Pulver för 3D-metalltryckning

Översikt

Pulver för 3d-metalltryckning, also known as additive manufacturing or direct metal laser sintering, is a revolutionary production technique that enables the creation of complex metal parts directly from digital designs. A laser selectively fuses fine metallic powder, layer by layer, until the finished 3D object emerges.

The key component that enables this transformative technology is the metal powder. The characteristics and quality of the powder have a significant impact on the mechanical properties, accuracy, surface finish, and overall performance of printed metal parts.

This article provides a comprehensive overview of metal powders for 3D printing. We examine powder types, compositions, properties, specifications, applications, advantages, limitations and more based on the latest industry research and standards. Read on for deeper insights into this fascinating material at the heart of the next industrial revolution.

Typer av Pulver för 3d-metalltryckning

Several alloys and metal materials can be used for 3D printing powder. The most common options include:

Pulver av rostfritt stål

Stainless steel is one of the most popular metals for 3D printing due to its high strength, corrosion resistance and ability to withstand high temperatures. The most common stainless steel alloys used are:

• 316L stainless steel – The standard alloy with excellent corrosion resistance and mechanical properties. 316L has a low carbon content to minimize residual stress during printing.
• 17-4PH stainless steel – Precipitation hardened stainless steel that can achieve very high yield and ultimate tensile strengths through heat treatment after printing.
• 15-5PH stainless steel – Another precipitation hardening stainless steel capable of high strength and hardness. 15-5PH offers better corrosion resistance than 17-4PH.
• Duplex stainless steels – Alloys with a mixed ferritic-austenitic microstructure. Duplex steels offer superior yield and tensile strengths compared to austenitic 316L steel. Common duplex alloys include 2205 and 2304.

Verktygsstål

Tool steels have very high hardness, wear resistance and compressive strength. Common metal powders in this group include:

• H13 tool steel – An extremely versatile Cr-Mo-V hot work tool steel that maintains high hardness and stability at elevated temperatures.
• P20 tool steel – A versatile low alloy mold steel with good machinability and polishability. P20 is often used as a cheaper alternative to H13 tool steel.
• Maraging steels – ‘Maraging’ stands for martensitic aging. These steels achieve ultra-high strengths through aging heat treatment. Common maraging alloys are 18Ni(350) and 18Ni(300).

Aluminiumlegeringar

Aluminum’s light weight, corrosion resistance and high thermal conductivity make it a popular choice for aerospace, automotive and high heat applications. Common aluminum powders include:

• AlSi10Mg – The most widely used aluminum alloy with excellent fluidity, stability and mechanical properties. Si and Mg act as strengthening agents.
• AlSi7Mg – Very similar to AlSi10Mg. Lower silicon content improves powder flowability.
• Scalmalloy – A high-strength Al-Mg-Sc alloy that gets exceptional yield strength from the scandium additions.

Cobalt & Nickel Super Alloys

These advanced metal powders have extremely high heat and wear resistance thanks to their complex compositions. Typical alloys include:

• Inconel 718 – A nickel-chromium based superalloy with incredible high temperature strength through solid-solution and precipitation hardening heat treatments.
• Inconel 625 – Excellent oxidation and corrosion resistance even at extreme temperatures. Used widely in aerospace, chemical and marine applications.
• Cobalt-chrome (CoCr) – Cobalt strengthened by chromium carbides makes biocompatible implants like prosthetics and dental crowns/bridges.
• Hastelloy – Corrosion resistant nickel alloys with additions like molybdenum, chromium and tungsten.

Titan och titanlegeringar

Pure titanium offers the ultimate mix of high strength with low density. Alloying elements like aluminum, vanadium and iron provide additional benefits:

• Ti6Al4V – The most popular titanium alloy with aluminum stabilizing the alpha phase and vanadium strengthening the beta phase.
• TiAl6V4 – Higher aluminum content further improves mechanical properties and oxidization resistance.
• Ti6Al4V ELI – ‘ELI’ stands for extra low interstitial with lower oxygen, nitrogen and carbon. Has improved fracture resistance over regular Ti64.

Refractory & Intermetallic Alloys

These advanced powders can withstand extreme temperatures or have exceptional strength/hardness:

• Tungsten carbide (WC/Co) – Hard tungsten carbides held together by cobalt binder phase makes this alloy stiffer than steel while maintaining toughness.
• Molybden (Mo) – Pure molybdenum powder creates parts with high heat resistance able to withstand temperatures exceeding 750°C.
• Inconel 625 – Nickel-chromium based superalloy powder creates objects that retain high strength in oxidizing environments up to 980°C .

Ädelmetaller

The unique properties of precious metals like gold, silver and platinum also make them suitable for 3D printing:

• Silver (Ag) – Pure silver powder preserves excellent electrical and thermal conductivity properties even in complex printed geometries.
• Guld (Au) – Most printed gold is actually gold alloyed with small amounts of metals like silver, copper and palladium to improve hardness and optimize properties.
• Platina (Pt) – Platinum powder is biocompatible and resistant to corrosion and chemical attack. Used to make medical implants and laboratory equipment.

This table summarizes the characteristics of the most common metal printing powders:

Metoder för produktion av metallpulver

To achieve properties necessary for high quality 3D printing, metallic powders must have certain specific physical characteristics and particles size distributions. There are several powder production techniques used:

Atomisering av gas

• Molten metal stream is disintegrated by high pressure inert gas jets
• Produces spherical powder ideal for printing – high flowability, packing density
• Most common method for finer stainless steel, tool steel, superalloy & titanium powders

Atomisering av vatten

• Uses water jets to break up molten metal into fine droplets
• Irregular powder shape affects flow but cheaper than gas atomization
• Typically used for more affordable options like aluminum and magnesium

Plasmaatomisering

• Very high energy plasma arc melts and disperses metal into fine particles
• Generates highly spherical powders from reactive alloys like titanium aluminides
• Powders have higher purity and can print intricate details more accurately

Induktionssmältning med elektrod och gasatomisering (EIGA)

• Combines induction melting and gas atomization
• Exceptional control over chemical composition and cleanliness
• Used for specialty alloys like nickel superalloys and precious metals

Mekanisk legering

• Powder produced by high energy ball milling process
• Used for CMD copper alloys, aluminum composites and intermetallics
• Generates fine homogeneous compositions from blended elemental powders

Proper powder production technique is critical for getting desired alloy chemistry, particle shapes, size distribution, purity levels, and flow characteristics essential for high quality metal 3D printing.

Metal Powder Characteristics

3D printing powders must conform to strict specifications in terms of chemistry, particle size distribution, morphology, microstructure and other parameters. Key characteristics include:

Fördelning av partikelstorlek

Typical range is 15 microns to 45 microns. Critical factors include:

• D10 – Size below which 10% of particles fall
• D50 – Median particle size with 50% above and below this diameter
• D90 – Size where 90% of powder is below this diameter

Ideal values: D10: 20-25 μm ; D50: 30-35 μm ; D90: 40-45 μm

Particle Shape & Surface Morphology

• Highly spherical particles with smooth surfaces enable easiest powder spreading and best densification.

Flow Rate & Apparent Density

• Flow rate determines ease of powder spreading during printing
• Apparent density indicates how densely powder packs together in a fixed volume
• Values depend on factors like particle shape, size distribution, surface structure
• Gas atomized powders have highest flowability and packing density

Tappdensitet

• Maximum density achieved after mechanical tapping/agitation
• Higher tap density improves final part density

Hausner-kvot

• The ratio between tap density and apparent density
• Lower ratios ~1.1 indicate good flowability
• Higher ratios ~1.4 suggest cohesiveness and poor flow

Residual Oxides & Impurities

• Purity is critical, oxygen and nitrogen can cause porosity defects
• Chemistries must conform to alloy specifications
• Gas, plasma and EIGA atomization offer cleanest powders

Intern mikrostruktur

• Depends on composition, solidification rates during powder production
• Single phase, equiaxed grains desired for optimal layered fusion
• Some alloys intentionally create dual phases for unique properties

Particle Hardness

• Influences performance of finished parts
• Vicker’s pyramid number (HV) used to quantify
• Hard particles resist deformation during powder spreading

Satellite Formation

• Smaller particles can bind to larger particles during powder production
• Satellites can influence melt pool formation during printing
• Gas atomized powders have minimal satellites

Surface Chemistry

• Surface functional groups influence powder spreading + fusion
• Atmosphere and temperature during production have an effect
• Inert processing generates clean, oxide-free powder chemistry

Maintaining stringent quality control over these powder characteristics is crucial for successful high quality 3D printing.

Specifikationer för metallpulver

3D printer manufacturers and organizations like ISO and ASTM have standardized specifications for most metal printing powders. Typical parameters include:

Storleksfördelning

• D10, D50, D90 values following recommended ranges
• Maximum satellite content < 1%

Chemistry Conformance

• Elemental composition meeting published alloy composition ranges
• Low oxygen and nitrogen levels (<1000 ppm)
• Residual carbon and sulfur amounts depending on alloy

Skenbar densitet och tappdensitet

• Apparent density 2.5-4.5 g/cm3
• Tap density up to 65% higher than apparent density

Flödeshastighet

• Hall flowmeter test > 15 s/50 g

Fukthalt

• High humidity causes powder agglomeration
• Maximum moisture content < 0.02%

Surface Oxides

• Oxides and contaminants can cause porosity defects
• SEM imaging to check particle surfaces

Reputable powder manufacturers test every batch and provide full assay data as well as MLS ratios, Hausner ratios, Carr indices, and Pycnometer and Hall Flowmeter results to qualify powder to established norms.

Metal Printing Powder Applications

3D metal printing transforms production across diverse industries. Typical applications include:

Flyg- och rymdindustrin

• Aircraft and rocket engine components – turbines, nozzles, fuel systems
• Structural airframe and landing gear parts made from titanium, aluminum, Inconel
• Significant weight savings, part consolidation, performance improvements

Medicin & tandvård

• Joint reconstruction implants like knees, hips, shoulders
• Dental implants, crowns and bridges
• Cranial plates, surgical instruments, patient-matched guides & tools
• Biocompatible cobalt chrome, titanium, stainless steel and precious alloys

Fordon

• Light weighting prototype and production car parts – chassis, drivetrain
• Conformal cooling tooling for injection molding
• Custom jigs, fixtures for assembly lines
• Certification for structural stainless steel components in progress

Industriell tillverkning

• Metal tooling – injection molding, thermoforming, sheet metal forming
• Press and stamping dies from hardened tool steels
• Conformal cooling channels minimize tool cycle times
• Rapid turnaround of short run production tooling

Olja & Gas

• Stainless steel and Hastelloy valves, pumps, pipes for production
• Corrosion resistant Inconel components for offshore
• Conformal channels minimize pressure drop losses

Konsumentelektronik

• Customized stainless steel or aluminum enclosures, shields, frames
• Thermal management devices for heat dissipation
• Electromagnetic shielding components
• High end designer jewelry – gold, silver, platinum

Rapid manufacturing techniques like 3D printing unlock game-changing functionality, performance and design freedom. The unique properties of metal printing powders empower production-ready end use parts across nearly every industry.

Pulver för 3d-metalltryckning Leverantörer

Most major metal manufacturing conglomerates now produce specialized powders dedicated for additive manufacturing. Some of leading global suppliers include:

Reputable suppliers provide comprehensive composition and properties data for their powders backed by intensive R&D and stringent quality control. Many offer custom alloy development services as well. Global supply chain logistics ensure reliable availability across major markets.

3d metal printing powder Pricing

Rostfritt stål 316L – $50-100 USD per kg

Maraging Steel (300 Grade) – $100-200 USD per kg

Aluminium AlSi10Mg – $30-60 USD per kg

Titanium Ti6Al4V (Grade 5) – $200-400 USD per kg

Inconel 718 – $100-200 USD per kg

Kobolt krom F75 – $100-250 USD per kg

Priserna varierar beroende på:

• Renhetsnivåer
• Storleksfördelning
• Minimum order quantities
• Custom alloy development charges
• Import duties/taxes

Pros vs Cons of Metal 3D Printing

Fördelar

• Design freedom for complex geometries
• Part consolidation into single components
• Weight reduction from topology optimization
• Reduced assembly from fewer components
• High strength alloy options
• Functional integration – eg conformal cooling channels
• Rapid turnaround foriterations and customization
• On-demand production of obsolete/legacy spares
• Reduced material waste relative to subtractive techniques

Begränsningar

• Higher part costs compared to high volume conventional manufacturing
• Restricted size capability based on equipment build volume
• Limited variety of alloy options currently certified and qualified
• Lower dimensional accuracy and finer surface finishes require secondary machining
• Mechanical anisotropy since properties differ depending on build orientation
• Post processing like Hot Isostatic Pressing needed for full density consolidation
• Lack of industry standards for some applications

The range of metals printable is expanding exponentially together with quality and repeatability as the technology and materials science continues advancing rapidly.

VANLIGA FRÅGOR

What particle size range do metal powders for 3D printing need?

• Typical size range is 15-45 microns
• Distribution curves specify D10, D50 and D90 particle diameters
• Values depend on desired layer resolution but commonly 20-45 microns

What’s the difference between stainless steel 316L and 17-4PH powders?

• Both iron/chromium/nickel alloys. 316L has better corrosion resistance.
• 17-4PH has higher strength and hardness after precipitation hardening heat treatment
• 316L sees more marine, chemical and biomedical uses needing corrosion resistance
• 17-4PH suits tooling applications needing high wear resistance

Why is shape important for metal printing powders?

• Highly spherical particles have better flow and high packing density
• Smooth surface morphology without satellites ensures optimal fusion
• Gas atomized powders yield finest quality prints.

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