I'm wondering if you can harden a full anvil? I'm welding together an anvil, it'll end up being around 400lbs. The face will be 4" wide, 16" long, 10"+/- tall, full length will be around 24". Right now I believe the pieces are definitely a mild steel. Can dent them with a hammer, for sure on the sides not so much on the faces. So when I get completely finished, can I just put it in a fire pit, pull it out and quench it in oil? Or should I just weld it up, then weld some 4140 on top? Or any other ideas?