I'am modifying a 32 steering box for my av8 project. I'am well aware that the f1 box is a better choice but I would like to stay early mid 40's. I cut,squared and chaffered up the box extension tack welding using a tig welder across from each other so there was a 1/2 inch space between each tack weld. I then heated the unit and welded it looked like it was going good when it cooled I noticed it cracked it the center of the weld. I consider myself a good mig welder with 20+ years experience but the tig is still kind of new to me I'am improving though. The welder is a miller diversion 165 I'am using .045 alloy rod. Can anyone tell me what I'am doing wrong? I have inclosed some pictures.