titanium bolts and standard bolts

Don't know but they are not as strong so you will need to go to much bigger fasteners to do the same job.

 

I think if you're building multi-million dollar aircraft or an ultra high revving race engine where every gram of reciprocating mass is important it can pay off. On a street-driven car, not so much.

 

Not stronger......weaker. Common misconception.


Think of Ti as the middle metal. Between aluminum and steel only more expensive.

Lighter and softer than steel. Heavier and stronger than aluminum.

Ti bolts are almost never used.

 

I believe they are 45% lighter.
The sprint car guys I built engines for (when there was no minimum weight limit) used them on every non-critical/highly stressed part on the car. They even started using rifle-drilled titanium bolts to save weight.

More info :
http://www.differencebetween.net/object/difference-between-steel-and-titanium/

 

You may be referring to the Challenge lug bolts?

They are very very cool, and worth having just for the coolness factor. But don't expect any performance increase.

If anyone can detect the weight difference between Ti and steel, using seat of the pants or a stopwatch, then you MUST quit your day job.

Tell your boss to bugger off. You then need to go directly to the nearest airport. Go thorough the door that says "International Flights". Spend your last bit of money on a one way ticket to Italy. When you get out of the airport in Bologna, grab a taxi. They are crappy orange Fiats over there. Ask him to bring you to the place where they test the Ferraris. He will know how to get there. Walk up to the front door and knock twice. When the guard answers, tell him "I'm here".

"Who are you?"

"I'm the guy who can tell the difference with titanium lug bolts"

"Aaaah yes. We have long been waiting for you.
Please, come in."

 

Funny, I usually got a nice clean Opel with a driver who was a frustrated, under appreciated as yet undiscovered F1 Piloto.


Other than that....all true.

 

Just a tip from a know-it-all, smart-a** physics student:

The next time you get an idea like this, grab a napkin or an envelope and do a quick calculation.

Divide the planned weight reduction by the overall weight of the component... in this case, the weight of the bolts vs. the weight of the tire / wheel / bolts / rotor combination. If your result is less than 10%, even less than 20%, it's doubtful you'll notice anything.

I can give you the formulas to make a better approximation for things like bolt changes / tire changes / wheel weights, but you'll likely come to the same conclusion.

 

Bologna? Come on boys! Fly into Milan and learn to drive like a proper Italian in a rental Fiat Punto. Half the roads are mislabeled, half the roads are unlabeled, and the final half of the roads are alleys.

 

Engnfxr is correct, ti weights about 56% of steel (45% less), and Brian is sorta right in that it isn't as quite as strong as a high strength steel like 4130, but compared to quenched and tempered 4130 (ultimate 180ksi, yield of 165ksi) Ti 6-4 is almost as strong (160 ksi ultimate and 145ksi yield). So the strength to weight ratio is more than 50% better. That is, the strength to weight ratio of steel is 600ksi/lb and titanium is 941ksi/lb. You can harden steels to be stronger, but they tend to become brittle as you do.

There are also other issues with using titanium in that you can get thread galling and that can make it impossible to take things apart, so it isn't commonly used for fasteners outside of the aerospace industry.

Where titanium shines is in rotating or reciprocating parts like valves or connecting rods, or compressor wheels, where the mass of the part is a big factor in the the loading. So long as you don't get it too hot, titanium is good stuff. As with any material, it has its limitations and using it where it doesn't make sense is just throwing money away, and lug nuts are probably a good example of that.

Then again, Chapman put aluminum lug nuts on the 1974 Lotus Elite to save a few ounces....

 

If you still had your 348 you wouldn't be worrying about losing weight!!! Ahahahaha!

Or buy a 308QV like me!

MB

 

Titanium does have advantages in high heat applications at relatively light weight, like SR-71 wing leading edges and reentry vehicle thermal protection systems, with a melting point of 3040 deg F compared to aluminum at 1220 and stainless steel at 2750. But ceramics are replacing titanium in many of those applications. Last I heard nobody had melted a set of SS lug bolts. They do lower unsprung mass marginally, but their location close to the center of the wheel does virtually nothing for rotating mass. Not exactly a high pay-off application, but maybe a bit of gee whiz factor, if that is important to someone. Titanium makes much more sense in a rotating or reciprocating application.

Taz
Terry Phillips

 

This should set the record straight: All this data comes from MIL-HDBK-5, Metallic Materials and Elements for Aerospace Vehicle Structures, which is THE BIBLE for this type stuff.

Typical Mil-Spec AN Series Bolt. (Which holds together 99.9% of planes, racecars, etc. together)

Ultimate Tensile Strength: 120,000-125,000 lbs/in^2. This is also close to an SAE Grade 5 or Metric 8.8/9.8 Grade bolt.

Typical SAE Grade 8 Series Bolt

Ultimate Tensile Strength: 150,000 lbs/in^2. This is also close to a Metric 10.9 Grade bolt.

Typical MS2000/NAS 6xx Series Series Bolt:

Ultimate Tensile Strength: 180,000 lbs/in^2. This is also close to a Metric 12.9 grade bolt.

Titanium Bolts

6AL/4v Alloy

Ultimate Tensile Strength: 120,000-125,000 lbs/in^2

Ti-15/3/3/3

Ultimate Tensile Strength: 150,000 lbs/in^2 (Temper of 1000°F-8 Hours)

Ultimate Tensile Strength: 175,00-185,000 lbs/in^2 (Temper varies)

So you can get a Ti bolt in exactly the same strength range as most (95%+?) steel bolts.

BUT there are many other factors to look at when choosing a bolt than ultimate tensile strength. (Usually UTS alone is not #1 on the requirements list!)

 

Great info Brian.

 

While it has a pretty good melting temperature, you almost never use titanium above 800 degrees F because of stress corrosion issues and all of my titanium material property curves end at 1,000 degrees F because that is the aging temperature and the strength up there is in the toilet. At 800 degrees the strength is about 75% of room temp strength and at 1,000 degrees it is about half. It can be used for things like exhaust systems provided it isn't wrapped to trap the heat, but it's best used below 750 F.

Titanium can burn if rub it against titanium in a high pressure atmosphere. It burns really hot, and once lit it isn't going out any time soon.. Been there, seen that, wasn't pretty.

 

So does aluminum--just ask the crew of the HMS Shefield.

 

To answer your actual question ---

The most common (typical) Titanium alloy used for fasteners is [ Ti6Al4V ], and it weighs about 40% less than structural steel.

However ---

I would not recommend it for your application (general purpose automobile fasteners). Its (Ti alloy) properties have more disadvantages than advantages for that use.

 

Yes.

No.

Yes --- considerably.

 

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.

 

Higher strength (up to 400 kpsi) CRES steel alloys are used typically (for Aerospace fasteners) --- there's also the issue of maximum allowable strain

 

I love it.