How to Weld Grader Blade and Bucket Teeth?

I need to make a tool for my excavator that will involve welding a cutting edge off of a motor grader to some old bucket teeth.

I've cracked a few pieces of blade, and I'd like to get some advice on what rod to use, how to preheat the blade properly, peining after welding, and anything else that might be useful.

Any other observations or advice on welding steel used for cutting edges on earthmoving equipment is much appreciated.

Thanks,
DRC

I'll try to clarify this some, I guess I should have given more details the first time.

This is about 3' of grader blade that I need to weld to two teeth that are about 14" or so apart on a 24" bucket. The fit is poor, there isn't a lot I can do about that other than fill it in or weld up some pads on the teeth that conform to the blade.

Last go-around the welds held up fine, but the blade cracked in a few places. Seemed like maybe too much restraint (the teeth were on the bucket, of course), or maybe the temp on the blade came down too fast.

I've tried a few different rods, including 7018, and some rod formulated specifically for wear edges.

I've been welding off and on since 1972, can run MIG, TIG, stick, and gas, (I know those terms date me (grin)),and have welded motor and transmission cases successfully, so I have at least a rough idea of what I'm doing.

This one has me a little stumped, though. I've never seen steel this strong crack like that. If the welds were cracking, I'd figure it was just me, but the welds seem to be fine.

After reading all of your advice I'm wondering about preheating everything to about 350F, welding it up, and bringing it down slowly.

I'm also wondering if I do this, how well can I expect these teeth to fit back onto the tooth mounts when everything is cold.

Again, any advice is most welcome.

DRC

With only two contact points on the grader blade using the teeth as the moldboard backing [2"aprox.] with 10" of overhang and the hyd. rip-out force of the excavator, I think I would take a step or two back and re-think the design on this tool as the grader blade will not hold up to this kind of flexing.

Describe the cracks in the base metal. How far away are the cracks from the weld zone? Grind a V into the crack and see how deep the crack goes. More than one crack? Crack Length and width? Is the crack transverse (horzontial) to the weld joint?

I was thinking you were talking about the welds cracking.

T_Bone

Usually grader blades weld easy without a cracking problem. Did you preclean the area well? Good joint design? Tight fit-up?

I would probably use a torch after grinding clean to remove the steel of any moisture, oil, grease, rust, paint, before welding, about 500�.

T_Bone

Yep I do and thats why I wanted him to describe the cracks. I kinda have a feeling the blade steel isn't a common type.

With the different metal mixing techology into todays world it's getting tuff to recomend a general welding procedure for anything.

T_Bone