Have been forging a few things from recycled aircraft engine head bolts like the one at the bottom of the picture.  I'm not sure what sort of steel it is (any ideas?) but it's hard and takes a very high polish. It works quite well. I think it would be tool steel of some kind so I don't quench it from forge heat as it may become brittle. A couple of questions: Would it be necessary to temper the meat forks or would just air cooling be sufficient? And what about the finish? It seems that the metal keeps its shine without lacquer or wax coating.  I think these bolts would make pretty reasonable knives too, not sure.

I have a mate who is an aircraft engineer and he supplies me with heaps of these bolts. Any other ideas for their use, or any issues with the steel??

Neat , liked how you incorporated the machined section in the center.

Probably 4340. Most aircraft hardware is made for toughness. Better to bend than break and they rely on lots of smaller bolts than 1 or 2 big bolts for redundancy.

Hmmm, have you spark tested any of these? I wonder if they may be a stainless alloy. 

I would test the corrosion resistance of the bolts (studs?) which would tell you something about their potential uses, even if you don't determine the exact alloy. They might make good stock for outdoor fixtures or cooking utensils.

I have seen several kinds of steel, Inconel (usually 718), and Ti-6Al-4V bolts used in aircraft engines. I say try a spark test as BGD suggests. 

As for the steels, many were 180-220 ksi (and sometimes allowed for bolts from a list of compositions heat treated accordingly), but sometimes more or less. If you end up with a cut off from one of your projects, a quench test could be revealing. 

Thanks. Lots of offcuts so I will do a quench test and see what happens. I'm not sure what to look for in a spark test, but I'll compare it with mild and see what it does. The bottle openers sell well - I think people like the idea of repurposed stuff.

The idea on the spark test is to have a number of different samples of KNOWN alloys and then do 1:1 comparisons until you find one that looks similar.

20 hours ago, ThomasPowers said:

The idea on the spark test is to have a number of different samples of KNOWN alloys and then do 1:1 comparisons until you find one that looks similar.

Known is the operant word. I guess we all have heaps of different steels and no idea what they are. The sparks off this steel look exactly the same as mild steel sparks to me. And I heated a piece to cherry red and quenched it in cold water. I thought it would be brittle but I couldn't break it with a three pound hammer in the vice. Tough stuff.

On 8/16/2016 at 6:42 PM, ausfire said:

I have a mate who is an aircraft engineer and he supplies me with heaps of these bolts. Any other ideas for their use, or any issues with the steel??

Ausfire, it looks like a crankcase through-bolt from a small aircraft engine. I don't know what specific alloy it is, or if different alloys were used for through-bolts for different engines or by different manufacturers, but perhaps you could contact a manufacturer and narrow it down. Here's an example of something similar.

http://www.aircraft-specialties.com/thru-bolt-1-2-20unf-x-10-75-long-sa641931-10-75/

23 hours ago, Steamboat said:

Ausfire, it looks like a crankcase through-bolt from a small aircraft engine. I don't know what specific alloy it is, or if different alloys were used for through-bolts for different engines or by different manufacturers, but perhaps you could contact a manufacturer and narrow it down. Here's an example of something similar.

http://www.aircraft-specialties.com/thru-bolt-1-2-20unf-x-10-75-long-sa641931-10-75/

That's it all right. I didn''t know they are called thru-bolts. Thanks.

2 hours ago, ausfire said:

That's it all right. I didn''t know they are called thru-bolts. Thanks.

"Thru-bolt" is probably an alternate way of spelling "through-bolt." The latter should produce more search results. Good luck determining the alloy.

Are they thru-bolts, or studs?

When you spark test them have a picture taken of them. If they are bright white they are probably titanium - they will also feel light for their size.. 

1 hour ago, BIGGUNDOCTOR said:

Are they thru-bolts, or studs?

The ones I've seen use a nut on both ends, and I've seen them called out as "through bolts" in aircraft engine overhaul manuals.

11 hours ago, Steamboat said:

The ones I've seen use a nut on both ends, and I've seen them called out as "through bolts" in aircraft engine overhaul manuals.

These had nuts on both ends. Sparks are orange - same as mild.