titanium bolts and standard bolts

LightGuy · Jan 19, 2011

finnerty said: ↑

I can think of almost no "general automotive" application where using Ti-alloy fasteners is either practical or necessary. It's durability / fatigue life and fracture toughness are far less than steel alloys. So, unless you are putting them into a "one-Race-only" car / component, it is not the way to go.

The only industry that widely uses them is Aerospace. And the chief reasons are not structural or even for mass savings --- they are for thermal and electrical benefits. Ti-alloy is much less thermally and electrically conductive than steel, and it has a lesser CTE ---- these properties are often required in Aero fastener (joint) applications.
Click to expand...

I have a couple of 737 wing spar-to-fuselage 1" diameter bolts that were replaced with 1" "plus a hair" bolts as part of a mod. The replacement bolts were $1000 plus each. I gave one of the old replaced ones that were to go in the trash to my dad.
Now he knows why tickets are so much.

NW328GTS · Jan 20, 2011

I do aerospace engineering... the Ti fasteners we use are 95Ksi but we mostly use them in place of Al rivets which are about 40Ksi.

The biggest issue with Ti is you have to be cautious of galvanic corrosion. Ti needs to be plated or sealed to be used in contact with aluminum. Same with Carbon.... do not use Carbon fiber and Aluminum together without isolating them. The farther the groups are apart the worse the effect.
There are more design considerations than just strength.

From our engineering handbook:

Group Metal or Alloy:

Group I
Magnesium

Group II
Cadmium and zinc plate, galvanize, beryllium, clad aluminum
Aluminum (All alloys)

Group III
Iron, steels (except corrosion resistant steels)
Lead, tin, tin-lead solder, etc.
AISI 400 series (<14% Cr)

Group IV
Chromium plate
AISI 400 series (>14% Cr)
Copper and copper alloys (brass, bronze, etc.), silver solder
CRES (200,300,400,PH)
AISI 300 series (18% Chromium - 8% nickel)
Nickel-copper alloys (>50% nickel)
Nickel, nickel plate, monel, tungsten
Titanium
Silver, tantalum
Rhodium, graphite, carbon
Gold, platinum

The finishing of dissimilar metallic surfaces that are to be placed in intimate contact to one another by assembly requires special consideration. This is due to contact of dissimilar metals results in electrolytic couples that promote corrosion through galvanic action. To prevent galvanic corrosion in dissimilar metal joints, the following shall be accomplished in order of preference:
1. Select metals that are similar. Table above gives similar metals by group.
2. Plate with a similar metal.
3. Insulate between the metals, using sealant or organic coatings.
4. Prevent electrolyte contact by covering the junction with sealant or similar material
Click to expand...

Conversations

Alerts

titanium bolts and standard bolts

LightGuy Four Time F1 World Champ

NW328GTS Formula 3

Share This Page