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US-12624432-B2 - Metal powder for additive manufacturing

US12624432B2US 12624432 B2US12624432 B2US 12624432B2US-12624432-B2

Abstract

A metal powder having a composition including the following elements, expressed in content by weight: 6.5%≤Si≤10%, 4.5%≤Nb≤10%, 0.2%≤B≤2.0%, 0.2%≤Cu≤2.0%, C≤2% and optionally containing Ni≤10 wt % and/or Co≤10 wt % and/or Cr≤7 wt % and/or Zr as a substitute for any part of Nb on a one-to-one basis and/or Mo as a substitute for any part of Nb on a one-to-one basis and/or P as a substitute for any part of Si on a one-to-one basis, the balance being Fe and unavoidable impurities resulting from the elaboration, the metal powder having a microstructure including at least 5% in area fraction of an amorphous phase, the balance being made of crystalline ferritic phases with a grain size below 20 μm and possible precipitates, the metal powder having a mean sphericity SPHT of at least 0.80.

Inventors

  • Manuel SANCHEZ PONCELA
  • Nele Van Steenberge
  • Florencia GATTI
  • Sandra Rodriguez

Assignees

  • ARCELORMITTAL

Dates

Publication Date
20260512
Application Date
20201218
Priority Date
20191219

Claims (20)

  1. 1 . A metal powder having a composition comprising the following elements, expressed in content by weight: 6.5%≤Si≤10% 4.5%≤Nb≤10% 0.2%≤B≤2.0% 0.2%≤Cu≤2.0% C≤2% and optionally containing: Ni≤10 wt %, Co≤10 wt %, Cr≤7 wt %, Zr as a substitute for any part of Nb on a one-to-one basis, Mo as a substitute for any part of Nb on a one-to-one basis, P as a substitute for any part of Si on a one-to-one basis, one or more additional elements selected from a group consisting of Hf, Ta, W, V and Y and wherein a content by weight of each additional element is less than 3.5% and/or, one or more rare earth metals, wherein a content by weight of each rare earth metal is less than 0.2%, a balance being Fe and unavoidable impurities resulting from processing, the metal powder having a microstructure comprising at least 5% in area fraction of an amorphous phase, a microstructure balance being made of crystalline ferritic phases with a grain size below 20 μm and possible precipitates, the metal powder having a mean sphericity SPHT of at least 0.80, at least 20% of grains in the crystalline ferritic phase having a grain size of at least 1 μm.
  2. 2 . The metal powder as recited in claim 1 wherein the grain size of the ferritic phase is below 10 μm.
  3. 3 . The metal powder as recited in claim 1 wherein not more than 7% of the particles composing the metal powder have a sphericity SPHT inferior to 0.70.
  4. 4 . The metal powder as recited in claim 1 wherein the mean aspect ratio of the particles composing the metal powder is above 0.71.
  5. 5 . The metal powder as recited in claim 1 wherein at least 80% of the particles composing the metal powder have a size in the range of 15 μm to 170 μm.
  6. 6 . The metal powder as recited in claim 1 wherein the microstructure comprises at most 45% in area fraction of the amorphous phase.
  7. 7 . The metal powder as recited in claim 1 wherein the crystalline ferritic phases of the microstructure are Fe-α(Si) and Fe3Si (DO3).
  8. 8 . The metal powder as recited in claim 1 wherein at least 40% of grains in the crystalline ferritic phase having a grain size of at least 1 μm.
  9. 9 . The metal powder as recited in claim 8 wherein at least 10% of grains in the crystalline ferritic phase having a grain size of below 0.1 μm.
  10. 10 . The metal powder as recited in claim 1 wherein at least 10% of grains in the crystalline ferritic phase having a grain size of below 0.1 μm.
  11. 11 . The metal powder as recited in claim 1 wherein 0.01%≤C≤0.07%.
  12. 12 . The metal powder as recited in claim 1 wherein 0.01%≤C≤2.0%.
  13. 13 . A method for manufacturing the metal powder as recited in claim 1 , the method comprising: (i) melting metals and/or alloys at a temperature at least 150° C. above the liquidus temperature so as to obtain a melt having the composition as recited in claim 1 , and (ii) atomizing the melt through a nozzle having a diameter of at most 4 mm, with a gas pressurized between 10 and 30 bar.
  14. 14 . The method as recited in claim 13 wherein the metals and/or alloys comprise FeSi ferroalloy, FeB ferroalloy, FeNb ferroalloy, Cu and Fe.
  15. 15 . The method as recited in claim 13 wherein the melting is done at a temperature at maximum 450° C. above the liquidus temperature.
  16. 16 . The method as recited in claim 13 wherein the melting is done at a temperature at least 300° C. above the liquidus temperature.
  17. 17 . The method as recited in claim 13 wherein the gas is pressurized between 14 and 18 bar.
  18. 18 . The method as recited in claim 13 wherein the nozzle diameter is between 2 and 3 mm.
  19. 19 . The method as recited in claim 13 wherein the gas to metal ratio defined as a ratio of gas flow rate in Kg/h to melt flow rate in Kg/h is between 1.5 and 7.
  20. 20 . The method as recited in claim 13 further comprising subsequently drying the metal powder.

Description

The present invention relates to a metal powder for the manufacturing of steel parts and in particular for their additive manufacturing. The present invention also relates to the method for manufacturing the metal powder. BACKGROUND Fe-based bulk metallic glasses (BMGs) have been attracting much attention due to their excellent soft-magnetic property, high corrosion resistance, good mechanical properties, etc. They have been utilized as high-efficient magnetic middle and high-frequency transformers in the electric and electronic industries. However, until now, most Fe-based BMGs with good soft magnetic properties can only be produced in very complex process conditions. The liquid compositions have to be casted with a high cooling rate between chilled rolls to obtain an amorphous material generally in the form of a thin ribbon. They are subsequently annealed in very unique process conditions to produce materials of nanocrystalline type. Furthermore, they can only be produced in thin ribbons which drastically limit their use. SUMMARY OF THE INVENTION It is an object of the present invention to remedy the drawbacks of the prior art by providing Fe-based BMGs which can be easily produced and easily processed to obtain final parts. The present invention provides a metal powder having a composition comprising the following elements, expressed in content by weight: 6.5%≤Si≤10%4.5%≤Nb≤10%0.2%≤B≤2.0%0.2%≤Cu≤2.0%C≤2% and optionally containing: Ni≤10 wt % and/or,Co≤10 wt % and/or,Cr≤7 wt % and/or,Zr as a substitute for any part of Nb on a one-to-one basis and/or,Mo as a substitute for any part of Nb on a one-to-one basis and/or,P as a substitute for any part of Si on a one-to-one basis and/or,one or more additional elements selected from among: Hf, Ta, W, V or Y and wherein a content by weight of each additional element is less than 3.5% and/or,one or more rare earth metals, wherein a content by weight of each rare earth metal is less than 0.2%,the balance being Fe and unavoidable impurities resulting from the elaboration, the metal powder having a microstructure comprising at least 5% in area fraction of an amorphous phase, the balance being made of crystalline ferritic phases with a grain size below 20 μm and possible precipitates, the metal powder having a mean sphericity SPHT of at least 0.85. The metal powder according to the invention may also have the optional features listed below, considered individually or in combination: the grain size of the ferritic phases is below 10 μm,not more than 7% of the particles composing the metal powder have a sphericity SPHT inferior to 0.70.the mean aspect ratio of the particles composing the metal powder is above 0.71,at least 80% of the particles composing the metal powder have a size in the range of 15 μm to 170 μm.the microstructure comprises at most 45% in area fraction of the amorphous phase,the crystalline ferritic phases of the microstructure are Fe-α(Si) and Fe3Si (DO3). A second subject of the invention consists of a process for manufacturing a metal powder for additive manufacturing, comprising: (i) Melting elements and/or metal-alloys at a temperature at least 150° C. above the liquidus temperature so as to obtain a molten composition comprising, expressed in content by weight, 6.5%≤Si≤10%, 4.5%≤Nb≤10%, 0.2%≤B≤2.0%, 0.2%≤Cu≤2.0%, C≤2% and optionally containing Ni≤10 wt % and/or Co≤10 wt % and/or Cr≤7 wt % and/or Zr as a substitute for any part of Nb on a one-to-one basis and/or Mo as a substitute for any part of Nb on a one-to-one basis and/or P as a substitute for any part of Si on a one-to-one basis and/or one or more additional elements selected from among: Hf, Ta, W, V or Y and wherein a content by weight of each additional element is less than 3.5% and/or one or more rare earth metals, wherein a content by weight of each rare earth metal is less than 0.2%, the balance being Fe and unavoidable impurities resulting from the elaboration,(ii) Atomizing the molten composition through a nozzle the diameter of which is at most 4 mm, with a gas pressurized between 10 and 30 bar. The process according to the invention may also have the optional features listed below, considered individually or in combination: the elements and/or metal alloys melted together comprise FeSi ferroalloy, FeB ferroalloy, FeNb ferroalloy, Cu and Fe,the melting is done at a temperature at maximum 450° C. above the liquidus temperature,the melting at a temperature at least 300° C. above the liquidus temperature,the gas is pressurized between 14 and 18 bar,the nozzle diameter is between 2 and 3 mm,the gas to metal ratio is between 1.5 and 7,the metal powder is subsequently dried. DETAILED DESCRIPTION The invention will be better understood by reading the following description, which is provided purely for purposes of explanation and is in no way intended to be restrictive. Silicon is present in the composition according to the invention at a content of 6.5 to 10 wt %. Si increases the hardness