Best IN939 Powder for 3D Printing in 2023

Overview of IN939 Powder for 3D Printing

IN939 is a high-performance nickel-based superalloy powder designed for additive manufacturing of critical components needing exceptional mechanical properties at high temperatures. This article provides a comprehensive guide to IN939 powder for 3D printing applications across aerospace, automotive, energy and industrial sectors.

Key aspects covered include IN939 composition, properties, print parameters, applications, specifications, suppliers, handling, inspection, comparisons to alternatives, advantages and limitations, and frequently asked questions. Quantitative data is presented in easy-to-reference tables.

Composition of IN939 Powder

IN939 has a complex precipitation hardening alloy composition:

Element	Weight %	Purpose
Nickel	Balance	Principal matrix element
Chromium	15 – 18	Oxidation resistance
Aluminum	3.8 – 4.8	Precipitation hardening
Titanium	0.9 – 1.4	Precipitation hardening
Cobalt	12 – 15	Solid solution strengthening
Tantalum	3.8 – 4.8	Carbide former
Carbon	0.05 – 0.15	Carbide former
Boron	0.006 – 0.012	Grain boundary strengthener

Trace quantities of zirconium, magnesium and sulphur are also added for enhanced properties.

Properties of IN939 Powder

IN939 possesses an exceptional combination of properties:

Property	Description
High strength	Excellent tensile and creep rupture strength up to 1050¡«C
Thermal stability	Strength maintained up to 1000¡«C
Creep resistance	High stress-rupture life at high temperatures
Oxidation resistance	Forms protective Cr2O3 oxide scale
Thermal fatigue resistance	Resists cracking during thermal cycling
Phase stability	Microstructure stable after prolonged exposures
Corrosion resistance	Resistant to hot corrosion, oxidation, sulfidation

The properties enable use under extreme thermal and mechanical loads.

3D Printing Parameters for IN939 Powder

Typical AM processing parameters for IN939 include:

Parameter	Typical value	Purpose
Layer thickness	20-50 Ã×m	Resolution vs build speed
Laser power	250-500 W	Sufficient melting without evaporation
Scan speed	800-1200 mm/s	Density vs production rate
Hatch spacing	100-200 Ã×m	Mechanical properties
Support structure	Minimal	Easy removal
Hot isostatic pressing	1160¡«C, 100 MPa, 3h	Eliminate porosity

Parameters are optimized for attributes like density, microstructure, build rate, and post-processing requirements.

Applications of 3D Printed IN939 Parts

Additively manufactured IN939 components serve critical applications including:

Industry	Components
Aerospace	Turbine blades, vanes, combustors
Power generation	Hot gas path parts, heat exchangers
Automotive	Turbocharger wheels, valves
Chemical processing	Pumps, valves, reaction vessels

Benefits over conventionally processed IN939 include complex geometries and reduced lead time.

Specifications of IN939 Powder for 3D Printing

IN939 powder for AM must meet exacting specifications:

Parameter	Specification
Particle size	15-45 Ã×m typical
Particle shape	Spherical morphology
Apparent density	> 4 g/cc
Tap density	> 6 g/cc
Hall flow rate	> 23 sec for 50 g
Purity	>99.9%
Oxygen content	<100 ppm

Tighter tolerances, custom size distributions, and controlled impurity levels available.

Suppliers of IN939 Powder

Reputable suppliers of IN939 powder include:

Supplier	Location
Sandvik Osprey	UK
Carpenter Additive	USA
Praxair	USA
AP&C	Canada
Erasteel	Sweden
AMETEK	USA

Pricing for IN939 powder ranges from $110/kg to over $220/kg based on quality and order volume.

Handling and Storage of IN939 Powder

As a reactive powder, careful handling of IN939 is needed:

• Store sealed containers in a cool, inert atmosphere
• Prevent contact with moisture, oxygen, acids
• Use properly grounded equipment
• Avoid dust accumulation to minimize explosion risk
• Local exhaust ventilation recommended
• Wear appropriate PPE while handling

Proper techniques and controls prevent IN939 powder oxidation or contamination.

Inspection and Testing of IN939 Powder

IN939 powder is validated using:

Method	Parameters Tested
Sieve analysis	Particle size distribution
SEM imaging	Particle morphology
EDX	Chemistry and composition
XRD	Phases present
Pycnometry	Density
Hall flow rate	Powder flowability

Testing per applicable ASTM standards ensures batch consistency.

Comparing IN939 to Alternative Alloy Powders

IN939 compares to other Ni-based superalloys as:

Alloy	High Temperature Strength	Cost	Printability	Ductility
IN939	Excellent	High	Excellent	Low
IN738	Good	Medium	Excellent	Medium
IN718	Fair	Low	Good	Excellent
Hastelloy X	Excellent	High	Fair	Medium

For balanced properties and processability, IN939 supersedes alternatives like IN718 or Hastelloy X.

Pros and Cons of IN939 Powder for 3D Printing

Pros	Cons
Exceptional high temperature strength	Expensive compared to IN718
Excellent oxidation and creep resistance	Significant parameter optimization needed
Complex geometries feasible	Limited room temperature ductility
Faster processing than cast/wrought	Controlled storage and handling environment
Comparable properties to cast alloy	Difficult to machine after printing

IN939 enables high-performance printed parts but with higher costs and controlled processing needs.

Frequently Asked Questions about IN939 Powder for 3D Printing

Q: What particle size range works best for printing IN939?

A: A particle size range of 15-45 microns provides good flowability combined with high resolution and density. Finer particles below 10 microns can improve density and surface finish.

Q: Does IN939 require any post-processing after 3D printing?

A: Post processes like hot isostatic pressing, heat treatment, and machining are usually needed to eliminate porosity, relieve stresses, and achieve final tolerances and surface finish.

Q: What precision can be achieved with IN939 printed parts?

A: After post-processing, dimensional accuracy and surface finish comparable to CNC machined parts can be achieved with IN939 AM components.

Q: Are support structures necessary for printing IN939 powder?

A: Minimal supports are recommended for complex channels and overhangs to prevent deformation and facilitate easy removal. IN939 powder has good flowability.

Q: What alloy powder is the closest alternative to IN939 for AM?

A: IN738 is the closest alternative in terms of balanced properties and maturity for additive manufacturing. Other alloys like IN718 or Hastelloy X have some trade-offs.

Q: Is IN939 compatible with direct metal laser sintering (DMLS)?

A: Yes, IN939 is readily processable by major powder bed fusion techniques including DMLS along with selective laser melting (SLM) and electron beam melting (EBM).

Q: What density is achievable with 3D printed IN939 components?

A: With optimized parameters, densities over 99% are achievable, matching properties of traditionally processed IN939 products.

Q: How do the properties of printed IN939 compare to cast alloy?

A: Additively manufactured IN939 exhibits comparable or better mechanical properties and microstructure compared to conventional cast and wrought forms.

Q: What defects can occur when printing with IN939 powder?

A: Potential defects are cracking, distortion, porosity, surface roughness, incomplete fusion etc. Most can be prevented by proper parameter optimization and powder quality.

Q: Is hot isostatic pressing (HIP) mandatory for IN939 AM parts?

A: HIP eliminates internal voids and improves fatigue resistance. For less demanding applications, heat treatment alone may suffice instead of HIP.