AcceptLearn

Structure: 1. General Titanium & Titanium alloy knowledge 2. ExpaniteHard-Ti Fighting wear and corrosion on stainless steel and titanium Accept …And remember First - A closer look at Titanium Allotropic crystal structure

“Soft one” “Hard one” Extremely generalized

a (HCP) 882.5°C b (BCC) Learn First - A closer look at Titanium Classification and general properties:

Commercially pure (CP) titanium, alpha and near alpha titanium alloys - Generally non-heat treatable and weldable - Medium strength, good creep strength, good corrosion resistance

Alpha-beta titanium alloys - Heat treatable, good forming properties - Medium to high strength, good creep strength

Beta titanium alloys - Heat treatable - Readily formable (in solution treated condition) - Very high strength, low ductility Learn First - A closer look at Titanium Classification and general properties:

Alpha stabilizers: Al, Sn, O & N

a a+b b Beta stabilizers: V, Mo, Cr, Cu, W, Nb. Learn First - A closer look at Titanium Classification and general properties:

a - stabilized phase diagram

Alpha stabilizers: Al, Sn, O & N Pure titanium 882.5°C a a+b b Beta stabilizers: V, Mo, Cr, Cu, W, Nb. Degree of alloying elements Accept First - A closer look at Titanium a Heat treatment

Annealing at 700C produces a-phase

Quenching from the b phase field results in a martensitic transformation, i.e. b is converted to HCP-a’ (with some retained b)

Air cooling from the b phase field results in a so- called Widmanstätten structure of a-plates Accept First - A closer look at Titanium Near-a Heat treatment

The alloy is heated up to the b region

• Air-cooling gives Widmanstätten α structure with some b • Quenching gives transformation of b to lath α’ with some b; ageing results in precipitation of α.

Quenched (a’+b) Quenched & aged at 850°C Aircooled (Widenstätten+b) Learn First - A closer look at Titanium a + b Heat treatment

Alpha-beta titanium alloys contain both α and β.

α stabilizers (4-6%) are used to give strength β stabilizers to allow the β phase to be retained at RT after quenching from β or α+β phase field.

Improved strength and formability in comparison to α -Ti alloys.

Ti-6Al-4V (Grade 5) is the most commonly used alloy. Accept First - A closer look at Titanium a + b Heat treatment

Topics in the following:

• Cooling from the b and a+ b phase fields

• Quenching from from the b and a+ b phase fields • Above and below Ms Accept First - A closer look at Titanium a + b Heat treatment Slow cooling from β (1060C-beta annealed) Slow cooling from the α+β phase field (950C) Transformation from β to α microstructure containing a Near- equilibrium microstructure with lamellar structure (similar crystal orientation). equiaxed primary α phase surrounded by retained β phase.

Ti-6Al-4V - Annealed from β phase field; transformed β phase or Annealed from α+β phase field, showing equiaxed α grains lamellar(basket weaves) microstructure. (light) with intergranular retained beta (dark) Accept First - A closer look at Titanium a + b Heat treatment Intermediate cooling from β (1060C-beta Intermediate cooling from the α+β phase field annealed) (950C) From the β phase field produces fine acicular α, which is From the α+β phase field results in equiaxed primary α transformed from the β phase phase in a matrix of transformed β phase (acicular). Accept First - A closer look at Titanium a + b Heat treatment

Quenching from b – martensite formation

Ti-6Al-4V alloy solution-heat-treated at a’ lath a’ lenticular a’’ (orthorhombic) 1066°C/30min and water quenched

Increasing solute Accept First - A closer look at Titanium a + b Heat treatment Quenching from a+b phase field Below b transus and above Ms (950C) Below Ms (850C) Microstructure consists of primary α Microstructure consists of primary α phase phase and small amount of retained embedded in transformed β phase (α’ or untransformed β. martensite).

Ti-6Al-4V alloy solution-heat-treated Ti-6Al-4V alloy solution-heat-treated at at 954°C and water quenched 843°C and water quenched Learn First - A closer look at Titanium b General knowledge Beta stabilizers ensure a fully β structure (no martensite formation) when quenched from the β phase field

Metastable β alloys : Mo Eq. <25 Stable β alloys : Mo Eq. 25-40. Learn First - A closer look at Titanium Heat treatment b β titanium alloys have a BCC crystal structure, which is readily cold-worked in the β phase field.

Quenching results in an equiaxed β phase.

Solution heat treating + quenching give very high strength (up to 1300-1400 MPa).

Metastable β Ti alloys are hardenable while stable β Ti alloys are non- Ti-13V-11Cr-3Al alloy solution heat-treated at 788oC/30min and water-quenched hardenable Accept First - A closer look at Titanium b Heat treatment

Most β titanium alloys are metastable and tend to transform into

(1) coarse α platets after heat- treatment in the α+β phase field or

β annealed microstructure, β CEZ (Ti-5Al-2Sn-2Cr-4Mo-4Zr)- beta rich (2) α phase precipitation after long term ageing at elevated temperature (gives higher strength but can cause embrittlement)

Effect of pre-aging on microstructure of heavily stabilized β alloys Beta 21S (Ti-15Mo-2.6Nb-3Al-0.2Si) Product portfolio – a closer look at ExpaniteHard-Ti

ExpaniteHard-Ti ExpaniteHard-Ti • Gas process <800C • Surface hardness: approx. 1000HV • Adds oxygen; no titanium-nitrides • Case depth: 10-50µm • Can be used for: • Alloyed titanium e.g. grade 5, 23 • CP titanium e.g. grade 2 ExpaniteHard-Ti ExpaniteHard-Ti 3D printed titanium

Things to consider:

• Heat treatment condition & microstructure before and after hardening. • Post-hardening machining • Porosity! ExpaniteHard-Ti 3D printed titanium • Porosity! As- printed Printed and grinded

NOT TITANIUM Principle is the same Applications: Watch in titanium

• What: all exterior parts (case, bezel, bracelet, back, buckle) from Swiss watch brand Horage • Part are made in titanium grade 5 and then hardened by Expanite (ExpaniteHard-Ti); 30µm and approx. 1000HV. • Benefits: • Unique product with virtually unscratchable surface!

Whats next? • Upcoming Webinars • Oct 29, 9:00am EST: ExpaniteHard-Ti – Hardening of TITANIUM (EN) • Oct 28, 9:00am : Surface hardening of stainless steel

• Stay in contact • Rune Bielefeldt Strand • [email protected] • Note: I’m not available in November… So hurry up with questions.

www.expanite.com Expanite A/S http://www.linkedin.com/company/expanite-a-s/