poster vito esa_draft

Tensile static properties

Experimental setup Laser metal deposition setup

• Coaxial powder nozzle

• 1kW fiber laser with 1,2 mm focal spot size

• Glove box filled with argon

Sample geometry and scan strategy • Horizontal and vertical orientation

• 90 rotation of fill tracks

Post LMD • Heat treatments: 2h @ 850-950-1020C followed by furnace cooling (850C) or air cooling (950-1020C)

• Machining by electro-discharge machining or milling

Material Properties after Laser Metal Deposition of Ti6Al4V

M. Rombouts1, L. Thijs2, M. Strantza3, C. Li2, B. Vrancken2, J. Van Humbeeck2 1 Department of Materials Technology, Vito, Mol (Belgium) 2 Department of Materials Engineering, Katholieke Universiteit Leuven, Leuven (Belgium) 3 Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel, Belgium

Microstructure • No significant pick-up of oxygen, nitrogen or hydrogen during LMD (Instrumental Gas Analysis)

• Only a few small, spherical pores

• X-Ray Diffraction after LMD

• Mainly a hexagonal phase (+ bcc b in vertical oriented part)

• High crystallographic texture:

<-12-10> preferentially along build direction and <0001> // scanning directions

• Elongated prior b grains along build direction after LMD

Build direction Z Scan direction X Scan direction Y

Acknowledgement Research funded by SBO Project grant 110070: eSHM with AM of the Agency for Innovation by Science and Technology (IWT)

2h 950C, AC 2h 850C, FC

Z

Effect of machining & HT sequence Effect of loading orientation & HT

Crack growth during four point bending

Horizontal

• Relatively strong & ductile material behavior for vertical oriented part

• Heat treatments lower the strength & increase the elongation

• 850C: fine Widmanstätten α+β with discontinuous β phase; grain boundary α

• 950C: coarse Widmanstätten α+β structure with grain boundary α in columnar structure

Milling is preferred above EDM

EDM + HT: harder, more brittle surface layer (~ 440-470 HV ↔ 360 HV in centre)

Corner notch

Bottom

Side

• Crack initiation (@ 17.8 kN, 16 kN and 14.4 kN)

~ 4,5 times faster for LMD sample compared to conventional Ti6Al4V

• Crack propagation (@ 13kN)

~ 3 times faster for LMD sample compared to conventional Ti6Al4V

+ EDM HT@950C

Vertical - Top

Z