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EP4247993B1 - Composant en acier allié b-zr - Google Patents

Composant en acier allié b-zr

Info

Publication number
EP4247993B1
EP4247993B1 EP22826100.4A EP22826100A EP4247993B1 EP 4247993 B1 EP4247993 B1 EP 4247993B1 EP 22826100 A EP22826100 A EP 22826100A EP 4247993 B1 EP4247993 B1 EP 4247993B1
Authority
EP
European Patent Office
Prior art keywords
steel
gew
component
depth
component according
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.)
Active
Application number
EP22826100.4A
Other languages
German (de)
English (en)
Other versions
EP4247993A1 (fr
Inventor
Ali SOLIMANI
Matthew GALLER
Robert KIENREICH
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Voestalpine Wire Rod Austria GmbH
Kamax Holding GmbH and Co KG
Original Assignee
Voestalpine Wire Rod Austria GmbH
Kamax Holding GmbH and Co KG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Voestalpine Wire Rod Austria GmbH, Kamax Holding GmbH and Co KG filed Critical Voestalpine Wire Rod Austria GmbH
Publication of EP4247993A1 publication Critical patent/EP4247993A1/fr
Application granted granted Critical
Publication of EP4247993B1 publication Critical patent/EP4247993B1/fr
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0087—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for chains, for chain links
    • 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
    • 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
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • 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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • 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
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
    • C21D2211/005—Ferrite
    • 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
    • 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
    • C21D2211/009—Pearlite

Definitions

  • the invention relates to a component with a steel component, in which the steel is alloyed with, among other things, boron (hereinafter also "B").
  • B boron
  • the invention relates to a fastening element such as a screw or a nut.
  • boron is often used as a cost-effective alloying element to improve through-hardenability.
  • Steels alloyed with boron are used, for example, in WO 2021/009705 A1 and the WO 2008/142275 A2 described.
  • EP 3 078 758 A1 describes a steel wire for bolts, consisting of C: 0.20 to 0.35%; Si: 0.01% or more; Mn: 0.3 to 1.50; P: more than one and 0.020% or less; S: more than 0% and 0.020% or less; Cr: 0.10 to 1.5%; Al: 0.01 to 0.10%; B: 0.0005 to 0.005%; N: 0.001% or more; and at least one element of Ti: 0.02 to 0.10% and Nb: 0.02 to 0.10%, the balance being iron and unavoidable impurities, wherein when a proportion of a B content at D 0 /4 in the steel wire for bolts is 100%, where D 0 is a diameter of the steel wire for bolts, a ratio of a B content at a surface of the steel wire for bolts is 75% or less on average, and a difference between a maximum value and a minimum value of the ratio is 25% or less.
  • components made of boron-alloyed steels such as screws or nuts, often show a decrease in hardness in the edge area after heat treatment, in particular an isothermal heat treatment in a salt bath to achieve a bainitic structure, especially to a depth of up to 300 ⁇ m below the surface, which limits the applicability for high-strength and ultra-high-strength products, such as high-strength and ultra-high-strength screws.
  • steels containing boron are alloyed with additional titanium and aluminum to keep the boron in the dissolved state and prevent it from precipitating as nitrides, carbides, carbonitrides, silicides, or oxides.
  • additional titanium and aluminum to keep the boron in the dissolved state and prevent it from precipitating as nitrides, carbides, carbonitrides, silicides, or oxides.
  • this is not sufficient to reduce the hardness inhomogeneity in the edge region described above.
  • the present invention is therefore based on the object of reducing the hardness loss in the edge region of components made of boron-alloyed steels.
  • the composition according to the invention in particular the zirconium added to the B-containing steel, in combination with the other alloying elements in the component according to the invention with a steel component, counteracts the loss of hardness in the edge region, especially when the steel component is heat-treated.
  • Another surprising advantage of the component according to the invention with a steel component is the improved resistance to hydrogen embrittlement. Surprisingly, significantly higher strengths can be achieved in this way.
  • fasteners which usually exhibit high and frequently dynamic axial stresses, improving the hardness in the edge region and also reducing hydrogen embrittlement are particularly advantageous, since the fasteners, which can be screws or nuts, for example, are essential for many assemblies.
  • a failure of a fastener can have drastic consequences for humans or machines, such as in the case of a bridge screw, a chassis screw, an engine head screw, or the like.
  • the invention can thus also relate to a vehicle, an engine, a cylinder head, a chassis assembly, or a battery assembly with a component according to the invention, in particular a fastener.
  • the loss of hardness in the edge region of the components can be particularly effectively reduced. Furthermore, hydrogen embrittlement of the steel is significantly reduced.
  • the components Mo, Ni, Cu, and Ca are optional, i.e., they may not be present independently of one another, or, if present, they may be present independently of one another in the steel in the specified amounts of, for example, 0.01–0.20 wt% Mo, 0.01–0.50 wt% Ni, 0.01–0.50 wt% Cu, and/or 0.0010–0.0100 wt% Ca.
  • the components Mo, Ni, Cu, and Ca are present independently of one another in the steel.
  • the steel contains 0.01 - 0.20 wt% Mo, 0.01 - 0.50 wt% Ni, 0.01 - 0.50 wt% Cu and/or 0.0010 - 0.0100 wt% Ca, more preferably 0.01 - 0.16 wt% Mo, 0.01 - 0.40 wt% Ni, 0.01 - 0.30 wt% Cu and/or 0.0010 - 0.0080 wt% Ca.
  • the components Bi, Co, Nb, Pb, Se, Te, W, As, Ta, Ce, Sn, Sb, Hf, and/or lanthanides may also optionally be included in the steel, i.e., they may be included or not included independently of one another. If included, they may be included independently of one another, preferably in the specified amounts.
  • Zirconium is a microalloying element in the steel of the component according to the invention, ie it develops in very small quantities, especially below of 0.05 wt.% has an effect.
  • Boron, titanium, and vanadium are also microalloying elements.
  • zirconium works in conjunction with the other alloying elements, for example, vanadium.
  • the B content in the steel at a depth of 5 - 60 ⁇ m is ⁇ 80%, preferably ⁇ 90%, of the B content in the steel at a depth of 500 ⁇ m (micrometers), with the depth being measured perpendicular to the steel surface.
  • the B content at any point at a depth of 5 - 60 ⁇ m is ⁇ 80% of the B content in the steel at a depth of 500 micrometers.
  • the minimum B content in the steel at a depth of 5 - 60 ⁇ m is ⁇ 80% of the boron content in the steel at a depth of 500 ⁇ m, preferably ⁇ 90%, particularly preferably ⁇ 95%.
  • the boron content refers to the concentration of boron in weight percent, based on the total weight of the steel. Since the value of, for example, ⁇ 80% is a relative value of two B contents, the B content does not have to be expressed in weight percent, but can also be expressed in volume or atomic percent, for example.
  • the B content is determined according to the invention using GDOES (Glow Discharge Optical Emission Spectroscopy) (apparatus: GDA 750 HR from Spectruma Analytik GmbH).
  • GDOES Gas Discharge Optical Emission Spectroscopy
  • the surface of the sample material (steel) is ablated using an Ar plasma, and the sample atoms are brought into the gas phase (cathode sputtering) and then quantitatively determined spectroscopically.
  • the B content is measured spectroscopically at every depth, for example, over a depth range of 0 - 500 ⁇ m.
  • the measurement result is a so-called B depth profile.
  • the B content is determined at every depth, for example, over a depth range of 0 - 500 ⁇ m.
  • the ratio is then determined by dividing the B contents at a specific depth (e.g. 10 ⁇ m) and at a depth of 500 ⁇ m, thus determining the percentage value, which according to the invention is ⁇
  • the boron content in the steel at a depth of 140-220 ⁇ m is preferably ⁇ 80% of the boron content in the steel at a depth of 500 ⁇ m.
  • the boron content is independently preferably ⁇ 90%, further preferably ⁇ 95%, further preferably ⁇ 98%, even more preferably ⁇ 100%, most preferably 100-1000% of the boron content of the steel at a depth of 500 ⁇ m, with the depth being measured perpendicular to the steel surface.
  • the boron content (B concentration) in the steel is 0.0030 - 0.0033 wt% at a depth of 5 - 60 ⁇ m and 0.0033 wt% at a depth of 500 ⁇ m, that would be 90.9% - 100%.
  • the other chemical elements in the steel are measured, as usual, using conventional optical emission spectrometry on the surface of a cross-section of the steel component (so-called product analysis).
  • product analysis optical emission spectrometry on the surface of a cross-section of the steel component
  • the heat treatment or tempering at the end of the manufacturing process in particular salt bath tempering, which leads to these advantageous properties in the edge region of the steel component in the component according to the invention, is advantageous for the low or non-existent drop in boron concentration.
  • the edge area is understood to be the area at a depth of 0 - 300 micrometers, measured from the steel surface.
  • the zirconium in particular, in combination with the other alloying elements, counteracts the decrease in hardness in the edge region and leads to a reduction in hydrogen embrittlement in the edge region.
  • an impurity is understood to mean an element present in an amount of ⁇ 0.01 wt.%.
  • the steel contains unavoidable impurities, each in an amount of ⁇ 0.01 wt.%.
  • the hardness drop in the edge region of the components can be particularly effectively reduced if the ratio of (Zr + Ti + Al) to N is in a range from 2.7 to 150, more preferably 2.8 to 130, particularly preferably 3 to 100.
  • the respective weight percentages of Zr, Ti, Al, and N are used in the aforementioned formula.
  • the component according to the invention with a component made of steel is preferably a fastening means, particularly preferably selected from the group consisting of screws, nuts, rivets, bolts and chains.
  • a steel component within the meaning of the invention can be understood in particular to mean that at least a portion of the component, i.e., a volume region, is made of steel. It is preferred that the steel component constitutes ⁇ 80 wt.%, more preferably ⁇ 90 wt.%, particularly preferably ⁇ 95 wt.% of the component. This means that the component consists of ⁇ 80 wt.%, more preferably ⁇ 90 wt.%, particularly preferably ⁇ 95 wt.% steel. This allows particularly good mechanical strength of the component, in particular of the fastening means, to be achieved. In order to increase mechanical strength, it is particularly preferred if the steel component is made in one piece. "Integral" can be understood in particular to mean that at least the one-piece part has been created in a forming process and/or is continuous.
  • the component according to the invention in particular a screw, is preferably a high-strength or ultra-high-strength component, preferably with strengths ⁇ 800 MPa (so-called high-strength components), particularly preferably over 1200 MPa, further preferably ⁇ 1400 MPa (so-called ultra-high-strength components), particularly preferably 1200-1900 MPa, in particular 1400-1900 MPa.
  • Preferred high-strength and ultra-high-strength components are high-strength or ultra-high-strength screws, nuts, chain drives, formed components, and/or structural components.
  • the component according to the invention, in particular the high-strength or ultra-high-strength component is preferably a welded component, an additively manufactured component, or a case-hardened component.
  • the component or the steel is heat-treated, a so-called tempering, for example by salt bath tempering, in order to establish a preferred microstructure.
  • the microstructure of the steel is ⁇ 70 vol. %, more preferably ⁇ 80 vol. %, particularly preferably ⁇ 90 vol. % bainitic and/or martensitic, in particular after tempering such as heat treatment.
  • the proportion of the microstructure in volume percent can be determined, for example, in microscopic images of micrographs, since the areas reflect the volumes on average over several micrographs. For this purpose, the areas are determined in several micrographs and the arithmetic mean is calculated.
  • the steel microstructure is ⁇ 70 wt.%, more preferably ⁇ 80 wt.%, particularly preferably ⁇ 90 wt.% bainitic and/or martensitic.
  • the proportion of austenite (residual austenite) is also preferably ⁇ 20 vol.% or wt.%, in particular ⁇ 10 vol.% or wt.%.
  • These microstructures impart particularly high strength and toughness to the component according to the invention. They can be subjected to high and often dynamic axial stress.
  • the microstructure of the component according to the invention is preferably ⁇ 90 vol.% ferritic and/or pearlitic.
  • the structure of the component according to the invention before tempering is ⁇ 90 wt.% ferritic and/or pearlitic.
  • the component according to the invention is further preferably a formed component.
  • a formed component is understood, in particular, to be a component that has been formed by means of a forming step, in particular a cold forming process. Reducing hydrogen embrittlement is particularly advantageous for a formed component without heat treatment, because formed components already exhibit a certain degree of brittleness due to the accumulated forest dislocations (e.g., two or more dislocations that collide transversely or perpendicularly with each other on different slip planes).
  • This structural component within the meaning of the invention exists in particular when the component is a load-bearing component.
  • This structural component has, in particular, two load introduction sections, which advantageously have load-introducing structures, such as mounting recesses or openings, and a transmission area arranged between the load introduction sections, which can and/or transmits a load, in particular a bending load and/or tensile load, from one load introduction section to the other load introduction section.
  • the improvement in resistance to hydrogen embrittlement is attributed to, without being bound by the invention, the fact that additional bonding points for diffusible hydrogen are created in the component in the microstructure, in particular a heat-treated microstructure of the steel, in particular by precipitation-forming elements such as Al, Cu, Mo, V, Zr, Ti, B with C, N, O, Si and/or due to the microstructure adjusted by heat treatment.
  • Fasteners can in particular be force-locking fasteners, such as screws, bolts or nuts.
  • Force-locking fasteners are characterized in particular by the fact that they have a threaded section for clamping or fastening, in particular with an external thread or an internal thread.
  • the threaded section can therefore be an external thread or an internal thread.
  • this threaded section is introduced into a component of the fastener which is made of steel.
  • the fastener can expediently have a shank region. This shank region can be formed adjacent to the threaded section and/or a drive region, in particular a head, of the fastener.
  • the shank region can be threadless and/or formed as a cylindrical section.
  • the diameter of the shank can be greater than, less than, or equal to the thread diameter in the threaded section.
  • the screws are advantageously high-strength or ultra-high-strength screws.
  • the component is a high-strength or ultra-high-strength screw.
  • a high-strength screw is understood to be a screw with a tensile strength of at least 800 MPa.
  • High-strength screws are, for example, screws of strength classes 8.8, 10.9, and 12.9.
  • the strength classes of the invention correspond to ISO 898-1 in the version valid as of January 2021.
  • An ultra-high-strength screw is understood to be a screw with a tensile strength, in particular of at least 1200 MPa and/or advantageously of at least 1400 MPa.
  • Ultra-high-strength screws include, for example, screws in strength classes 12.8, 12.9, 14.8, 14.9, 15.8, 15.9, 16.8, 16.9, 17.8, and 12.8U, 12.9U, 14.8U, 14.9U, 15.8U, 15.9U, 16.8U, and 17.8U.
  • a high-strength screw is a screw that is at least high-strength, but can also be ultra-high-strength. Preferably, it is a high-strength or ultra-high-strength screw with a strength of over 1000 MPa.
  • the screw can have a head with tool engagement surfaces, whereby these tool engagement surfaces together form, in particular, an internal or external hexagon.
  • the preferred method according to the invention has the advantage of a resource-saving and cost-efficient process route, since, for example, a wire rod can be processed directly without the need for intermediate GKZ annealing.
  • the establishment of a ferrite-pearlite microstructure in the wire rod state can be achieved by means of TM rolling (thermomechanical rolling).
  • thermomechanical rolling is carried out in step b).
  • Thermomechanical rolling in which the material is rolled to a final forming temperature in a range of Ar 3 - 50 °C and + 100 °C, where Ar 3 in the Fe-C diagram is referred to as the austenite-proeutectoid transformation temperature.
  • GKZ annealing refers to heating with the aim of forming spheroidal cementite.
  • the optional GKZ annealing it is preferred that the steel is annealed for 6-10 hours, preferably 7-9 hours, for example 8 hours, at a holding temperature of 700-750 °C, for example 735 °C.
  • cooling is preferably carried out to below 100 °C, particularly preferably below 50 °C, in particular to room temperature.
  • Annealing (heating) advantageously produces a microstructure of ferrite and spheroidal cementite.
  • a tempering step in which the known tempering processes for steels are suitable.
  • a tempering step may preferably also take place during and/or simultaneously with the heat treatment step.
  • the tempering and heating can take place together in a single step.
  • the optional heat treatment and/or tempering in step g) is preferably salt bath tempering, particularly preferably at a temperature of 200-450°C for 10 minutes to 3 hours.
  • the structure of the steel component after rolling in step b), in particular thermomechanical rolling, and before heat treatment in step f) is predominantly ferritic-pearlitic, bainitic, and/or a mixed structure.
  • the structure of the steel is ⁇ 80 vol.%, particularly preferably ⁇ 90 vol.% ferritic-pearlitic, bainitic, and/or a mixed structure.
  • the structure of the component in a preferred embodiment is predominantly martensitic and/or bainitic, as described above.
  • the microstructure of the steel component in the component according to the invention is ⁇ 70 vol.%, more preferably ⁇ 80 vol.%, particularly preferably ⁇ 90 vol.% bainitic or martensitic, as described above.
  • the microstructure of the steel in the edge region in particular the region from the surface of the steel component to a depth of 15 ⁇ m, preferably up to 12 ⁇ m, particularly preferably up to 10 ⁇ m, measured perpendicular to the surface of the steel component, is predominantly ferritic and/or pearlitic, preferably ⁇ 80 vol.%, particularly preferably ⁇ 90 vol.% ferritic and/or pearlitic.
  • the steel below the above-mentioned depths ie below a depth of 15 ⁇ m, preferably below a depth of 12 ⁇ m, particularly preferably below a depth of 10 ⁇ m, preferably has the structure described above, ie preferably ⁇ 70 vol.%, more preferably ⁇ 80 vol.%, particularly preferably ⁇ 90 vol.% bainitic or martensitic.
  • the steel component in the edge region in particular at a depth of 30-100 ⁇ m, preferably 50-150 ⁇ m, measured from the surface perpendicular to the surface of the steel component, has a Vickers hardness of ⁇ 350 HV 0.3, more preferably ⁇ 400 HV 0.3, particularly preferably ⁇ 430 HV 0.3, in particular ⁇ 450 HV 0.3.
  • the steel component has a Vickers hardness at a depth of 30-100 ⁇ m, preferably 40-120 ⁇ m, particularly preferably 50-150 ⁇ m, measured from the surface perpendicular to the surface of the steel component, that is less than 150 HV 0.3 below the Vickers hardness HV 0.3 of the steel component at a depth of 300-400 ⁇ m, in particular at a depth of 400 ⁇ m, particularly preferably at a depth of 1/4 of the diameter of the steel component.
  • the steel component has a depth of 30 - 100 ⁇ m, preferably 40 - 120 ⁇ m, particularly preferably 50 - 150 ⁇ m, measured from the surface perpendicular to the surface of the steel component, a Vickers hardness which is less than 100 HV 0.5, more preferably less than 60 HV 0.5, in particular less than 30 HV 0.5, below the Vickers hardness HV 0.5 of the steel component at a depth of 300 - 400 ⁇ m, also measured from the surface into the depth of the steel component, perpendicular to the surface of the steel component, in particular at a depth of 400 ⁇ m, particularly preferably at a depth of 1 ⁇ 4 of the diameter of the steel component.
  • the invention also relates to a component with a steel component, obtainable by the method according to the invention.
  • the component and/or the steel component can also have the aforementioned features with regard to the method.
  • Fig. 1 The hardness of the steel depends on the edge distance, measured perpendicular to the surface, of a screw according to the invention and it can be seen that there is only a slight decrease in hardness.
  • Fig. 2 The hardness profile of the steel in the edge region of a bainitic heat-treated B-alloy screw is shown, using a conventional B-alloy steel. It can be seen that there is a significant hardness drop in the edge region, combined with a greater depth of hardness drop, measured perpendicular to the surface of the screw.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Claims (15)

  1. Pièce ayant une composante d'acier,
    caractérisée en ce que l'acier contient
    0,30 à 0,50 % en poids de C,
    0,05 à 1,3 % en poids de Mn,
    0,001 à 0,015 % en poids de P,
    0,001 à 0,015 % en poids de S,
    0,01 à 0,8 % en poids de Si,
    0,3 à 1,5 % en poids de Cr,
    0,005 à 0,40 % en poids de V,
    0,0008 à 0,0050 % en poids de B,
    0,02 à 0,35 % en poids de AI,
    0,0001 à 0,0200 % en poids de N,
    0,01 à 0,08 % en poids de Ti, et
    0,0030 à 0,0800 % en poids de Zr ;
    optionnellement
    0,01 à 0,20 % en poids de Mo,
    0,01 à 0,50 % en poids de Ni,
    0,01 à 0,50 % en poids de Cu,
    0,0010 à 0,0100 % en poids de Ca,
    0,01 à 0,10 % en poids de Bi,
    0,01 à 0,30 % en poids de Co,
    0,01 à 0,06 % en poids de Nb,
    0,01 à 0,40 % en poids de Pb,
    0,01 à 0,10 % en poids de Se,
    0,01 à 0,10 % en poids de Te,
    0,01 à 0,3 % en poids de W,
    0,01 à 0,04 % en poids de As,
    0,01 à 0,20 % en poids de Ta,
    0,01 à 0,20 % en poids de Ce,
    0,01 à 0,50 % en poids de Sn,
    0,01 à 0,40 % en poids de Sb,
    0,01 à 0,20 % en poids de Hf, et/ou
    un ou plusieurs lanthanides, chacun en une quantité de 0,01 à 0,02 % en poids ;
    le reste étant du fer et des impuretés inévitables,
    chaque impureté inévitable représentant ≤ 0,01 % en poids, la composante de la pièce présentant une surface d'acier, et la teneur en B dans l'acier à une profondeur de 5 à 60 µm étant ≥ 80 % de la teneur en B dans l'acier à une profondeur de 500 µm, la profondeur étant mesurée perpendiculairement à la surface de l'acier.
  2. Pièce selon la revendication 1,
    caractérisée en ce que la teneur en B dans l'acier à une profondeur de 5 à 60 µm est ≥ 90 %, de préférence ≥ 95 %, de la teneur en B dans l'acier à une profondeur de 500 µm.
  3. Pièce selon la revendication 1 ou 2,
    caractérisée en ce que la teneur en B dans l'acier à une profondeur de 140 à 220 µm est ≥ 80 % de la teneur en B dans l'acier à une profondeur de 500 µm, la profondeur étant mesurée perpendiculairement à la surface de l'acier.
  4. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que la teneur en B dans l'acier à une profondeur de 140 à 220 µm est ≥ 90 %, de préférence ≥ 95 %, de la teneur en B de l'acier à une profondeur de 500 µm.
  5. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que l'acier est constitué des composantes indiquées.
  6. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que l'acier contient, de préférence est constitué de
    0,30 à 0,46 % en poids de C,
    0,3 à 1,3 % en poids de Mn,
    0,001 à 0,015 % en poids de P,
    0,001 à 0,015 % en poids de S,
    0,01 à 0,60 % en poids de Si,
    0,3 à 1,3 % en poids de Cr,
    0,005 à 0,35 % en poids de V,
    0,0012 à 0,0050 % en poids de B,
    0,02 à 0,25 % en poids de AI,
    0,0020 à 0,0150 % en poids de N,
    0,014 à 0,060 % en poids de Ti, et
    0,0050 à 0,0500 % en poids de Zr ;
    optionnellement
    0,01 à 0,16 % en poids de Mo,
    0,01 à 0,40 % en poids de Ni,
    0,01 à 0,30 % en poids de Cu, et/ou
    0,0010 à 0,0080 % en poids de Ca ;
    le reste étant du fer et des impuretés inévitables.
  7. Pièce selon l'une des revendications 1 à 5,
    caractérisée en ce que l'acier est constitué de
    0,30 à 0,50 % en poids de C,
    0,05 à 1,3 % en poids de Mn,
    0,001 à 0,015 % en poids de P,
    0,001 à 0,015 % en poids de S,
    0,01 à 0,8 % en poids de Si,
    0,3 à 1,5 % en poids de Cr,
    0,005 à 0,40 % en poids de V,
    0,0008 à 0,0050 % en poids de B,
    0,02 à 0,35 % en poids de AI,
    0,0001 à 0,0200 % en poids de N,
    0,01 à 0,08 % en poids de Ti, et
    0,0030 à 0,0800 % en poids de Zr ;
    optionnellement
    0,01 à 0,20 % en poids de Mo,
    0,01 à 0,50 % en poids de Ni,
    0,01 à 0,50 % en poids de Cu,
    0,0010 à 0,0100 % en poids de Ca,
    0,01 à 0,10 % en poids de Bi,
    0,01 à 0,30 % en poids de Co,
    0,01 à 0,06 % en poids de Nb,
    0,01 à 0,40 % en poids de Pb,
    0,01 à 0,10 % en poids de Se,
    0,01 à 0,10 % en poids de Te,
    0,01 à 0,3 % en poids de W,
    0,01 à 0,04 % en poids de As,
    0,01 à 0,20 % en poids de Ta,
    0,01 à 0,20 % en poids de Ce,
    0,01 à 0,50 % en poids de Sn,
    0,01 à 0,40 % en poids de Sb,
    0,01 à 0,20 % en poids de Hf, et/ou
    un ou plusieurs lanthanides, chacun en une quantité de 0,01 à 0,02 % en poids ;
    le reste étant du fer et des impuretés inévitables,
    chaque impureté inévitable représentant ≤ 0,01 % en poids.
  8. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que (Zr + Ti + Al) / N est compris dans une plage de 2,7 à 150, de préférence de 3 à 100.
  9. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que, à une profondeur de 30 à 100 µm, de préférence de 40 à 120 µm, de manière particulièrement préférée de 50 à 150 µm, mesurée à partir de la surface perpendiculairement à la surface de la composante d'acier, la composante d'acier présente une dureté Vickers qui est en dessous de la dureté Vickers HV 0,3 de la composante d'acier à une profondeur de 400 µm, et ceci d'une valeur inférieure à 150 HV 0,3, de préférence inférieure à 100 HV 0,3, de manière particulièrement préférée inférieure à 60 HV 0,3, en particulier inférieure à 30 HV 0,3.
  10. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que la pièce est un moyen de fixation, de préférence choisi dans le groupe constitué par les vis, les écrous, les rivets, les boulons et les chaînes.
  11. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que l'acier représente au moins 90 % en poids de la pièce et/ou en ce que la pièce présente une résistance à la traction selon la norme ISO 898-1:2021 de ≥ 800 MPa, de préférence de ≥ 1400 MPa.
  12. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que la structure de l'acier après un traitement de trempe et de revenu est à ≥ 90 % en volume bainitique et/ou martensitique.
  13. Pièce selon l'une des revendications précédentes,
    caractérisée en ce que la structure de l'acier sans traitement de trempe et revenu est à ≥ 90 % en volume ferritique-perlitique.
  14. Procédé de fabrication d'une pièce selon l'une des revendications précédentes,
    comprenant les étapes consistant à :
    - fournir un acier ayant une composition selon l'une des revendications 1 à 3,
    - mettre en forme une pièce ayant une composante dudit acier, et
    - optionnellement, la traiter thermiquement.
  15. Procédé selon la revendication 14,
    caractérisé en ce que le procédé comprend les étapes consistant à :
    a) fournir un acier ayant une composition selon l'une des revendications 1 à 8,
    b) laminer, en particulier laminer par voie thermomécanique, l'acier,
    c) fabriquer un fil ou un barreau dudit acier,
    d) optionnellement, le chauffer à une température de 700 à 750 °C pendant 6 à 10 heures,
    e) le tréfiler,
    f) le mettre en forme et
    g) optionnellement, le traiter thermiquement et/ou par trempe et revenu, en particulier par trempe et revenu en bain de sel.
EP22826100.4A 2021-12-02 2022-12-01 Composant en acier allié b-zr Active EP4247993B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP21211997.8A EP4190934A1 (fr) 2021-12-02 2021-12-02 Composant en acier allié b-zr
PCT/EP2022/084020 WO2023099654A1 (fr) 2021-12-02 2022-12-01 Élément en acier allié à base de b-zr

Publications (2)

Publication Number Publication Date
EP4247993A1 EP4247993A1 (fr) 2023-09-27
EP4247993B1 true EP4247993B1 (fr) 2025-07-30

Family

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EP22826100.4A Active EP4247993B1 (fr) 2021-12-02 2022-12-01 Composant en acier allié b-zr

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US (1) US20250019811A1 (fr)
EP (2) EP4190934A1 (fr)
KR (1) KR20240089753A (fr)
CN (1) CN118339322A (fr)
CA (1) CA3238223A1 (fr)
ES (1) ES3047366T3 (fr)
MX (1) MX2024006328A (fr)
WO (1) WO2023099654A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2914929B1 (fr) 2007-04-12 2010-10-29 Mittal Steel Gandrange Acier a bonne tenue a l'hydrogene pour le formage de pieces mecaniques a tres hautes caracteristiques.
WO2011040587A1 (fr) * 2009-10-02 2011-04-07 株式会社神戸製鋼所 Acier pour construction de machines et son procédé de fabrication, composants en acier cémenté et leur procédé de fabrication
JP5135557B2 (ja) * 2010-03-11 2013-02-06 新日鐵住金株式会社 耐遅れ破壊特性に優れた高強度鋼材と高強度ボルト、及び、その製造方法
JP6031022B2 (ja) * 2013-12-02 2016-11-24 株式会社神戸製鋼所 耐遅れ破壊性に優れたボルト用鋼線および高強度ボルト並びにそれらの製造方法
WO2021009543A1 (fr) 2019-07-16 2021-01-21 Arcelormittal Procédé de production de pièce en acier et pièce en acier

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Publication number Publication date
CA3238223A1 (fr) 2023-06-08
ES3047366T3 (en) 2025-12-03
KR20240089753A (ko) 2024-06-20
MX2024006328A (es) 2024-11-08
EP4190934A1 (fr) 2023-06-07
US20250019811A1 (en) 2025-01-16
CN118339322A (zh) 2024-07-12
EP4247993A1 (fr) 2023-09-27
WO2023099654A1 (fr) 2023-06-08

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