WO2017185320A1 - Low density zinc-coated steel produced by austenitizing and quench process - Google Patents

Low density zinc-coated steel produced by austenitizing and quench process Download PDF

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Publication number
WO2017185320A1
WO2017185320A1 PCT/CN2016/080626 CN2016080626W WO2017185320A1 WO 2017185320 A1 WO2017185320 A1 WO 2017185320A1 CN 2016080626 W CN2016080626 W CN 2016080626W WO 2017185320 A1 WO2017185320 A1 WO 2017185320A1
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steel alloy
vol
zinc coated
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PCT/CN2016/080626
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French (fr)
Inventor
Xiaochuan XIONG
Hongliang Yi
Jianfeng Wang
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GM Global Technology Operations LLC
Northeastern University
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Priority to PCT/CN2016/080626 priority Critical patent/WO2017185320A1/en
Publication of WO2017185320A1 publication Critical patent/WO2017185320A1/en

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    • 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
    • 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
    • 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
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon

Definitions

  • the present disclosure relates to methods of producing low density zinc coated steel alloys by austenitizing and quenching processes, while eliminating conventional partitioning processes.
  • Producing zinc coated steel alloys by quenching and partitioning processes are recently known processes used for automotive body structural applications, having tensile strength properties on the order of about 1000 megapascals (MPa) .
  • MPa megapascals
  • Such processes are typically accomplished according to the following steps.
  • a steel alloy is austenitized in an austenitizing furnace. The temperature depends on the composition of the steel alloy, but typical austenizing temperatures range from greater than or equal to about 760°C up to about 900°C and the steel alloy may be held in the furnace for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes.
  • the austenitized steel alloy is then quenched to a temperature of greater than or equal to about 200°C to less than or equal to about 250°C.
  • the quenched steel alloy is introduced into a partitioner and partitioned at about 350°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes.
  • the austenitized steel alloy is galvanized in a galvanizing bath at a temperature of about 460°C.
  • the zinc coated steel alloy is cooled to room temperature or heated to a temperature of from greater than or equal to about 500°C to less than or equal to about 565°C for a period of less than or equal to about 10 seconds.
  • Conventional steel alloys for producing such a zinc coated steel alloy may, as one non-limiting example, have a composition of less than or equal to about 0.3 wt. %C; less than or equal to about 2 wt. %Si; less than or equal to about 2 wt. %Mn; less than or equal to about 9 wt. %Cr; less than or equal to about 25 wt. %Ni; less than or equal to about 4.1 wt. %Mo; and a balance of iron and impurities.
  • the present disclosure provides a method of producing a zinc coated steel alloy.
  • the zinc coated steel alloy has a composition comprising carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt. %; and a balance of iron and impurities.
  • a steel alloy is first austenitized.
  • the austenitized steel alloy is then quenched to a temperature of from greater than or equal to about 25°C to less than or equal to about 100°C.
  • the quenched steel alloy is galvanized to form a zinc coated steel alloy.
  • the zinc coated steel alloy is cooled to room temperature.
  • the zinc coated steel alloy may have a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol. %to less than or equal to about 40 vol. %martensite; and greater than or equal to about 10 vol. %to less than or equal to about 20 vol. %metastable retained austenite.
  • the austenitizing may be done in an austenitizing furnace at a temperature of greater than or equal to about 800°C to less than or equal to about 900°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes.
  • the quenched steel alloy may be heated prior to galvanizing.
  • the quenched steel alloy may be galvannealed after galvanizing the steel alloy.
  • the quenching may occur at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second.
  • the quenching may occur in a bath, such as a water bath or oil bath.
  • the zinc coated steel alloy may have a tensile strength of greater than or equal to about 1000 MPa.
  • the present disclosure provides a method of producing a zinc coated steel alloy.
  • the zinc coated steel alloy has a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol. %to less than or equal to about 40 vol. %martensite; and greater than or equal to about 10 vol. %to less than or equal to about 20 vol. %metastable retained austenite.
  • a steel alloy is first austenitized. The austenitized steel alloy is then quenched to a temperature of from greater than or equal to about 25°C to less than or equal to about 100°C.
  • the austenitized steel alloy is galvanized to form a zinc coated steel alloy. Finally, the zinc coated steel alloy is cooled to room temperature.
  • the zinc coated steel alloy may have a composition comprising carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt. %; and a balance of iron and impurities.
  • the austenitizing may be done in an austenitizing furnace at a temperature of greater than or equal to about 800°C to less than or equal to about 900°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes.
  • the quenched steel alloy may be heated prior to galvanizing.
  • the zinc coated steel alloy may be galvannealed after galvanizing the steel alloy.
  • the quenching may occur at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second.
  • the quenching may occur in a bath, such as a water bath or oil bath.
  • the zinc coated steel alloy may have a tensile strength of greater than or equal to about 1000 MPa.
  • the zinc coated steel alloy may have a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol. %to less than or equal to about 40 vol. %martensite; and greater than or equal to about 10 vol. %to less than or equal to about 20 vol. %metastable retained austenite.
  • the present disclosure provides a method of producing a zinc coated steel alloy.
  • the zinc coated steel alloy has a tensile strength of greater than or equal to about 1000 MPa.
  • a steel alloy is first austenitized.
  • the austenitized steel alloy is then quenched to a temperature of from greater than or equal to about 25°C to less than or equal to about 100°C.
  • the quenched steel alloy is galvanized to form a zinc coated steel alloy.
  • the zinc coated steel alloy is cooled to room temperature.
  • the zinc coated steel alloy may have a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol.
  • the zinc coated steel alloy may have a composition comprising carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt.
  • the austenitizing may be done in an austenitizing furnace at a temperature of greater than or equal to about 800°C to less than or equal to about 900°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes.
  • the quenched steel alloy may be heated prior to galvanizing.
  • the zinc coated steel alloy may be galvannealed after galvanizing the steel alloy.
  • the quenching may occur at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second.
  • the quenching may occur in a bath, such as a water bath or oil bath.
  • the method consists essentially of austenitizing a steel alloy and quenching the austenitized steel alloy, followed by simultaneously galvanizing and partitioning the quenched steel alloy and cooling the zinc coated steel alloy.
  • the method consists of austenitizing a steel alloy and quenching the austenitized steel alloy, followed by simultaneously galvanizing and partitioning the quenched steel alloy and cooling the zinc coated steel alloy.
  • FIG. 1 shows a representative automotive A-pillar manufactured according to an aspect of the present disclosure.
  • FIG. 2 shows a process for producing a zinc coated steel alloy using a conventional steel alloy according to a conventional quench and partition process.
  • FIG. 3 shows an exemplary process for producing a zinc coated steel alloy in accordance with certain aspects of the present disclosure.
  • FIG. 4 is a schematic chart comparing the temperatures of conventional quench and partition processes to the processes according to certain aspects of the present disclosure.
  • Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
  • first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and/or sections, these steps, elements, components, regions, layers and/or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as “first, “ “second, “ and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.
  • composition refers broadly to a substance containing at least the preferred metal elements or compounds, but which optionally comprises additional substances or compounds, including additives and impurities.
  • material also broadly refers to matter containing the preferred compounds or composition.
  • disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges.
  • High-strength, lightweight alloy components are particularly suitable for use in components of an automobile or other vehicle (e.g., motorcycles, boats) , but may also be used in a variety of other industries and applications, including aerospace components, industrial equipment and machinery, farm equipment, heavy machinery, by way of non-limiting example. While not limiting, the present methods and materials are particularly suitable for forming lightweight, high-strength components for a vehicle, including automotive structural components such as A-pillars.
  • an exemplary automotive structural component such as A-pillar 10
  • the zinc coating steel alloy is formed from austenitizing, quenching, and zinc coating a steel alloy.
  • the process excludes the partitioning step of conventional quench and partition processes (e.g., holding at a temperature of about 350°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes) . Rather, partitioning occurs according to the present disclosure simultaneously with galvanizing.
  • the steel alloy may be galvannealed after galvanizing the steel alloy.
  • inventive concepts in the present disclosure may also be applied to any structural component capable of being formed from austenitization, quenching, and zinc coating a steel alloy, including those used in vehicles, like automotive applications including, but not limited to, pillars, such as hinge pillars, panels, including structural panels, door panels, and door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, including glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets and other components, shock tower cap, control arms and other suspension, undercarriage or drive train components, and the like.
  • the present disclosure is particularly suitable for any piece of hardware subject to loads or impact (e.g., load bearing) or requiring cathodic protection.
  • Suitable steel compositions may comprise carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt. %; and a balance of iron and impurities.
  • a steel alloy is introduced into an austenitizing furnace 102 and heated to a temperature of from greater than or equal to about 760°C to less than or equal to about 860°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes to austenitize the steel alloy.
  • the steel alloy is quenched in a quencher 104 so that is reaches a temperature of greater than or equal to about 200°C to less than or equal to about 250°C.
  • the steel alloy must be quenched at a rate of greater than or equal to about 20°C per second to prevent bainitic formation and below a martensitic transformation start temperature such that austenite transforms to martensite.
  • the steel alloy is heated in furnace 106 to a temperature of about 350°C.
  • the steel alloy is then partitioned in partitioner 108 at a temperature of about 350°C for several minutes. Partitioning the quenched steel alloy enriches the remaining austenite with carbon.
  • the partitioned steel alloy is heated in yet another furnace 110 to a temperature of greater than or equal to about 460°C to less than or equal to about 490°C.
  • the steel alloy is galvanized in a galvanizer 112.
  • the zinc coated alloy is galvannealed (not shown) .
  • the zinc coated steel alloy is cooled in a cooling device 114 to a temperature below the temperature at which martensitic formation finishes.
  • Conventional steel alloys for producing such a zinc coated steel alloy may, as one non-limiting example, have a composition of less than or equal to about 0.3 wt. %C; less than or equal to about 2 wt. %Si; less than or equal to about 2 wt. %Mn; less than or equal to about 9 wt. %Cr; less than or equal to about 25 wt. %Ni; less than or equal to about 4.1 wt. %Mo; and a balance of iron and impurities.
  • the zinc coated steel alloy may have a multiphase microstructure comprising from greater than or equal to about 30 vol. %to less than or equal to about 40 vol. %ferrite; from greater than or equal to about 10 vol.
  • the zinc coated steel alloy may have an elongation of about 20%as a non-limiting example.
  • the methods of producing a zinc coated steel alloy contemplated provide the ability to eliminate the partitioning step. Further still, the methods of producing a zinc coated steel alloy contemplated herein provide the ability to quench the austenitized steel alloy at a temperature much lower than those according to conventional quench and partition processes. Achieving this conventional quench temperature range at the required cooling rates in particular poses significant technical challenges in practice. Thus, the overall process according to the present disclosure desirably reduces processing time, energy requirements, and cost. Furthermore, the zinc coated steel alloy has high ductility and is lighter than a zinc coated steel alloy made according to a conventional quench and partition process.
  • a steel alloy is introduced into an austenitizing furnace 202 and heated to a temperature of from greater than or equal to about 800°C to less than or equal to about 900 °C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes to austenitize the steel alloy.
  • the steel alloy is quenched in a quencher 204 to a temperature of greater than or equal to about 25°C to less than or equal to about 100°C.
  • the steel alloy must be quenched at a rate of greater than or equal to about 20°C per second to prevent bainitic formation and below a martensitic transformation temperature to transform austenite to martensite. More particularly, the quenching may occur at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second.
  • the steel alloy is quenched to a temperature below the temperature at which martensite formation begins and more particularly to a temperature of from greater than or equal to about 25°C to less than or equal to about 100 °C. This quenching temperature range is significantly lower than the conventional quenching temperature range (e.g., 200–250°C) .
  • the steel compositions disclosed herein are believed to account for the differences in the martensite formation and martensite finishing temperatures achieved according to the present disclosure.
  • the steel alloy is heated in furnace 206 to a temperature of greater than or equal to about 460°C to less than or equal to about 490°C.
  • the steel alloy is then galvanized in a galvanizer 208. Galvanizing the steel alloy in galvanizer 208 both galvanizes the steel alloy and enriches the remaining austenite with carbon.
  • the zinc coated steel alloy is then galvannealed by heating in furnace 210 the zinc coated steel alloy to a temperature of from greater than or equal to about 500°C to less than or equal to about 565°C for a period of less than or equal to about 10 seconds.
  • the zinc coated steel alloy is cooled in a cooling device 212 to room temperature.
  • the process according to various aspects of the present disclosure excludes the partitioning step present in a conventional process (e.g., holding at a temperature of about 350°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes) .
  • suitable steel compositions for the process described above may comprise carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt. %; and a balance of iron and impurities.
  • Martensite transformation begins as the austenitized steel alloy is quenched below a martensitic phase transformation starting temperature.
  • quench and partition processes using conventional steel alloys require the quenching to be held at a temperature of from greater than or equal to about 200°C to less than or equal to about 250°C to ensure adequate martensitic transformation. Quenching to such temperatures is not cost efficient and may, for example, require high capital expenditures to obtain suitable equipment for quenching to such temperatures.
  • the quench process using the steel alloy according to the present disclosure is not so limited and the quenching may be done, for example, in a bath, such as a water bath or oil bath.
  • the addition of aluminum enables elimination of conventional partitioning steps altogether (e.g., holding at a temperature of about 350°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes) .
  • quench and partition processes using conventional steel alloys require partitioning to transfer carbon from the martensite to the retained austenite.
  • the addition of aluminum enables the carbon to transfer rapidly and sufficiently such that the transfer of carbon is accomplished while the steel alloy is being galvanized. Therefore, a distinct partition process step is not required according to the present disclosure. The process according to the present disclosure therefore results in cost, energy, and time savings.
  • a distinct partitioning step may yet occur at a temperature below the martensite formation temperature. Such embodiments might not offer the consolidation of galvanization and partitioning as disclosed by other, preferred embodiments. According to yet certain other embodiments, a distinct partitioning step may yet occur at a temperature above the martensite formation temperature. Such embodiments might not offer the consolidation of galvanization and partitioning as disclosed by other, preferred embodiments. According to still yet certain other embodiments, the rapid and sufficient transfer of carbon may be accomplished while the quenched steel alloy is heated to a temperature of greater than or equal to about 460°C to less than or equal to about 490°C.
  • FIG. 4 which shows on the x-axis time 300 and on the y-axis 302 temperature
  • the process according to the present disclosure as a function of temperature and time is plotted as 304.
  • a conventional steel alloy undergoing a quench and partition process as a function of temperature and time is plotted as 306.
  • plot 306 has multiple plateaus, which, moving from left to right, relate to the higher quench temperature and the partitioning, respectively.
  • the process according to the present disclosure requires allows for a quenching at a lower temperature and omits partitioning altogether.
  • the zinc coated steel alloy according to the present disclosure yet may result in a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol. %to less than or equal to about 40 vol. %martensite; and greater than or equal to about 10 vol. %to less than or equal to about 20 vol. %metastable retained austenite, even without the higher quench temperature and partitioning required by steel alloys used in conventional quench and partition processes.
  • the zinc coated steel alloy according to the present disclosure provides excellent strength. More specifically, the zinc coated steel alloy according to the present disclosure may have an ultimate tensile strength of greater than or equal to about 1000 MPa. Further, the zinc coated steel alloy according to the present disclosure provides good elongation. More specifically, the zinc coated steel alloy according to the present disclosure may have an elongation of greater than or equal to about 25%.
  • the zinc coated steel alloy according to the present disclosure is lightweight. More specifically, the zinc coated steel alloy material having compositions according to the present disclosure may be on average from greater than or equal to about 3%to less than or equal to about 6%lighter than the steel alloys described above used in conventional quench and partition processes and may have a density of from greater than or equal to about 7.3 g/cm 3 to less than or equal to about 7.6 g/cm 3 . Moreover, as noted above, many metal parts can be made using the compositions according to the present disclosure to form vehicle components. Vehicles having metal parts made using the compositions according to the present disclosure therefore potentially translate to weight savings. Reducing the weight of components in part is important for improving efficiency and is of great importance for fuel efficiency in mobile applications, such as in automobiles.
  • a process may consist essentially of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800°C to less than or equal to about 900°C for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25°C to less than or equal to about 100°C. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy is comprised of carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt.
  • silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt. %; and a balance of iron and impurities.
  • the process may be further limited as further consisting essentially of any of, any combination of, or all of the following: (1) quenching in a bath; (2) quenching at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second; (3) heating the quenched steel alloy prior to galvanization; (4) having a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol. %to less than or equal to about 40 vol. %martensite; and greater than or equal to about 10 vol. %to less than or equal to about 20 vol.
  • the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy.
  • the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
  • a process may consist essentially of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800°C to less than or equal to about 900°C for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25°C to less than or equal to about 100°C. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled.
  • the zinc coated steel alloy has a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol.
  • the process may be further limited as further consisting essentially of any of, any combination of, or all of the following: (1) quenching in a bath; (2) quenching at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second; (3) heating the quenched steel alloy prior to galvanization; (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt.
  • the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy.
  • the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
  • a process may consist essentially of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800°C to less than or equal to about 900°C for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25°C to less than or equal to about 100°C. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa.
  • the process may be further limited as further consisting essentially of any of, any combination of, or all of the following: (1) quenching in a bath; (2) quenching at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second; (3) heating the quenched steel alloy prior to galvanization; (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt.
  • the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy.
  • the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
  • a process may consist of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800°C to less than or equal to about 900°C for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25 °C to less than or equal to about 100°C. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy is comprised of carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt.
  • silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt. %to less than or equal to about 5 wt. %; chromium at less than or equal to about 1 wt. %; and a balance of iron and impurities.
  • the process may be further limited as further consisting of any of, any combination of, or all of the following: (1) quenching in a bath; (2) quenching at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second; (3) heating the quenched steel alloy prior to galvanization; (4) having a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol. %to less than or equal to about 40 vol. %martensite; and greater than or equal to about 10 vol. %to less than or equal to about 20 vol.
  • the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the galvanized steel alloy.
  • the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
  • a process may consist of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800°C to less than or equal to about 900°C for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25 °C to less than or equal to about 100°C. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled.
  • the zinc coated steel alloy has a multiphase microstructure comprising greater than or equal to about 50 vol. %to less than or equal to about 65 vol. %ferrite; greater than or equal to about 15 vol.
  • the process may be further limited as further consisting of any of, any combination of, or all of the following: (1) quenching in a bath; (2) quenching at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second; (3) heating the quenched steel alloy prior to galvanization; (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt.
  • the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy.
  • the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
  • a process may consist of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800°C to less than or equal to about 900°C for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25 °C to less than or equal to about 100°C. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa.
  • the process may be further limited as further consisting of any of, any combination of, or all of the following: (1) quenching in a bath; (2) quenching at a rate of greater than or equal to about 20°C per second to less than or equal to about 30°C per second; (3) heating the quenched steel alloy prior to galvanization; (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. %to less than or equal to about 0.45 wt. %; silicon at less than or equal to about 0.5 wt. %; manganese at greater than or equal to about 0.5 wt. %to less than or equal to about 1.5 wt. %; aluminum at greater than or equal to about 3 wt.
  • the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy.
  • the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.

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Abstract

Methods for forming zinc coated steel alloys are provided via austenitizing and quenching. A conventional step of partitioning is eliminated and the zinc coated steel alloys may have an ultimate tensile strength of at least about 1000 MPa. The zinc coated steel alloy may have a multiphase microstructure at≥about 50 to≤about 65% ferrite; ≥about 15 to≤about 40% martensite; and≥about 10 to≤about 20% metastable retained austenite. The zinc coated steel alloy preferably comprises carbon at≥0.35 to≤about 0.45 wt. %; silicon at≤about 0.5; manganese at≥about 0.5 to≤about 1.5 wt. %; aluminum at≥about 3 to≤about 5 wt. %; chromium at≤about 1 wt. %; and a balance of iron and impurities.

Description

LOW DENSITY ZINC-COATED STEEL PRODUCED BY AUSTENITIZING AND QUENCH PROCESS FIELD
The present disclosure relates to methods of producing low density zinc coated steel alloys by austenitizing and quenching processes, while eliminating conventional partitioning processes.
BACKGROUND
This section provides background information related to the present disclosure which is not necessarily prior art.
Producing zinc coated steel alloys by quenching and partitioning processes are recently known processes used for automotive body structural applications, having tensile strength properties on the order of about 1000 megapascals (MPa) . Generally speaking, such processes are typically accomplished according to the following steps. First, a steel alloy is austenitized in an austenitizing furnace. The temperature depends on the composition of the steel alloy, but typical austenizing temperatures range from greater than or equal to about 760℃ up to about 900℃ and the steel alloy may be held in the furnace for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes. As one non-limiting example, the austenitized steel alloy is then quenched to a temperature of greater than or equal to about 200℃ to less than or equal to about 250℃. After quenching, as one non-limiting example, the quenched steel alloy is introduced into a partitioner and partitioned at about 350℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes. After partitioning, the austenitized steel alloy is galvanized in a galvanizing bath at a temperature of about 460℃. Finally, the zinc  coated steel alloy is cooled to room temperature or heated to a temperature of from greater than or equal to about 500℃ to less than or equal to about 565℃ for a period of less than or equal to about 10 seconds.
Conventional steel alloys for producing such a zinc coated steel alloy may, as one non-limiting example, have a composition of less than or equal to about 0.3 wt. ％C； less than or equal to about 2 wt. ％Si； less than or equal to about 2 wt. ％Mn； less than or equal to about 9 wt. ％Cr； less than or equal to about 25 wt. ％Ni； less than or equal to about 4.1 wt. ％Mo； and a balance of iron and impurities.
While steels produced by quenching and partitioning offer excellent strength for many applications, there is a continual need to improve upon the processes to reduce costs and the duration of the process associated therewith. There is a further need to reduce the mass of vehicle components for improved fuel efficiency without sacrificing requisite tensile strengths.
SUMMARY
This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
In various aspects, the present disclosure provides a method of producing a zinc coated steel alloy. The zinc coated steel alloy has a composition comprising carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities. To produce the zinc coated steel alloy, a steel alloy is  first austenitized. The austenitized steel alloy is then quenched to a temperature of from greater than or equal to about 25℃ to less than or equal to about 100℃. Next, the quenched steel alloy is galvanized to form a zinc coated steel alloy. Finally, the zinc coated steel alloy is cooled to room temperature. The zinc coated steel alloy may have a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite. The austenitizing may be done in an austenitizing furnace at a temperature of greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes. The quenched steel alloy may be heated prior to galvanizing. The quenched steel alloy may be galvannealed after galvanizing the steel alloy. The quenching may occur at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second. The quenching may occur in a bath, such as a water bath or oil bath. The zinc coated steel alloy may have a tensile strength of greater than or equal to about 1000 MPa.
In yet other aspects, the present disclosure provides a method of producing a zinc coated steel alloy. The zinc coated steel alloy has a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite. To produce the zinc coated steel alloy, a steel alloy is first austenitized. The austenitized steel alloy is then quenched to a temperature of from greater  than or equal to about 25℃ to less than or equal to about 100℃. Next, the austenitized steel alloy is galvanized to form a zinc coated steel alloy. Finally, the zinc coated steel alloy is cooled to room temperature. The zinc coated steel alloy may have a composition comprising carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities. The austenitizing may be done in an austenitizing furnace at a temperature of greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes. The quenched steel alloy may be heated prior to galvanizing. The zinc coated steel alloy may be galvannealed after galvanizing the steel alloy. The quenching may occur at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second. The quenching may occur in a bath, such as a water bath or oil bath. The zinc coated steel alloy may have a tensile strength of greater than or equal to about 1000 MPa. The zinc coated steel alloy may have a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite.
In still other embodiments, the present disclosure provides a method of producing a zinc coated steel alloy. The zinc coated steel alloy has a tensile strength of greater than or equal to about 1000 MPa. To produce the zinc coated steel alloy, a steel alloy is first  austenitized. The austenitized steel alloy is then quenched to a temperature of from greater than or equal to about 25℃ to less than or equal to about 100℃. Next, the quenched steel alloy is galvanized to form a zinc coated steel alloy. Finally, the zinc coated steel alloy is cooled to room temperature. The zinc coated steel alloy may have a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite. The zinc coated steel alloy may have a composition comprising carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities. The austenitizing may be done in an austenitizing furnace at a temperature of greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes. The quenched steel alloy may be heated prior to galvanizing. The zinc coated steel alloy may be galvannealed after galvanizing the steel alloy. The quenching may occur at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second. The quenching may occur in a bath, such as a water bath or oil bath.
In certain variations, the method consists essentially of austenitizing a steel alloy and quenching the austenitized steel alloy, followed by simultaneously  galvanizing and partitioning the quenched steel alloy and cooling the zinc coated steel alloy.
In yet other variations, the method consists of austenitizing a steel alloy and quenching the austenitized steel alloy, followed by simultaneously galvanizing and partitioning the quenched steel alloy and cooling the zinc coated steel alloy.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
DRAWINGS
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
FIG. 1 shows a representative automotive A-pillar manufactured according to an aspect of the present disclosure.
FIG. 2 shows a process for producing a zinc coated steel alloy using a conventional steel alloy according to a conventional quench and partition process.
FIG. 3 shows an exemplary process for producing a zinc coated steel alloy in accordance with certain aspects of the present disclosure.
FIG. 4 is a schematic chart comparing the temperatures of conventional quench and partition processes to the processes according to certain aspects of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
DETAILED DESCRIPTION
Example embodiments will now be described more fully with reference to the accompanying drawings.
Example embodiments are provided so that this disclosure will be thorough, and will fully convey the scope to those who are skilled in the art. Numerous specific details are set forth such as examples of specific compositions, components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that example embodiments may be embodied in many different forms and that neither should be construed to limit the scope of the disclosure. In some example embodiments, well-known processes, well-known device structures, and well-known technologies are not described in detail.
The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting. As used herein, the singular forms "a, " "an, " and "the" may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises, " "comprising, " "including, " and "having, " are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or  illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed, unless otherwise indicated.
When a component, element, or layer is referred to as being "on, " "engaged to, " "connected to, " or "coupled to" another element or layer, it may be directly on, engaged, connected or coupled to the other component, element, or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on, " "directly engaged to, " "directly connected to, " or "directly coupled to" another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., "between" versus "directly between, " "adjacent" versus "directly adjacent, " etc. ) . As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Although the terms first, second, third, etc. may be used herein to describe various steps, elements, components, regions, layers and/or sections, these steps, elements, components, regions, layers and/or sections should not be limited by these terms, unless otherwise indicated. These terms may be only used to distinguish one step, element, component, region, layer or section from another step, element, component, region, layer or section. Terms such as "first, " "second, " and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first step, element, component, region, layer or section discussed below could be termed a second step, element, component, region, layer or section without departing from the teachings of the example embodiments.
Spatially or temporally relative terms, such as "before, " "after, " "inner, " "outer, " "beneath, " "below, " "lower, " "above, " "upper, " and the like, may be used herein for ease of description to describe one element or feature's relationship to another element (s) or feature (s) as illustrated in the figures. Spatially or temporally relative terms may be intended to encompass different orientations of the device or system in use or operation in addition to the orientation depicted in the figures.
It should be understood for any recitation of a method, composition, device, or system that “comprises” certain steps, ingredients, or features, that in certain alternative variations, it is also contemplated that such a method, composition, device, or system may also "consist essentially of" or “consist of” the enumerated steps, ingredients, or features. In the case of “consisting of, ” the alternative embodiment excludes any additional steps, ingredients, or features, while in the case of “consisting essentially of, ” any additional steps, ingredients, or features that materially affect the basic and novel characteristics are excluded from such an embodiment, but any steps, ingredients, or features that do not materially affect the basic and novel characteristics can be included in the embodiment.
Throughout this disclosure, the numerical values represent approximate measures or limits to ranges to encompass minor deviations from the given values and embodiments having about the value mentioned as well as those having exactly the value mentioned. Other than in the working examples provided at the end of the detailed description, all numerical values of parameters (e.g., of quantities or conditions) in this specification, including the appended claims, are to be understood as being modified in all instances by the term "about" whether or not "about" actually appears before the numerical  value. "About" indicates that the stated numerical value allows some slight imprecision (with some approach to exactness in the value； approximately or reasonably close to the value； nearly) . Ifthe imprecision provided by"about" is not otherwise understood in the art with this ordinary meaning, then "about" as used herein indicates at least variations that may arise from ordinary methods of measuring and using such parameters. If, for some reason, the imprecision provided by “about” is not otherwise understood in the art with this ordinary meaning, then “about” as used herein may indicate a possible variation of up to 5％of the indicated value or 5％variance from usual methods of measurement.
As used herein, the term “composition” refers broadly to a substance containing at least the preferred metal elements or compounds, but which optionally comprises additional substances or compounds, including additives and impurities. The term “material” also broadly refers to matter containing the preferred compounds or composition.
In addition, disclosure of ranges includes disclosure of all values and further divided ranges within the entire range, including endpoints and sub-ranges given for the ranges.
The present disclosure provides methods of forming a lightweight, high-strength structural components. High-strength, lightweight alloy components are particularly suitable for use in components of an automobile or other vehicle (e.g., motorcycles, boats) , but may also be used in a variety of other industries and applications, including aerospace components, industrial equipment and machinery, farm equipment, heavy machinery, by way of non-limiting example. While not limiting, the present  methods and materials are particularly suitable for forming lightweight, high-strength components for a vehicle, including automotive structural components such as A-pillars.
Referring first to FIG. 1, an exemplary automotive structural component, such as A-pillar 10, is shown that can be produced from a zinc coated steel alloy prepared according to the present disclosure. In certain variations, the zinc coating steel alloy is formed from austenitizing, quenching, and zinc coating a steel alloy. Notably, the process excludes the partitioning step of conventional quench and partition processes (e.g., holding at a temperature of about 350℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes) . Rather, partitioning occurs according to the present disclosure simultaneously with galvanizing. In other aspects, the steel alloy may be galvannealed after galvanizing the steel alloy. It will be appreciated by those skilled in the art that numerous other components may be fabricated by the methods of the present invention, and that such additional components are deemed to be within the scope of the present invention. Thus, while exemplary components are illustrated and described throughout the specification, it is understood that the inventive concepts in the present disclosure may also be applied to any structural component capable of being formed from austenitization, quenching, and zinc coating a steel alloy, including those used in vehicles, like automotive applications including, but not limited to, pillars, such as hinge pillars, panels, including structural panels, door panels, and door components, interior floors, floor pans, roofs, exterior surfaces, underbody shields, wheels, storage areas, including glove boxes, console boxes, trunks, trunk floors, truck beds, lamp pockets and other components, shock tower cap, control arms and other suspension, undercarriage or drive train components, and the like. Specifically, the present disclosure is particularly suitable for  any piece of hardware subject to loads or impact (e.g., load bearing) or requiring cathodic protection.
Suitable steel compositions may comprise carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities.
Referring to FIG. 2, a flowchart showing the steps of a conventional quench and partition process 100 is shown. A steel alloy is introduced into an austenitizing furnace 102 and heated to a temperature of from greater than or equal to about 760℃ to less than or equal to about 860℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes to austenitize the steel alloy. After austenitization, the steel alloy is quenched in a quencher 104 so that is reaches a temperature of greater than or equal to about 200℃ to less than or equal to about 250℃. At a minimum, the steel alloy must be quenched at a rate of greater than or equal to about 20℃ per second to prevent bainitic formation and below a martensitic transformation start temperature such that austenite transforms to martensite. After quenching, the steel alloy is heated in furnace 106 to a temperature of about 350℃. The steel alloy is then partitioned in partitioner 108 at a temperature of about 350℃ for several minutes. Partitioning the quenched steel alloy enriches the remaining austenite with carbon. Next, the partitioned steel alloy is heated in yet another furnace 110 to a temperature of greater than or equal to about 460℃ to less than or equal to about 490℃. The steel alloy is galvanized in a galvanizer 112. Optionally, the zinc coated alloy is galvannealed (not shown) . Finally, the zinc coated steel alloy is cooled in a cooling device 114 to a temperature below the temperature at which martensitic formation finishes.
Conventional steel alloys for producing such a zinc coated steel alloy may, as one non-limiting example, have a composition of less than or equal to about 0.3 wt. ％C； less than or equal to about 2 wt. ％Si； less than or equal to about 2 wt. ％Mn； less than or equal to about 9 wt. ％Cr； less than or equal to about 25 wt. ％Ni； less than or equal to about 4.1 wt. ％Mo； and a balance of iron and impurities. The zinc coated steel alloy may have a multiphase microstructure comprising from greater than or equal to about 30 vol. ％to less than or equal to about 40 vol. ％ferrite； from greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite； and from greater than or equal to about 40 vol. ％to less than or equal to about 60 vol. ％martensite. The zinc coated steel alloy may have an elongation of about 20％as a non-limiting example.
In accordance with certain aspects of the present disclosure, the methods of producing a zinc coated steel alloy contemplated provide the ability to eliminate the partitioning step. Further still, the methods of producing a zinc coated steel alloy contemplated herein provide the ability to quench the austenitized steel alloy at a temperature much lower than those according to conventional quench and partition processes. Achieving this conventional quench temperature range at the required cooling rates in particular poses significant technical challenges in practice. Thus, the overall process according to the present disclosure desirably reduces processing time, energy requirements, and cost. Furthermore, the zinc coated steel alloy has high ductility and is  lighter than a zinc coated steel alloy made according to a conventional quench and partition process.
Referring to FIG. 3, a flowchart showing the steps of the austenitizing, quench, and zinc coating process 200 in accordance with certain aspects of the present disclosure. A steel alloy is introduced into an austenitizing furnace 202 and heated to a temperature of from greater than or equal to about 800℃ to less than or equal to about 900 ℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes to austenitize the steel alloy. After austenitization, the steel alloy is quenched in a quencher 204 to a temperature of greater than or equal to about 25℃ to less than or equal to about 100℃. At a minimum, the steel alloy must be quenched at a rate of greater than or equal to about 20℃ per second to prevent bainitic formation and below a martensitic transformation temperature to transform austenite to martensite. More particularly, the quenching may occur at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second. The steel alloy is quenched to a temperature below the temperature at which martensite formation begins and more particularly to a temperature of from greater than or equal to about 25℃ to less than or equal to about 100 ℃. This quenching temperature range is significantly lower than the conventional quenching temperature range (e.g., 200–250℃) . The steel compositions disclosed herein are believed to account for the differences in the martensite formation and martensite finishing temperatures achieved according to the present disclosure.
After quenching, the steel alloy is heated in furnace 206 to a temperature of greater than or equal to about 460℃ to less than or equal to about 490℃. The steel alloy is then galvanized in a galvanizer 208. Galvanizing the steel alloy in galvanizer 208  both galvanizes the steel alloy and enriches the remaining austenite with carbon. Optionally, the zinc coated steel alloy is then galvannealed by heating in furnace 210 the zinc coated steel alloy to a temperature of from greater than or equal to about 500℃ to less than or equal to about 565℃ for a period of less than or equal to about 10 seconds. Finally, the zinc coated steel alloy is cooled in a cooling device 212 to room temperature. Notably, the process according to various aspects of the present disclosure excludes the partitioning step present in a conventional process (e.g., holding at a temperature of about 350℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes) .
As noted above, suitable steel compositions for the process described above may comprise carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities.
It is believed that the addition of aluminum offers several heretofore unrecognized benefits. Martensite transformation begins as the austenitized steel alloy is quenched below a martensitic phase transformation starting temperature. As one non-limiting example, quench and partition processes using conventional steel alloys require the quenching to be held at a temperature of from greater than or equal to about 200℃ to less than or equal to about 250℃ to ensure adequate martensitic transformation. Quenching to such temperatures is not cost efficient and may, for example, require high capital expenditures to obtain suitable equipment for quenching to such temperatures. The quench  process using the steel alloy according to the present disclosure, however, is not so limited and the quenching may be done, for example, in a bath, such as a water bath or oil bath. Indeed, while not wishing to be bound to theory, it is believed that the addition of aluminum assists in lowering either or both of the martensitic transformation and martensitic finishing temperatures such that martensitic transformation of steel compositions according to the present disclosure occurs at a temperature of greater than or equal to about 25℃ to less than or equal to about 100℃.
Further still, it is believed that the addition of aluminum enables elimination of conventional partitioning steps altogether (e.g., holding at a temperature of about 350℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes) . More specifically, quench and partition processes using conventional steel alloys require partitioning to transfer carbon from the martensite to the retained austenite. The addition of aluminum, however, enables the carbon to transfer rapidly and sufficiently such that the transfer of carbon is accomplished while the steel alloy is being galvanized. Therefore, a distinct partition process step is not required according to the present disclosure. The process according to the present disclosure therefore results in cost, energy, and time savings.
According to certain other embodiments, a distinct partitioning step may yet occur at a temperature below the martensite formation temperature. Such embodiments might not offer the consolidation of galvanization and partitioning as disclosed by other, preferred embodiments. According to yet certain other embodiments, a distinct partitioning step may yet occur at a temperature above the martensite formation temperature. Such embodiments might not offer the consolidation of galvanization and partitioning as  disclosed by other, preferred embodiments. According to still yet certain other embodiments, the rapid and sufficient transfer of carbon may be accomplished while the quenched steel alloy is heated to a temperature of greater than or equal to about 460℃ to less than or equal to about 490℃.
Referring to FIG. 4, which shows on the x-axis time 300 and on the y-axis 302 temperature, the process according to the present disclosure as a function of temperature and time is plotted as 304. A conventional steel alloy undergoing a quench and partition process as a function of temperature and time is plotted as 306. As can be seen, plot 306 has multiple plateaus, which, moving from left to right, relate to the higher quench temperature and the partitioning, respectively. Notably, however, the process according to the present disclosure requires allows for a quenching at a lower temperature and omits partitioning altogether.
As noted above, the zinc coated steel alloy according to the present disclosure yet may result in a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite, even without the higher quench temperature and partitioning required by steel alloys used in conventional quench and partition processes.
The zinc coated steel alloy according to the present disclosure provides excellent strength. More specifically, the zinc coated steel alloy according to the present disclosure may have an ultimate tensile strength of greater than or equal to about 1000 MPa. Further, the zinc coated steel alloy according to the present disclosure provides good  elongation. More specifically, the zinc coated steel alloy according to the present disclosure may have an elongation of greater than or equal to about 25％.
As mentioned above, the zinc coated steel alloy according to the present disclosure is lightweight. More specifically, the zinc coated steel alloy material having compositions according to the present disclosure may be on average from greater than or equal to about 3％to less than or equal to about 6％lighter than the steel alloys described above used in conventional quench and partition processes and may have a density of from greater than or equal to about 7.3 g/cm3 to less than or equal to about 7.6 g/cm3. Moreover, as noted above, many metal parts can be made using the compositions according to the present disclosure to form vehicle components. Vehicles having metal parts made using the compositions according to the present disclosure therefore potentially translate to weight savings. Reducing the weight of components in part is important for improving efficiency and is of great importance for fuel efficiency in mobile applications, such as in automobiles.
In another example, a process may consist essentially of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25℃ to less than or equal to about 100℃. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy is comprised of carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to  about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities. In certain other variations, the process may be further limited as further consisting essentially of any of, any combination of, or all of the following: (1) quenching in a bath； (2) quenching at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second； (3) heating the quenched steel alloy prior to galvanization； (4) having a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite； (5) having an ultimate tensile strength of greater than or equal to about 1000 MPa； and (6) galvannealing after galvanizing the steel alloy. Notably, the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy. Moreover, the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
In another example, a process may consist essentially of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25℃ to less than or equal to about 100℃. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy has a  multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite. In certain other variations, the process may be further limited as further consisting essentially of any of, any combination of, or all of the following: (1) quenching in a bath； (2) quenching at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second； (3) heating the quenched steel alloy prior to galvanization； (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities； (5) having an ultimate tensile strength of greater than or equal to about 1000 MPa； and (6) galvannealing after galvanizing the steel alloy. Notably, the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy. Moreover, the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
In another example, a process may consist essentially of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal  to about 25℃ to less than or equal to about 100℃. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa. In certain other variations, the process may be further limited as further consisting essentially of any of, any combination of, or all of the following: (1) quenching in a bath； (2) quenching at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second； (3) heating the quenched steel alloy prior to galvanization； (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities； (5) having a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite； and (6) galvannealing after galvanizing the steel alloy. Notably, the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy. Moreover, the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
In another example, a process may consist of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of period of greater  than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25 ℃ to less than or equal to about 100℃. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy is comprised of carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities. In certain other variations, the process may be further limited as further consisting of any of, any combination of, or all of the following: (1) quenching in a bath； (2) quenching at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second； (3) heating the quenched steel alloy prior to galvanization； (4) having a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite； (5) having an ultimate tensile strength of greater than or equal to about 1000 MPa； and (6) galvannealing after galvanizing the steel alloy. Notably, the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the galvanized steel alloy. Moreover, the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
In another example, a process may consist of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or  equal to about 800℃ to less than or equal to about 900℃ for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25 ℃ to less than or equal to about 100℃. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The zinc coated steel alloy has a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite. In certain other variations, the process may be further limited as further consisting of any of, any combination of, or all of the following: (1) quenching in a bath； (2) quenching at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second； (3) heating the quenched steel alloy prior to galvanization； (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities； (5) having an ultimate tensile strength of greater than or equal to about 1000 MPa； and (6) galvannealing after galvanizing the steel alloy. Notably, the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy. Moreover, the quenching temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
In another example, a process may consist of introducing a steel alloy into an austenitizing furnace and heating the steel alloy to a temperature of from greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of period of greater than or equal to about 1 minute to less than or equal to about 10 minutes, followed by quenching the austenitized steel alloy to a temperature of greater than or equal to about 25 ℃ to less than or equal to about 100℃. The quenched steel alloy is then galvanized. The zinc coated steel alloy is then cooled. The coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa. In certain other variations, the process may be further limited as further consisting of any of, any combination of, or all of the following: (1) quenching in a bath； (2) quenching at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second； (3) heating the quenched steel alloy prior to galvanization； (4) having a steel alloy comprised of carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities； (5) having a multiphase microstructure comprising greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite； and (6) galvannealing after galvanizing the steel alloy. Notably, the process excludes a conventional partitioning step, which results in cost saving benefits as less energy need be expended to form the zinc coated steel alloy. Moreover, the quenching  temperature is lower than that of quenching and partitioning processes using conventional steel alloys.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims (21)

  1. A method of producing a zinc coated steel alloy comprising:
    austenitizing a steel alloy by heating the steel alloy to a temperature of greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes；
    quenching the steel alloy to a temperature of from greater than or equal to about 25℃ to less than or equal to about 100℃； and
    galvanizing the steel alloy to form a zinc coated steel alloy, wherein the steel alloy comprises carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities.
  2. The method of claim 1, wherein the zinc coated steel alloy comprises greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite.
  3. The method of claim 1, further comprising heating the quenched steel alloy prior to galvanization.
  4. The method of claim 1, further comprising heating the zinc coated steel alloy to a temperature of from greater than or equal to about 500℃ to less than or equal to about 565℃ for a period of less than or equal to about 10 seconds.
  5. The method of claim 1, wherein the quenching occurs at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second.
  6. The method of claim 1, wherein the quenching is conducted in a bath.
  7. The method of claim 1, wherein the zinc coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa.
  8. A method of producing a zinc coated steel alloy comprising:
    austenitizing a steel alloy by heating the steel alloy to a temperature of greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes；
    quenching the steel alloy to a temperature of from greater than or equal to about 25℃ to less than or equal to about 100℃； and
    galvanizing the steel alloy to form a zinc coated steel alloy, wherein the steel alloy comprises greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite.
  9. The method of claim 8, wherein the zinc coated steel alloy comprises carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％；silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal  to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities.
  10. The method of claim 8, further comprising heating the quenched steel alloy prior to galvanization.
  11. The method of claim 8, further comprising heating the zinc coated steel alloy to a temperature of from greater than or equal to about 500℃ to less than or equal to about 565℃ for a period of less than or equal to about 10 seconds.
  12. The method of claim 8, wherein the quenching occurs at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second.
  13. The method of claim 8, wherein the quenching is conducted in a bath.
  14. The method of claim 8, wherein the zinc coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa.
  15. A method of producing a zinc coated steel alloy comprising:
    austenitizing a steel alloy by heating the steel alloy to a temperature of greater than or equal to about 800℃ to less than or equal to about 900℃ for a period of greater than or equal to about 1 minute to less than or equal to about 10 minutes；
    quenching the steel alloy to a temperature of from greater than or equal to about 25℃ to less than or equal to about 100℃； and
    galvanizing the steel alloy to form a zinc coated steel alloy, wherein the zinc coated steel alloy has an ultimate tensile strength of greater than or equal to about 1000 MPa.
  16. The method of claim 15, wherein the steel alloy comprises greater than or equal to about 50 vol. ％to less than or equal to about 65 vol. ％ferrite； greater than or equal to about 15 vol. ％to less than or equal to about 40 vol. ％martensite； and greater than or equal to about 10 vol. ％to less than or equal to about 20 vol. ％metastable retained austenite.
  17. The method of claim 15, wherein the zinc coated steel alloy comprises carbon at greater than or equal to about 0.35 wt. ％to less than or equal to about 0.45 wt. ％； silicon at less than or equal to about 0.5 wt. ％； manganese at greater than or equal to about 0.5 wt. ％to less than or equal to about 1.5 wt. ％； aluminum at greater than or equal to about 3 wt. ％to less than or equal to about 5 wt. ％； chromium at less than or equal to about 1 wt. ％； and a balance of iron and impurities.
  18. The method of claim 15, further comprising heating the quenched steel alloy prior to galvanization.
  19. The method of claim 15, further comprising heating the zinc coated steel alloy to a temperature of from greater than or equal to about 500℃ to less than or equal to about 565℃ for a period of less than or equal to about 10 seconds.
  20. The method of claim 15, wherein the quenching occurs at a rate of greater than or equal to about 20℃ per second to less than or equal to about 30℃ per second and the quenching is conducted in a bath.
  21. The method of claim 15, wherein zinc coated steel alloy has a density of greater than or equal to about 7.3 g/cm3 to less than or equal to about 7.6 g/cm3.
PCT/CN2016/080626 2016-04-29 2016-04-29 Low density zinc-coated steel produced by austenitizing and quench process WO2017185320A1 (en)

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CN110129673A (en) * 2019-05-21 2019-08-16 安徽工业大学 A kind of 800MPa grades of high strength and ductility Q&P steel plate and preparation method thereof
CN115279944A (en) * 2020-02-28 2022-11-01 奥钢联钢铁有限责任公司 Method for producing a hardened steel component with a zinc alloy corrosion protection layer

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CN104630647A (en) * 2015-02-02 2015-05-20 大连理工大学 Preparation method of high-strength hot galvanizing Q&P steel
WO2015152263A1 (en) * 2014-03-31 2015-10-08 新日鐵住金株式会社 Hot-stamping steel material

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CN1548570A (en) * 2001-10-19 2004-11-24 住友金属工业株式会社 Thin steel plate with excellent workability and forming precision and producing process thereof
WO2015152263A1 (en) * 2014-03-31 2015-10-08 新日鐵住金株式会社 Hot-stamping steel material
CN104630647A (en) * 2015-02-02 2015-05-20 大连理工大学 Preparation method of high-strength hot galvanizing Q&P steel

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Publication number Priority date Publication date Assignee Title
CN110129673A (en) * 2019-05-21 2019-08-16 安徽工业大学 A kind of 800MPa grades of high strength and ductility Q&P steel plate and preparation method thereof
CN115279944A (en) * 2020-02-28 2022-11-01 奥钢联钢铁有限责任公司 Method for producing a hardened steel component with a zinc alloy corrosion protection layer
CN115279944B (en) * 2020-02-28 2023-09-26 奥钢联钢铁有限责任公司 Method for producing a hardened steel component having a zinc alloy corrosion protection layer

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