Drilling AR500 steel?

[chris in va]

I need to drill a 1/2" hole in 3/8" AR500. Someone hit it with a 50BMG and the previous hole where it met the hanger cracked right off.

Machine shop?

 

[rcmodel]

Cutting torch, plasma cutter, or another .50 BMG AP in the right place.

A carbide bit in a big drill press might drill it, but ones that big don't come cheap.

rc

 

[zerobarrier]

I tried to drill one of mine with my in-laws big ass drill press, not sure what the bit was. 5min and it barely scratched it. Ended up using a torch.

 

[Drail]

Find the idiot that shot it with a .50 cal. and have him shoot another hole in it - should be around 1/2".

 

[Blue68f100]

You may be able to anneal it with a torch. Heat it up till it's white hot and keep it that color for a few minutes. Then see if a carbide drill will work. If not just use a cutting torch to burn a hole.

 

[Zeke/PA]

I think that the "work hardening" qualities of AR500 contribute to the drilling problems.
If carbide tools don't do the job it's over.
If you do decide to try carbide, make sure that the workpiece is tightly clamped to the machine table.

 

[joem1945]

If you have a weld shop close, have them air arc a hole in it. Air arc cutting will make very short work of it.

 

[X-Rap]

Oxy Acetylene, plasma or water jet. Water is best plasma second and cutting torch last due to the heat.
Find a shop that supplies to the mining/milling industry, they cut and bevel holes in wear plate for chute and conveyor hoppers all the time.

 

[Darkbob]

I don't know if it's true but I've read that if you try to cut it or weld it with anything that uses heat the heat will destroy the hardening. So if you do cut it with a torch, be prepared to have softer steel near the hole unless you have a way of hardening it to AR550 specs again.

 

[jmorris]

As above water jet or laser is best, carbide will do it too but slow. Plasma won't hurt it as much as Oxy/Act because it requires no pre heat.

 

[vongh]

Send it to me. I'll poke a hole in it.

 

[Red Cent]

I would bet the 50 cal did not make a hole.

 

[Dan Forrester]

Just weld a piece of chain on it. Sounds like it's already messed up anyway.

Dan

 

[sfed]

Welding anything to AR plate requires the plate to be preheated for the weld to hold, if not preheated the chain or whatever is welded to it will pop off with a shock load and the weld will pull off a thin layer of the AR plate. The plate will need to be preheated to a minimum of 400F in an area of 2 to 3 inches around the intended attachment point for it to be actually welded to the plate. I have fabricated many things out of AR plate and found out the hard way about welding to this material, in welding pad eyes to AR plate for lifting with a hoist to put into position I have seen these pad eyes pop off from having been welded to the AR plate without proper preheating. I suggest just cutting a hole with a plasma or a torch, you will have a much better attachment point doing it that way.

 

[joem1945]

A500 steel swinger out a 150 yds got hit so many times it broke apart with a entirely crystallized structure.

 

[chris in va]

Looks like the square hole wasn't properly chamfered. When the 50 hit it, must have cracked it right off.