Welding AR plate ?

[DIBBS]

I had a friend weld together several pieces of AR plate with a wire feed welder, so that I had a target size that better matched+ my current abilities @ 600+ yards. He just tacked the seams for 2" on the edges and in the center, and unfortunately the target only lasted for half a dozen shots with a .308 win before it broke. Any suggestions on how to weld the 10" AR square plates together so that they will hold, and also not lose their temper? Do they need to be attached to a backing plate? Thanks for your suggestions.

 

[Wicked Weapons]

Re: Welding AR plate ?

AR plate is not unweldable, but its best not to though. The heat affected zone next to a weld or hot cut will not be as strong as the plate. Anywhere it's been torch/plasma cut or welded by any method will be annealed and somewhat softer than the rest of the plate. It can be joined by welding, but there are limitations. They should be a full penetration and full seam welds. Standard MIG welding wires (ER70S) just don't have the tensile strength required. One suggestion is 307SS filler with plenty of pre-heat and use a pulsed MIG machine.

The best solution is just to find a single piece that's the size you require.

 

[banks74]

Re: Welding AR plate ?

I have never welded 2 plates together, but I have attached bolts to AR plates. I used some preheat/postheat and a low hyd. rod like 7018. Definitely softer around the heat affected zone, but still withstands rounds way better than mild steel.

 

[KE5MUJ]

Re: Welding AR plate ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: banks74</div><div class="ubbcode-body">I have never welded 2 plates together, but I have attached bolts to AR plates. I used some preheat/postheat and a low hyd. rod like 7018. Definitely softer around the heat affected zone, but still withstands rounds way better than mild steel. </div></div>

I was wondering how well AR plates took with 7018 rods. I know stick welding will have better penetration than mig.

So, you think pre and post heating is crucial?

 

[SND]

Re: Welding AR plate ?

Mechanically cleaning the weld joint [remove mill scale and rust to bright, shiny metal] and about an inch from the expected weld toes and keeping the heat input [HI Joules= Voltage*amperage*60/TS in IPM)at 35000 to 40000 joules to manage the cooling rate is much more inportant than preheat. Too quick a cooling rate and you end up with embrittled HAZ, too slow and you get excessive softening. Only preheat I'd do is enough to run the moisture out of the plate. Make sure your E7018 is dry.

AR500 has a 250 KSI tensile last I checked so there's no way your E7018 weld metal will be as strong as the base material. You're looking for soundness only. <span style="font-weight: bold">For targets, I don't think any of this is a huge issue ...</span>

 

[banks74]

Re: Welding AR plate ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: trigger happy</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: banks74</div><div class="ubbcode-body">I have never welded 2 plates together, but I have attached bolts to AR plates. I used some preheat/postheat and a low hyd. rod like 7018. Definitely softer around the heat affected zone, but still withstands rounds way better than mild steel. </div></div>

I was wondering how well AR plates took with 7018 rods. I know stick welding will have better penetration than mig.

So, you think pre and post heating is crucial? </div></div>

I honestly do not know if it is crucial or not. I asked one of my welding instructors how to approach AR plate. They said they personally did not have a lot of experience with it, but they told me when they did weld Ar on occasion they did use preheat and more importantly post heat.

7018 seems to run pretty well on AR so far.

 

[KYS]

Re: Welding AR plate ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: dibbs</div><div class="ubbcode-body">I had a friend weld together several pieces of AR plate with a wire feed welder, so that I had a target size that better matched+ my current abilities @ 600+ yards. He just tacked the seams for 2" on the edges and in the center, and unfortunately the target only lasted for half a dozen shots with a .308 win before it broke. Any suggestions on how to weld the 10" AR square plates together so that they will hold, and also not lose their temper? Do they need to be attached to a backing plate? Thanks for your suggestions. </div></div>

Save yourself the headache and get yourself a new piece made. There are plenty of guys here on the hide that offer custom targets in AR500 steel. I have seen some guys working with AR500 and it does not weld easily. You really have to know your welding tech to successfully make it work and be strong. I always buy my targets from OSUARCHITECT @ Big Dog Steel. His work is top notch.

 

[Malibumick]

Re: Welding AR plate ?

Send Outback a PM, He will know what to tell ya or even sell you a target. He does know his stuff when it comes to welding!


Mick

 

[caustic]

Re: Welding AR plate ?

SND has it right, clean the weld area, you can use the rod or wire as preheat by starting with a weld tab, you do NOT need a high tensile strength rod (for what you’re doing) to weld AR. what happens to most is that the AR over hardens and breaks a chunk off from under the weld zone, there are way to stress relieve the weld area like post heat and slow cooling and peening Google AR500 welding for a complete description / how to and also Google weld stress relieving.

Side note most guys would have a hard time passing a simple structural weld test with a mig due to poor weld prep and lack of cleaning between passes.

question how thick are the 10" plates?

 

[JByrd]

Re: Welding AR plate ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: procovert45</div><div class="ubbcode-body">esab dual shield II 110 wire for your mig, preheat steel to 400 deg F ,use laser to temp it "harbor freight" as mentioned before KEEP MOVING! dont drag around , if its glowing red you just got it too hot.
OR just take your plate to any good size industrial fab shop with high def plasma table and let em cut you some real purdy cnc holes to run some big fat chains through. prob solved </div></div>

 

[JByrd]

Re: Welding AR plate ?

top part may help ya

 

[DIBBS]

Re: Welding AR plate ?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: caustic</div><div class="ubbcode-body"> question how thick are the 10" plates? </div></div>

<span style="color: #000099">Plates are 3/8" thick
</span>

 

[Rock-N-Ruin]

Re: Welding AR plate ?

7018 stick or E70t-11 fluxcore or MIG E70s-6 wire will do. A quick google search brought up about 4 different "welding AR500 steel" threads on snipershide along with alot of info from the fab webpages...

 

[onetoe]

Re: Welding AR plate ?


I printed these from the manufacturers website. I have welded AR 400 & 500 without any problem as long as you preheat it, use a low hydrogen rod and either put it in an oven to cool down or just throw a welding blanket on it so it doesnt cool to fast and you won't have any problem with cracking. On my targets I always bolt the hangers on them just becasuse it's easier, especially when I want to change the plate.

 

[caustic]

Re: Welding AR plate ?

for 3/8 plate you should (I would) put a bevel of 30 deg or so on at least one of the plates so that you get proper and complete penetration in the weld zone then post heat/slow cool and stress relieving.