Welding Frame Cracks

I have a couple of pesky cracks in my frame. they originate from the front spring perch on the outside and terminate just short of the inside edge running at about a 45 deg angle to the front bumper. I have welded them already but they keep coming back. The crack is right next to the last weld. I have gouged out the old weld and drilled the end of the crack. I am not a expert welder but have training, it seems the weld is harder then the existing frame material or the heat does something to the frame that makes reoccurring cracks happen. I know flexing the frame is key to the Jeeps ability. Should I double the area? I think it will just move the stress to the edge of the plate If I weld in a plate. Has anyone found a good fix or technique to deal with these pesky cracks?

 

The search tool is a good one!
Here's one for starters...
http://www.earlycj5.com/forums/showthread.php?t=74407

 

hey jhuey
your cracks are in the area of the heat affected zone. this is the area between the hot weld and the material that is at the ambient temperature. the cooler material draws the heat away from the heated area too fast creating a wrought steel condition . this is harder but more brittle than your original designed steel. now you have created a situation where you have two different strengths of steel directly adjacent to each other reacting differently to the same stresses . to combat this you need to preheat the area of the weld , maintain the proper interpass temperature and when the welding is completed the area needs to be wraped in a welders blanket to slow the cooling of the steel . this should give you a better shot towards eliminating those pesky cracks . good luck