abschreckdauer ist so gewählt, dass sowohl eine Ferrit- als auch eine Perlitbildung während des Abschreckvorgangs unterbunden ist. Die Schraube wird so lange auf Bainitisierungstemperatur gehalten, bis wesentliche Teile des Querschnitts der Schraube ein Bainitgefüge aufweisen. Anschließend wird die Schraube auf Raumtemperatur abgekühlt. The screw is then quenched to a bainitizing temperature. The bainitization temperature is the temperature at which the wire material is in the bainite phase field of its ZTU diagram. The quenching time is chosen so that both ferrite and pearlite formation is prevented during the quenching process. The screw is kept at the bainitization temperature until essential parts of the cross section of the screw have a bainite structure. The screw is then cooled to room temperature.
Nachdem die entsprechend hergestellte Schraube auf Raumtemperatur RT abgekühlt wurde, wird die Spitze lokal wieder auf Austenitisierungstemperatur erwärmt und anschließend wieder unter die Martensitstarttemperatur Ms abgeschreckt, so dass ein martensitisches Gefüge wenigstens in der Randzone der Spitze entsteht.
After the screw produced accordingly has cooled to room temperature RT, the tip is locally heated again to austenitizing temperature and then quenched again below the martensite start temperature Ms, so that a martensitic structure is created at least in the edge zone of the tip.
Claims
1. Verfahren zur Herstellung einer Schraube (10) mit folgenden Schritten: a. Walzen eines Schraubendrahts aus niedrig legiertem Kohlenstoffstahl zur Herstellung einer Schraube (10) mit einem Gewinde b. Erwärmen der gesamten Schraube (10) auf eine Austenitisierungstemperatur unter Kohlenstoffatmosphäre und/oder Stickstoffatmosphäre und Halten der Temperatur c. Abschrecken der gesamten Schraube (10) auf eine Bainitisierungstemperatur und Halten der Bainitisierungstemperatur, bis die Schraube über ihren Querschnitt ein bainithaltiges Gefüge aufweist, dadurch gekennzeichnet, d. dass anschließend die Schraube (10) an ihrer Spitze (22) lokal gehärtet wird, indem die Spitze (22) auf eine Austenitisierungstemperatur erwärmt wird und die Schraube (10) anschließend auf eine Temperatur unter Martensitstarttemperatur (Ms) abgeschreckt wird. 1. Method for producing a screw (10) with the following steps: a. Rolling a screw wire made of low-alloy carbon steel to produce a screw (10) with a thread b. Heating the entire screw (10) to an austenitizing temperature under a carbon atmosphere and / or nitrogen atmosphere and maintaining the temperature c. Quenching the entire screw (10) to a bainitizing temperature and maintaining the bainitizing temperature until the screw has a structure containing bainite over its cross-section, characterized in that d. that then the screw (10) is locally hardened at its tip (22) by heating the tip (22) to an austenitizing temperature and then quenching the screw (10) to a temperature below martensite start temperature (M s ).
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Kohlenstoffatmosphäre einen höheren Kohlenstoffgehalt als die Schraube aufweist und/oder dass die Stickstoffatmosphäre einen höheren Stickstoffgehalt als die Schraube aufweist. 2. The method according to claim 1, characterized in that the carbon atmosphere has a higher carbon content than the screw and / or that the nitrogen atmosphere has a higher nitrogen content than the screw.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Schraube so lange in der Kohlenstoffatmosphäre auf Austenitisierungstemperatur gehalten wird, bis die Randzone (12, 18) der Schraube einen Kohlenstoffanteil aufweist, der um wenigstens 0,2% größer ist als der Kohlenstoffanteil im Kern.
3. The method according to claim 1 or 2, characterized in that the screw is kept in the carbon atmosphere at austenitizing temperature until the edge zone (12, 18) of the screw has a carbon content that is at least 0.2% greater than that Carbon content in the core.
4. Verfahren nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Schraube (10) angelassen wird. 4. The method according to any one of the preceding claims, characterized in that the screw (10) is tempered.
5. Schraube (10) umfassend einen gewindetragenden Schaft (20) und eine Spitze (22), wobei der Schaft (20) im Kern ein im Wesentlichen bainitisches Gefüge aufweist, dadurch gekennzeichnet, dass die Spitze (22) wenigstens in ihrer Randzone (18) im Wesentlichen aus einem gehärteten martensitischen Gefüge besteht. 5. Screw (10) comprising a thread-bearing shaft (20) and a tip (22), the shaft (20) having a substantially bainitic structure in the core, characterized in that the tip (22) at least in its edge zone (18 ) consists essentially of a hardened martensitic structure.
6. Schraube nach Anspruch 5, dadurch gekennzeichnet, dass die Schraube (10) in der Randzone (12, 18) ein Gefüge mit einem höheren Kohlenstoffanteil als im Kern aufweist. 6. Screw according to claim 5, characterized in that the screw (10) in the edge zone (12, 18) has a structure with a higher carbon content than in the core.
7. Schraube nach Anspruch 5 oder 6, dadurch gekennzeichnet, dass der Schaft im Kern ein im Wesentlichen angelassenes bainitisches Gefüge und in der Randzone (12) ein angelassenes Gefüge mit einem höheren Kohlenstoffanteil als im Kern aufweist, wobei die Spitze (22) wenigstens im Randbereich (18) ein angelassenes gehärtetes martensitisches Gefüge aufweist. 7. Screw according to claim 5 or 6, characterized in that the shaft has a substantially tempered bainitic structure in the core and a tempered structure with a higher carbon content than in the core in the edge zone (12), the tip (22) at least in the Edge area (18) has a tempered hardened martensitic structure.
8. Schraube nach einem der vorangehenden Ansprüche 5 bis 7, dadurch gekennzeichnet, dass die Schraube (10) nach dem Verfahren nach einem der Ansprüche 1 bis 4 hergestellt ist.
8. Screw according to one of the preceding claims 5 to 7, characterized in that the screw (10) is produced according to the method according to one of claims 1 to 4.
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DE102020107194.9A DE102020107194A1 (en) | 2020-03-16 | 2020-03-16 | Method of making a screw and screw |
PCT/EP2021/056712 WO2021185853A1 (en) | 2020-03-16 | 2021-03-16 | Method for producing a screw, and screw |
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DE19540848A1 (en) | 1995-10-30 | 1997-05-28 | Hettich Ludwig & Co | Screw and process for its manufacture |
US6109851A (en) * | 1999-01-13 | 2000-08-29 | Illinois Tool Works Inc. | Screws having selected heat treatment and hardening |
DE10033471C1 (en) | 2000-07-10 | 2001-12-06 | Sfs Ind Holding Ag Heerbrugg | Self-boring screw made from stainless steel used in the building industry has a shaft made from two sections of stainless steel connected together |
DE10315957A1 (en) | 2003-04-08 | 2004-10-28 | Ejot Gmbh & Co. Kg | Screw with a partially hardened functional tip and process for its manufacture |
TWI254656B (en) * | 2004-05-28 | 2006-05-11 | Fwu Kuang Entpr Co Ltd | Manufacture method for forging component with 14.99 grade tension |
DE102010055210A1 (en) | 2010-12-20 | 2012-06-21 | Ejot Gmbh & Co. Kg | Low alloy carbon steel screw and method of making such a screw |
DE102011055497A1 (en) * | 2011-11-18 | 2013-05-23 | Kamax Holding Gmbh & Co. Kg | Ultra-high-strength screw with high yield ratio |
EP2746419A1 (en) * | 2012-12-20 | 2014-06-25 | Sandvik Intellectual Property AB | Bainitic steel for rock drilling component |
EP3276189B1 (en) | 2016-07-29 | 2020-03-25 | KAMAX Holding GmbH & Co. KG | High-strength screw including an unhardening layer |
DE102017101931B4 (en) | 2017-02-01 | 2022-05-05 | Kamax Holding Gmbh & Co. Kg | High strength screw with a softened threaded end |
CN108103297B (en) * | 2018-02-09 | 2019-06-21 | 艾普零件制造(苏州)股份有限公司 | A kind of heat treatment method of electric tool high-strength bolt |
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- 2021-03-16 JP JP2022554596A patent/JP2023529250A/en active Pending
- 2021-03-16 EP EP21716269.2A patent/EP4121571A1/en active Pending
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CN115605619A (en) | 2023-01-13 |
MX2022010914A (en) | 2023-01-18 |
CA3172948A1 (en) | 2021-09-23 |
DE102020107194A1 (en) | 2021-09-16 |
KR20220151653A (en) | 2022-11-15 |
TW202136655A (en) | 2021-10-01 |
BR112022018258A2 (en) | 2022-10-25 |
JP2023529250A (en) | 2023-07-10 |
TWI816092B (en) | 2023-09-21 |
WO2021185853A1 (en) | 2021-09-23 |
US20230136145A1 (en) | 2023-05-04 |
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