Welding mild steel to AR-500

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Ref: www.actiontarget.com/pdf/Sales_Sheet_PT_Torso.pdfI am needing to MIG weld a 3/8" thick mild steel bracket to the back of a 3/8" AR-500 target plate similar to the one shown in the above link. I need to minimize the HAZ so as to keep that area from losing hardness. Bracket will be a 2" wide and 3" tall rectangle for a total weld length of 10". I have a Lincoln Idealarc SP-250. What weld technique should I use? What gas? What wire type and size?Thanks in advance.Ace
Reply:One issue with the weld will be the formation of a hard and brittle heat affected zone (HAZ) on the AR-500 side of the weld.  Done properly, this would probably be welded in the annealed condition with preheat and postheat, and then postweld heat treated to hardened the plate as desired.In your case, I would consider welding with 309 SS stick rod.  This weld may be ductile enough to accommodate the weld stresses, and later, gunfire stresses, without failing in the AR-500 weld HAZ.
Reply:is AR plate just quenched mild steel?? We use it at times at work and I just want to know if I am thinking right
Reply:Originally Posted by johnsonmoparis AR plate just quenched mild steel?? We use it at times at work and I just want to know if I am thinking right
Reply:we weld AR 400 and 500 plate to mild steel all the time. our concrete plants and asphalt plants and the rock crushers require a good amount of AR. i prefer to weld with 1/8 7018 with pre and post heat. most of the time my post heat is just warming the entire weld to around 400 and letting air cool. seems to work for us."Retreat hell, were just fighting in the other direction"Miller Trailblazer 302, Extreme 12 VS, Dimension 400, Spectrum 375, HF 251D-1, Milermatic 251 w/ spoolgun  Hypertherm 1000Lincoln sp 1702000 F-450 to haul it
Reply:I wasn't going to answer due to the fact I've only AR400 and not AR500. I used 7018 with no problem.
Reply:backuproller nailed it,  I have always used 7018 with preheat and post heat when welding AR.  Never had a problem.  I have tried with migs a few times, but never got a weld that lasted...I'm a Lover, Fighter, Wild horse Rider, and a pretty good welding man......