lecture ti paris rev. 1 (15:30) kopie 2

Titanium powder metallurgy (PM) and additive manufacturing(AM) / 3D printing

April 18-20, 2016 Paris Marriott Rive Gauche Hotel & Conf. Center Paris, FranceChris van Dam, MSc.

Source: Puris W: www.airbornemetals.comE: [email protected]: +31 (0)636529550

Thank you sir.

Good afternoon ladies and gentlemen.

This afternoon, I would like to give you an introduction to titanium powder technology and additive manufacturing, also known as 3D printing.

What I will try to do is to provide a general overview of the current state of affairs from an industrial point of view, focusing on the relevance of these technologies for the aerospace industry.

Consequently, my aim is to provide a global overview without delving into technical details.

At the end of the presentation, I would like to show you a short video showing the 3D printing process.

Subjects coveredRationale for Ti usage in aerospaceApplicationsPM / AM /3DTesting & safetyCost aspectsVideo

Source: TMS Titanium


Following subjects will be covered:

The rationale behind the application of titanium in aerospace, in other words, what makes titanium an interesting material for aerospace applications.

Some typical examples of aerospace applications will be shown.

Powder metallurgy and the AM process will be globally described as well as some aerospace-relevant technologies.

When it comes to testing and safety aspects when handling the material, the new technologies pose some challenges which will be mentioned.

Of course, justification of whether or not to employ the new technologies is highly dependent on economical factors as well, so this will be discussed briefly.

Properties & suitability for aerospace


Source: Boeing

Titanium is a remarkable metal and possesses characteristics that make it a candidate for certain aerospace applications.

Some of these characteristics are:it has about roughly the same strength as steel, but it is much lightergood fatigue properties corrosion resistant resistance to high temperatures, cryogenic temperatures, temperature fluctuations and extreme environments in generalgood machinabilitycreep resistancebiologically inert

Properties are greatly alloy-dependent and can be fine-tuned by processes like heat-treating.

Examples of Defense & Aerospace applicationsLanding gear componentsJet Engine Components(AMG)Rocket components


A few examples of typical aerospace applications are shown here.

In landing gears available space may be a problem. The high strength-to-weight ratio may justify the use of titanium here. Also, these structures are subjected to cyclic loading. Landing gear legs can achieve around 30-40% weight saving compared to steel, with better fatigue life.

Its heat resistance and resistance to temperature fluctuations leads to jet engine applications. Different alloys are used in the various heat zones.

The strength-to-weight ratio and resistance to extreme environments make the material suitable for rockets and space applications.

Titanium powder metallurgy (PM)BenefitsBlended elemental technique (BE)Pre-alloyingPrerequisites


PM potentially offers some very interesting possibilities, like manufacturing net shape or near net shape parts, avoiding machining and recycling costs

It enables virtually any geometry and offers new design possibilities

There are two basic approaches to obtain titanium alloy powder.

These are known as the pre-alloying and the blended elemental approach.

Prerequisites for metallurgical consolidation are:

The powder must be fine and semi-spherical, as this allows higher packing density and low porosity, resulting in strong componentsParticles must be compositionally homogeneous as heterogeneity may comprise the benefits.

Some aerospace-relevant powder acquisition methods are known as PREP, TGA, and PA.

PREP - Plasma Rotating Electrode Process

Courtesy Erasteel


PREP employs feedstock (like the widely used aerospace Ti6-4 alloy) in the form of a rotating bar that also acts as an electrode. This is arced with gas plasma.

The molten metal is (centrifugally) flung off the bar, it cools down and is collected.

This process results in highly spherical powders, between 100 and 300 micrometers in size, with good packing characteristics, as shown on the right.

This material allows the production of high quality, near net shapes, suitable for aerospace applications.

TGA / VIM

Courtesy Erasteel


TGA is Titanium Gas Atomization, VIM is Vacuum Induction Melting.

Here, Ti is vacuum induction melted, the metal is tapped, and the molten metal stream is atomized with a stream of high pressure inert gas.

Droplet are roughly spherical and between 50 - 350 micrometers in size. Please note the material obtained is less uniform in size and shape than the PREP material.

CP (Commercially Pure) Titanium, 6-4, and other alloys, can be produced using this technology.

Plasma Atomization

Plasma atomizationprocess (source: AP&C)

SEM image of PA powder(source: AP&C)


The PA process atomizes titanium wire with 3 inert plasma jets.

The process generates highly spherical powders, with a size of around 200 micrometers maximum, as shown on the right.

The resulting material is very pure.

Again, CP, 6-4, and other alloys can be produced.

General characteristics of AMDescriptionApplicable materialsGeometries2 step process

Source: Industryweek

Source: NIST laboratories


AM is a technology to synthesize three-dimensional objects.

It is suitable for a wide range of materials, including non metallics.

Almost any shape or geometry is possible, including shapes that cannot be manufactured otherwise.

AM employs powder as feedstock.

It is a two step process, consisting of CAD modeling3D printing

CAD (Computer Aided Design) Modeling

AdvantagesFeatures


In engineering, CAD is the most widely used form of modeling.

Advantages are numerous, e.g. Automated generation of Bill of Materials Interference checking Engineering calculations (and many more)Allows rotations around 3 axes, viewing an object from any angle, even from the inside

These unique features result inLower product development costs andShortened design cycle

[Related technologies and spinoffs are CAE (computer aided engineering, FEA (Finite element analysis), CAM (Computer aided manufacturing), and others]

3D printing: general principles

A380 lightweight turbine cover door hinge (Ti64, laser sintered)

AM manufactured part vs. equivalent machined part


There are several ways to accomplish 3D printing, but they have the following in common:

1-Parts are constructed layer by layer from powdered material2-It is an iterative process, that is to say material is added bit by bit to obtain the final product.3-In contrast to more conventional manufacturing techniques like milling, material is added to obtain the final product, instead of subtracting it from billets, castings, etcetera.4-An energy source is needed to fuse the particles together.

The object on the left is an A380 part showing complex shapes can be manufactured. However, far more complex parts are also possible.

Please note the picture on the right I took at the Paris air show.

It shows two equivalent parts, having the same functionality. The left one is 3D printed while the right one is machined. The weight saved by printing is obvious.

AM - some technologiesSLM SLS DMLS EBM

Source: Monash Centre, Australia

Source: CA Models


Some aerospace-relevant AM technologies are:

Selective laser meltingSelective laser sinteringDirect metal laser sinteringElectron beam melting

SLM / SLS / DMLS

Heat source 3D CAD file basedProduction ratePioneering industries

Schematic representation


SLM, SLS and DMLS are quite similar processes.

In all cases, a laser is used as the heat source.

The main difference is that SLM achieves melting while SLS and DMLS achieve sintering.

DMLS is a further development of SLS using a more powerful laser.

A 3D CAD file is used to model the part to be produced.

The process is quite time-consuming, and therefore, it is primarily suited for smaller series. DMLS is faster due to the more powerful laser.

These technologies are pioneered in aerospace industry, and also in medical orthopedics.

EBM-Electron Beam MeltingHeat sourceFull meltingVacuum Ti suitabilityBuild rateProduct quality


EBM employs an electron beam and achieves full melting.

The beam is computer controlled and receives its data from a 3D CAD model.

The part is constructed under vacuum, which makes it a suitable technology for titanium, since Ti has a high affinity for oxygen.

The process typically uses pre-alloyed material.

The energy density is higher than with SLS, giving a higher build rate.

High quality, dense parts without porosity can be produced, allowing post process sintering to be omitted.

GE Fuel injection nozzle

GE AviationGeneral approachGeneral Electric LEAP engineWeight reductionReduction of complexityImproved durability


In aerospace, safety is of paramount importance. Consequently, when implementing new technologies, a conservative approach is needed.

When applied to the technologies discussed here, this means we tend to go from non load carrying elements to elements or structures that are statically loaded, and from there to dynamically loaded structures that may be fatigue critical.

An example of a non load carrying element is shown here.

General Electric has developed a 3D printed fuel injection nozzle for application in its LEAP engine. 19 of the nozzles are used in the combustion system of the engine.

Benefits include:About 25% lighter than its predecessor part while strongerMuch simpler design: number of parts reduced from 18 to 1.New design features, allowing more advanced cooling pathways and other improvements All this results in an estimated 5x improvement in durability.

SafetyFlammabilityExtremely sensitive to ignition from electrostatic sourcePrecautionary measuresHandlingStorageHousekeepingEmergency precautionsSource: Ming Ling Chemicals


Flammability refers to the fact the powder will burn in air if ignited.

Additionally, sensitivity to electrostatic charges is at a level that can be generated from normal operator or warehouse activities.

As a result, precautionary measures must be in place when handling the material.These include, but are not limited to:

Use of conductive flooring and footwear, personnel-grounding devices and anti-static clothing.

Powder should be stored in closed containers and these should be protected from physical damageHeat & spark generating processes like welding and grinding cannot be performed around ti powder. Smoking must be forbidden.Conventional water-based sprinkler systems cannot be used as contact of burning ti with water will generate hydrogen.

In order to prevent the accumulation of powder & dust continuous housekeeping and cleaning must be maintained.Vacuuming cannot be performed.When cleaning, vigorous sweeping and use of compressed air must be avoided as these cause formation of dust clouds.

A safe perimeter around equipment and powder must be maintained.Ti fires cannot be sprayed with water. Special extinguishing media exist and should be used instead.

Product Quality, TestingLimited availability of dataHighly anisotropicMechanical properties need to be established both parallel and perpendicular to building directionSpecimen for fracture toughness & crack growth testing (source: Edwards & Ramulu)


So far, data regarding mechanical properties of AM manufactured ti parts are not readily available, although not completely nonexistent.

In case you are interested in studies already performed, I have some literature available for you.

Due to the nature of AM, parts are highly anisotropic, requiring the establishment of properties in three directions, as shown in the image.

Currently, 3D manufactured parts cannot match the mechanical performance of conventionally manufactured counterparts. However, this may change rapidly as very much effort is being done in order to rectify this.

Costs


Titanium is expensive in its own right, it is around six times as expensive as steel. Also, Ti prices tend to fluctuate heavily.

Powder at this point in time is very expensive, in the order of 100 USD or more per kg.

Also, as the AM technologies are still maturing, these technologies are still expensive, although becoming more affordable. 3D printers are rapidly declining in price while capabilities are being improved.

As with all investments, justification of the technology is a matter of establishing a robust business case.

However, I would say that the outlook for the technology looks very promising as progress is being made to remove the drawbacks.

As a result, the technology will gain acceptance, and as TRLs improve and economies of scale apply, it is expected prices will drop.

I will now conclude with the 2 minute video, courtesy of the CSIRO institute in Melbourne.

Video (Courtesy CSIRO, Melbourne, Australia)



W: www.airbornemetals.comE: [email protected]: +31 (0)636529550

This is what I wished to share with you this afternoon.

In case would appreciate more information, please feel invited to contact me.

Thank you.

lecture ti paris rev. 1 (15:30) kopie 2

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