AR 500 Steel

[bodiedyota92]

So i am going to cut some targets for a local gun range w/ my plasmacam and Hypertherm 45. The plate is 3/8". Any tips tricks or suggestions. All is greatly appreciated. I can not afford to mess up this plate. Thanks in advance.

Chris

[plain ol Bill]

Chris it will cut just like it is A36 mild steel plate. Follow the Hypertherm guidelines for your machine and you will be fine.

[I Lean]

I deviate just a little bit on 3/8" with my PM45...increase the pierce height. Instead of the .15" they recommend, I go .22". I feel it decreases the slag blowback that gets on the nozzle, or between the nozzle and shield--leading to longer consumable life.

[bodiedyota92]

Thanks guys. Ill give that a shot and let ya know how it goes...

[jimcolt]

AR plate cuts fine using book specs. The plasma is not affected by the hardness of the material.

Jim Colt Hypertherm

[littlefatbuddy]

I cut some holes in 3/8 AR500 last week. I am running a pm65. It cut no problem with book specs. However, I do not recommend using a $40 Greenlee step bit to knock of the edges. It didn't even bind up and snapped it in half. It was only the second time I had used the bit so I knew it wasn't wore out. I probably should have known better.

[bodiedyota92]

Thanks for all the input. I cut some targets and it didnt go to well.. It would pierce fine and start cutting fine. But then it was like slag or dross would pile up around the torch head and not cut all the way through. Any suggestions. I dont know much about AR steel. But it had a brownish type of coating on it. The guy who bought got it second hand from a range that was closing. But it was not shot up. It was used for ricochet protection. Thanks
Chris

[kkroger]

What settings are you using? Cut Speed? Current?
THC or no?

My 65 will walk through 3/8" like butter...
Not sure on the 45...

[weldor2005]

I'm getting a plate of it to cut some targets as well. Seems terribly hard to source. Its like, I know a guy who knew a guy who called someone to get me a plate. and then ship it 250 miles. still even after shipping it comes to $600. Cutting it for friends (You never know when you will want these kind of friends.), so we get great targets at an affordable at cost deal. The cost of the plate 4x8 was $417. I think steel has been going down slightly. I just got 4x8x 10ga A36 for $100/sheet.

I also will be using plasmacam and Hypertherm Powermax 45 BTW.

[littlefatbuddy]

Teinart Metals in Lubbock, Texas stocks AR500. They will ship I believe. I would be interested in getting Jim's opinion on plasma vs. laser for cutting the AR500 and how it affects the "hardness" around the edges.

[weldor2005]

Teinart Metals in Lubbock, Texas stocks AR500. They will ship I believe. I would be interested in getting Jim's opinion on plasma vs. laser for cutting the AR500 and how it affects the "hardness" around the edges.

I know you wont take my word for it as you don't know me. But having a background as a welding engineer and some metallurgy, it is negligible to the point that I have no concerns. It gets plasma cut and welded all the time for AR plate applications like dump truck bodies.

Besides you are not supposed to shoot the edge of the target.

[jimcolt]

Plasma will actually soften the edge slightly on AR plate....usually in an area less than .010" from the cut edge. Laser will have a hard time with AR500, but if it does cut ok the softening will be less than with plasma. Waterjet will be the slowest, most costly, most accurate cutting process on AR plate...and with no effect on the base hardness.

AR plate for targets is almost always cut with plasma. The cut specs, piercing specs, power levels are generally the same as with standard mild steel. If you want superior edges and minimal heat affected zone use a high definition class plasma with oxygen as the plasma gas and air as the shield gas.....as opposed to an air plasma.

Jim Colt

Teinart Metals in Lubbock, Texas stocks AR500. They will ship I believe. I would be interested in getting Jim's opinion on plasma vs. laser for cutting the AR500 and how it affects the "hardness" around the edges.

[weldor2005]

Of course I don't have any pictures on the computer at this point, but there will be a video I will share of this process eventually. Cutting the 3/8" AR500 at book specs for Mild Steel with the PowerMax45 gave me what I would call okay results. It cut 99% of my first 4x4 section no problem, other than a heavy dross on the bottom, but that chips off to reveal the same cut profile that I have come to expect from A36. Of course the majority of my cutting was on circles and looking at the lines of the arc left on the steel it seemed that it may have actually been a tad fast, however there was no evidence of this other than that 1% that didn't get all the way through. Literally about 1/2" out of 830" of cut and around 50 pierces. If I am to make a habit of cutting it, I would try to adjust for it, but really for doing a plate maybe once a year if that, I am happy with the results. The smallest holes I got in this nest was 1/2", and although not very round as its height control had to jump over the dross from the pierce, the punched out with a hit from a hammer and a punch no problem.

As for what happens to the hardness of the edge. To explain it a little more, since AR500 is a Q&T steel, when thermo cutting it, the immediate kerf sure is pasted the AC1 temperature of the steel (AC1 is when the crystal structure starts to move again) so that would then get what is effectively an air quench treatment and that is enough to slightly harden the steel, but not as much as a rapid quench that it normally receives would provide. Then for the steel away from the kerf, (As Jim mentioned, .010") is sees temperatures that may have been higher than the temperature used to temper the steel initially and this would cause slight softening. Then as we move even further from the kerf, the temperature doesn't approach the original tempering temperature, and will not affect the steel at all unless is is held at temperature for an extended period of time, which is measured in hours minimum, and thus the time on the cutting table wouldn't effect it.

Maybe this little dip into the metallurgy of what the thermo process of plasma cutting AR500 plate does has helped some of you.

Again, look for me uploading some pictures and a video link sometime soon.

Thank You,

[weldor2005]

I figured I would just keep this all in one thread and not bother with starting another. Here are some of the results as I posted about. For the second half of the sheet I turned the speed down from book specs because I had a spot that gouged rather than cut. In haste, I think I turned it down too much, from 32 to 22, but I did so while cutting, and it cut the remainder of the sheet fine like this (With no improvement on the heavy dross). The sheet sitting on my fixture table is the half inch one yet to be cut. One thing I did notice about the slower speed, was I didn't have to punch out so many of the holes, they dropped out on their own. Either way I got good quality edges from both speeds in my mind.

I feel that the quality of cut was good on book specs, I just noticed it hiccuped on a spot where it was going around a circle and then through some grating and it didn't recover past the grating, so I slowed it down some.

Hope all this information helps.

Heavy Dross Left On Them

Some of the Cuts

Some More of the Cuts

Angularity of Cut

Cut Quality

1/2" AR500 waiting to be cut.

[weldor2005]

Oh yea, those holes that didn't want to fall out, punched out with a hammer and this home made punch.

Punching Holes

[jimcolt]

The 45 amp shielded process is rated for a maximum production cut on 1/2" steel. At the max rating for a Hypertherm, expect the dross free speed zone to be very narrow. If the book says 32 ipm, you often can get a dross free cut....unless there are alloys in the plate (higher carbon, silicon, manganese) that are harder to cut without dross.

At 22 ipm on 1/2"....at 45 amps, I would expect heavy dross as you are showing in the pics. When I used to use the Powermax45 on my cnc machine I cut 1/2" at 28 ipm, usually with little or no dross. Here are my 1/2" as cut pieces at 28 ipm, 45 amps shielded, ,06" cut height. The holes were cut about .035" oversize and at 60% speed, 1/2" bolts drop through. This is standard grade (A36) mild steel, the AR plate will have a different result (of course!)
Jim Colt

IMG_2948.jpg (51.09 KiB) Viewed 2343 times

I figured I would just keep this all in one thread and not bother with starting another. Here are some of the results as I posted about. For the second half of the sheet I turned the speed down from book specs because I had a spot that gouged rather than cut. In haste, I think I turned it down too much, from 32 to 22, but I did so while cutting, and it cut the remainder of the sheet fine like this (With no improvement on the heavy dross). The sheet sitting on my fixture table is the half inch one yet to be cut. One thing I did notice about the slower speed, was I didn't have to punch out so many of the holes, they dropped out on their own. Either way I got good quality edges from both speeds in my mind.

I feel that the quality of cut was good on book specs, I just noticed it hiccuped on a spot where it was going around a circle and then through some grating and it didn't recover past the grating, so I slowed it down some.

Hope all this information helps.

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[weldor2005]

I haven't cut the 1/2" yet, but plan on doing so today. I know when I cut the A36 3/8" at book specs, it was dross free. I completely understand with alloyed plates that it is likely to be a slightly different outcome. I over sized my holes by .062 and they drop a 5/8 as requested by some of the customers on these. Will be looking forward to getting this next set cut on 1/2"

[littlefatbuddy]

The targets look good. It looks like the dross chipped off relatively easy? I really appreciate all the feedback on how plasma affects the hardness. David, I have no reason not to believe you. You are certainly right that we aren't supposed to shoot the edges, however I am not much better at shooting than I am plasma cutting. I "shoot" for the best and hope I don't get the worst. It was all great information and I truly appreciate it. Sorry for semi hijacking your thread.

[weldor2005]

The targets look good. It looks like the dross chipped off relatively easy? I really appreciate all the feedback on how plasma affects the hardness. David, I have no reason not to believe you. You are certainly right that we aren't supposed to shoot the edges, however I am not much better at shooting than I am plasma cutting. I "shoot" for the best and hope I don't get the worst. It was all great information and I truly appreciate it. Sorry for semi hijacking your thread.

Ha, that is alright, these forums are for learning after all. Can't learn if people wont share, I just share more information than files it seems since I'm not the creative type. I can program shapes like you wouldn't believe, but coming up with nice catchy items isn't my forte. Plus, it wasn't my thread, I hijacked it from bodiedyota92. And I hear ya on shooting, I got some cut for my own practice with my pistols as well. Not concerned about shotguns and rifles, but pistols need practice.

Yes, the dross came off with just barely using a cold chisel. Some of the holes needed a little more persuading, but that was because of my inferior programming skills. With the plasma arc being at the 30° angle on the kerf, when I got to the finish there simply wasn't enough over cutting programmed in. I got to say for those that are hesitant to fork up the cost of the plate because of the unknown in how it will cut, not to worry about that part, it really is like A36 in most regards. That being said, I would still do a test cut first in a small portion of a drop or one of the smaller parts.

Finally, I would also like to add one more little item of information on the heat input. Seeing as I am using a PM45, and it needs a slow cut speed, it is inputting maximum heat into the part compared to a higher amp machine that would move faster and put less heat into it. That being said, I used temp sticks when cutting the 1/2" plate, and found that if I mark a line ahead of the cut, 300°F will melt as it gets cut, but a few inches behind the cut 300°F will not and 250°F will. About 12" past the cut, 250°F wouldn't melt, but 200°F would. Marking a 1100°F line in front of the cut, and as expected, it didn't melt. My range of temp sticks was limited and I didn't have any between 300°F - 1100°F, I am sorry or I would have done further testing.

I know I am showing kind of a oops cut, but it will function, and this is all I have on my phone for pictures. Again, a video of my cutting will be done eventually and I will post a link to it here.

During Cutting 1/2" AR 500

12" Round 1/2" AR 500

[Kenlove]

My intro to CNC plasma started with cutting ar500 I use a shopsaber table with an 85amp hypertherm with no issues I cut 3/8 at 65 amps @ 65-70 ipm without issue I run he water at the bottom of the plate to keep things cool. I have built the baffle and trap systems at two indoor ranges one of which had a rifle range that I am sure all the amateur rifle shooters in Texas shoot at (because they have hit my baffles thousands of times) with everything up to 338 lapua. Go ahead and cut it then shoot away I can assure you plasma had no identifiable effect on ar500. I have cut about 150000 pounds of ar500 in the last two years it cuts about the same as mild steel you may have to do a little playing around with your machine to get good cut quality but it shouldn't be an issue

[I Lean]

Just for your future playing-around, I've had good luck piercing 1/2" AR500 with my Powermax 45. I know it's thicker than it's rated for, but it'll do it. Takes a while though--I use a 2 second pierce delay, and a .24" pierce height. (info for if you want to eliminate all the edge starts, and the slits leading to the chain holes)

I do use edge starts where I can, and chain cutting also--but if I can't, then pierce it.

[weldor2005]

Just for your future playing-around, I've had good luck piercing 1/2" AR500 with my Powermax 45. I know it's thicker than it's rated for, but it'll do it. Takes a while though--I use a 2 second pierce delay, and a .24" pierce height. (info for if you want to eliminate all the edge starts, and the slits leading to the chain holes)

I do use edge starts where I can, and chain cutting also--but if I can't, then pierce it.

I will have to give that a try, are you doing anything different with your cut speed?

[I Lean]

I will have to give that a try, are you doing anything different with your cut speed?

Nothing special. From memory, I think it's around 18-20 IPM. Most likely pretty close to book spec, or just a bit slower.