I'm fairly new to welding, so I don't have a lot of experience with it. Here's my situation: I've been drilling and tapping holes. Three times I've had the need to redrill the holes because they are slightly off. I welded the holes closed and went to redrill and retap them. Once I had no problems whatsoever, but twice I basically couldn't drill them all the way through. I ended up using a sledge and a punch to finish the hole. I then dressed the hole up with the drill and tried to tap them. They were extremely difficult to tap, and I basically ruined two taps. The resulting threads were not completely cut by the tap, but I could force a bolt into the holes. With all my difficulty, it seems like the metal hardened through the process of welding and cooling too quickly. Is this a correct assumption?? Is there any way to avoid this in the future??
Thanks for any help you can give.