Re: Welded Diff
I welded mine a few weeks ago on project CheepJeep. Another alternative is to use ENi-CI (nickel rod) or ENiFe-CI (iron-nickel rod). Being the engineering geek I am, I dug up some AWS journals in my work library that discussed welding cast iron. If you can pre-heat, weld slowly, and cool properly, that is obviously best. If you blast it with no pre-heat, use steel rod, and get it too hot, cracks will form due to the heat stresses induced in the adjacent cast iron that change the composition of CI to brittle Martensite. This is further magnified by the inability of the high strength filler rod, (steel) to absorb any residual stresses. Nickel is a softer and more ductile material that absorbs the residual stresses. The concept is similar to filler materials you put in between concrete slabs to allow for expansion. Nickel-iron has higher strength than nickel rod with similar energy absorption characteristics. I chose nickel rod for the following reasons:
Free, and little or NO preheat when welding above 70°F ambient temp!
I could never nail down the mechanical properties, as they are less than steel rod, but maybe only 10-20%. The trade off is that I didn't have to preheat, and I avoided all the hassles of welding CI properly with steel rods using the proper preheat and cooldown procedures.
I have the article if you'd like to see it for yourself. Good luck. Welding is a cheap alternative if you take the time to do it right. If you want to use 7018 or 6011, make sure you preheat and cool the piece properly.
1976 CJ-7, 304, TH400, Q-Trac, 4:10's, 33x12.5 Goodyear MT's, blah, blah , blah...
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