Titanium Grades (for your ultralight projects)

Posted: October 8th, 2014 by: h2

Ok, ok, I know, you are saying, who cares? But I was curious about titanium wire grades (for my ultralight titanium pot stands) so I found this chart here.

Element Composition,%
Grade1 Grade2 Grade3 Grade4 Grade5 Grade6 Grade7 Grade9 Grade11 Grade12
N max 0.03 0.03 0.05 0.05 0.05 0.03 0.03 0.03 0.03 0.03
C max 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08
H max 0.05 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015
Fe max 0.2 0.3 0.3 0.5 0.4 0.3 0.5 0.25 0.2 0.3
O max 0.18 0.25 0.35 0.4 0.2 0.2 0.25 0.15 0.18 0.25
Al 5.5-6.75 4.0-4.6 2.5-3.5
V 3.5-4.5 2.0-3.0

Note that lower grades are really soft, so I wanted to know what grade 5 is. Now I know.

Further, from wikipedia we learn:

Grade 1 is the most ductile and softest titanium alloy. It is a good solution for cold forming and corrosive environments. ASME SB-265 provides the standards for grade 1 titanium sheet and plate.[4]

Grade 2 Unalloyed titanium, standard oxygen.

Grade 2H Unalloyed titanium (Grade 2 with 58 ksi minimum UTS).

Grade 3 Unalloyed titanium, medium oxygen.

Grades 1-4 are unalloyed and considered commercially pure or “CP”. Generally the tensile and yield strength goes up with grade number for these “pure” grades. The difference in their physical properties is primarily due to the quantity of interstitial elements. They are used for corrosion resistance applications where cost, ease of fabrication, and welding are important.
Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the most commonly used alloy. It has a chemical composition of 6% aluminium, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium.[5] It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti).[6] Among its many advantages, it is heat treatable. This grade is an excellent combination of strength, corrosion resistance, weld and fabricability.

“This alpha-beta alloy is the workhorse alloy of the titanium industry. The alloy is fully heat treatable in section sizes up to 15mm and is used up to approximately 400°C (750°F). Since it is the most commonly used alloy – over 70% of all alloy grades melted are a sub-grade of Ti6Al4V, its uses span many aerospace airframe and engine component uses and also major non-aerospace applications in the marine, offshore and power generation industries in particular.”[7]

“Applications: Blades, discs, rings, airframes, fasteners, components. Vessels, cases, hubs, forgings. Biomedical implants.”[5]

Now I know, that’s why people use Grade 5, and that’s what I am looking for. Specifically, 0.08″/2mm titanium wire. They call it wire rather than rod when it’s thinner than about 0.125″ I believe, give or take. Anyway, for stuff of about 2mm it’s wire, no matter what the cutoff point.

Note: it’s really hard to find grade 5 2mm titanium online, but you can find it if you google for titanium bike spokes, they run about $2 each, make sure to get longer ones, most are for bmx bikes, and are too short for things like pot stands etc. 14 gauge spokes are 2mm which is about 0.08″. Spokes will be made out of very strong alloys.

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