Ti vs. Alloy Bolts - Telling Them Apart

[DHallerman]

I recently got an older Serotta ti quill stem (thanks Aaron), and when taking it apart to clean it, I realized the two bolts are certainly not steel.

That's easy, says the man who owns a magnet.

But are the bolts also ti? Or might they be alloy?

I'm asking both for this stem, specifically, but in general: How can you tell if bolts (or perhaps other parts) are made of titanium or aluminum alloy?

Dave, who will use anti-seize anyway to lube these two bolts but would still find it useful to know and might replace the clamp bolt with steel anyway

[weiwentg]

no sane person would put alloy bolts on a stem. it's very likely that they're ti. I know that doesn't actually help you to tell, but I'd feel safe making that assumption.

[David Kirk]

The Serotta quill stem used a Ti wedge bolt and a stainless handlebar clamp bolt. Neither will stick to a magnet.

Dave

[DHallerman]

Thanks for the backstory, Dave.

You know, I've heard that stainless steel doesn't stick to a magnet.

However, I have this pretty powerful magnet in my shop, and I know it will stick to the stainless spindle on a Phil Wood bottom bracket.

(But it doesn't stick to this stem's clamp bolt.)

So, is the stainless-magnet-not-stick absolute? Or, does it depend on the make-up of the stainless?

Dave, who often thinks a bare stainless steel looks better than bare titanium

====================

The Serotta quill stem used a Ti wedge bolt and a stainless handlebar clamp bolt. Neither will stick to a magnet.

Dave

[David Kirk]

The alloys of stainless vary and some are magnetically attractive and some not. So no it not absolute.

Ti never sticks regardless of the alloy.

dave

[Dave]

Aluminum bolts are usually a white-silver color and Ti bolts usually look grey, but could be slightly golden, much like stainless steel.

As noted, some stainless steel alloys are magnetic and some are not, so a magnet test is not the answer.

[csm]

aluminum bolts will strip very easily whereas ti and steel won't.
so......
if you strip a bolt... it most likely is aluminum.