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CN-122007439-A - Duplex stainless steel and additive manufacturing method and application thereof

CN122007439ACN 122007439 ACN122007439 ACN 122007439ACN-122007439-A

Abstract

The invention discloses duplex stainless steel and an additive manufacturing method and application thereof, and belongs to the technical field of stainless steel materials. The duplex stainless steel is obtained by carrying out additive manufacturing on stainless steel-based composite powder in a laser powder bed melting mode, wherein the stainless steel-based composite powder comprises 70-90 wt% of 316L stainless steel powder and 10-30 wt% of pure iron powder, and a microstructure of the duplex stainless steel comprises gamma austenite and alpha martensite. The introduction of iron can change the local components and solidification process of a molten pool, obviously reduce the stability of austenite, induce partial austenite to martensite transformation under the actions of rapid cooling and subsequent thermal circulation, and form a gamma austenite and alpha martensite two-phase structure. The invention can make the duplex stainless steel have the characteristics of high strength, high toughness, high wear resistance, low cost and the like on the premise of not obviously damaging the formability and the process adaptability of the material, and can be used in aerospace lightweight structural parts, high-precision dies, nuclear heat dissipation parts and the like.

Inventors

  • LIU JIANYE
  • HUANG ZHENGHUA
  • NIU LIUHUI
  • DENG PU
  • QIN LIN
  • WANG YANHUI
  • HU FUCHAO

Assignees

  • 广东汉邦激光科技有限公司

Dates

Publication Date
20260512
Application Date
20260228

Claims (10)

  1. 1. The duplex stainless steel is characterized by being manufactured by adding materials to stainless steel-based composite powder in a laser powder bed melting mode; the stainless steel-based composite powder comprises 70-90 wt% of 316L stainless steel powder and 10-30 wt% of pure iron powder; The microstructure of the duplex stainless steel comprises gamma austenite and alpha martensite.
  2. 2. The duplex stainless steel of claim 1, wherein the stainless steel-based composite powder comprises 70wt% to 80wt% of 316L stainless steel powder and 20wt% to 30wt% of pure iron powder.
  3. 3. The duplex stainless steel according to claim 1, wherein the particle size of the 316L stainless steel powder is 15-53 μm, and/or the particle size of the pure iron powder is 1-10 μm.
  4. 4. A duplex stainless steel according to any of claims 1-3, further characterized in that the duplex stainless steel has at least one of the following features: The microstructure of the duplex stainless steel contains not less than 8% and not more than 60% of alpha martensite in terms of volume percent; The tensile strength of the duplex stainless steel is 754-1138 MPa; The dual-phase stainless steel is characterized in that the yield strength is 481-849 MPa; The elongation after break of the duplex stainless steel is 13.0% -59.3%; the impact toughness of the duplex stainless steel is 31.6J/cm 2 ~205.2J/cm 2 ; and 6, the hardness of the duplex stainless steel is 16.8-34.9 HRC.
  5. 5. A method for manufacturing a duplex stainless steel additive according to any one of claims 1 to 4, comprising the step of performing additive manufacturing on the stainless steel-based composite powder by a laser powder bed melting method.
  6. 6. An additive manufacturing method according to claim 5, wherein the preparation of the stainless steel-based composite powder comprises mechanically mixing the 316L stainless steel powder and the pure iron powder.
  7. 7. An additive manufacturing method according to claim 5, wherein the laser powder bed melting condition comprises laser power of 150-400W, scanning speed of 500-1500 mm/s, scanning interval of 0.06-0.12 mm, powder spreading layer thickness of 0.03-0.06 mm, scanning strategy of strip scanning and layer-by-layer rotation.
  8. 8. An additive manufacturing method according to any one of claims 5 to 7, wherein the stainless steel obtained by additive manufacturing is subjected to heat treatment.
  9. 9. The additive manufacturing method according to claim 8, wherein the heat treatment comprises furnace cooling or air cooling after annealing at 700 ℃ to 900 ℃ for 1h to 4h; preferably, the heat treatment comprises furnace cooling after annealing at 800 ℃ for 2 hours.
  10. 10. The use of a duplex stainless steel according to any one of claims 1-4 for the manufacture of at least one of aerospace lightweight structural members, high precision molds and nuclear heat dissipating components.

Description

Duplex stainless steel and additive manufacturing method and application thereof Technical Field The invention relates to the technical field of stainless steel materials, in particular to duplex stainless steel and an additive manufacturing method and application thereof. Background The Laser Powder Bed Fusion (LPBF) technique is one of the mainstream processes for metal additive manufacturing, with significant advantages in complex structural part fabrication. 316L stainless steel is one of the metallic materials widely used in LPBF technologies because of its good corrosion resistance, formability and biocompatibility. In the conventional LPBF forming process, the microstructure of 316L stainless steel is typically composed of a single austenitic phase, aided by a small amount of metastable structure, due to the extremely high cooling rate. While this structure provides good ductility and corrosion resistance, it is relatively limited in room temperature strength and hardness, limiting its use in certain structural components that have higher requirements for strength, hardness, and wear resistance. In view of this, the present invention has been made. Disclosure of Invention The invention aims to provide a duplex stainless steel, an additive manufacturing method and an application thereof, so as to solve or improve the technical problems. The invention can be realized as follows: in a first aspect, the present invention provides a duplex stainless steel produced by additive manufacturing of stainless steel-based composite powder by laser powder bed melting; the stainless steel-based composite powder comprises 70-90 wt% of 316L stainless steel powder and 10-30 wt% of pure iron powder; the microstructure of the duplex stainless steel comprises gamma austenite and alpha martensite at the same time. In an alternative embodiment, the stainless steel-based composite powder includes 70wt% to 80wt% 316L stainless steel powder and 20wt% to 30wt% pure iron powder. In alternative embodiments, the 316L stainless steel powder has a particle size of 15 μm to 53 μm and/or the pure iron powder has a particle size of 1 μm to 10 μm. In an alternative embodiment, the duplex stainless steel further has at least one of the following features: The microstructure of the duplex stainless steel contains not less than 8% and not more than 60% of alpha martensite in terms of volume percent; Feature 2: the tensile strength of the duplex stainless steel is 754-1138 MPa; the method is characterized in that the yield strength of the duplex stainless steel is 481-849 MPa; the characteristic 4 is that the elongation after break of the duplex stainless steel is 13.0% -59.3%; The characteristic 5 is that the impact toughness of the duplex stainless steel is 31.6J/cm 2~205.2J/cm2; and 6, the hardness of the duplex stainless steel is 16.8-34.9 HRC. In a second aspect, the present invention provides a method of additive manufacturing a duplex stainless steel according to any of the preceding embodiments, comprising the step of additively manufacturing a stainless steel-based composite powder by laser powder bed melting. In an alternative embodiment, the stainless steel-based composite powder is prepared by mechanically mixing 316L stainless steel powder with pure iron powder. In an alternative embodiment, the laser powder bed melting condition comprises 150-400W of laser power, 500-1500 mm/s of scanning speed, 0.06-0.12 mm of scanning interval, 0.03-0.06 mm of powder spreading layer thickness, and the scanning strategy is that the strips are scanned and rotated layer by layer. In an alternative embodiment, the additive manufactured stainless steel is heat treated. In an alternative embodiment, the heat treatment comprises furnace cooling or air cooling after annealing at 700-900 ℃ for 1-4 hours. In an alternative embodiment, the heat treatment comprises furnace cooling after annealing at 800 ℃ for 2 hours. In a third aspect, the present invention provides the use of a duplex stainless steel according to any of the preceding embodiments for the manufacture of at least one of aerospace lightweight structural members, high precision molds, nuclear heat dissipating components, and the like. The beneficial effects of the invention include: The duplex stainless steel is manufactured by carrying out additive manufacturing on stainless steel-based composite powder in a laser powder bed melting mode, wherein the stainless steel-based composite powder comprises 70-90 wt% of 316L stainless steel powder and 10-30 wt% of pure iron powder, and a microstructure of the duplex stainless steel comprises gamma austenite and alpha martensite. The introduction of the iron element can change the local components and solidification process of a molten pool, obviously reduce the stability of austenite, induce partial austenite to martensite transformation under the actions of rapid cooling and subsequent thermal circulation, and form a two-phase structure of gamma