Re: welding mild steel to some very hard steel

If you don't know what the steel is you had better be careful. Odds are good that the block is either high carbon or high alloy.
Any attempts to weld will leave you with a HAZ boundry layer that will be extremely brittle. A hanging load, a few weeks or months of vibrations, and down it comes.
I do a demo for students where I have them weld 2 tool steel bars together with a solid 3/8" bead. Let it cool, drop it on the floor and it shatters. Extremely harsh reminder about keeping track of the HAZ.
You could attempt to 'butter' the joint area with some high nickle or maganese rod but you are still on shaky ground. 200 amps on Sched 80 is about as high as you dare to go using a 5/32 rod. If you are using 1/8" rod, it is WAY too high.
Cheers.
Jimmy wrote:

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Thanks guys. I finally got everyone to agree today that this was the wrong way to go. W chunked the hardened steel bar for a piece of mild steel. Got rid of the schedule 80 pipe and replaced it with a mild steel rod the same size as the pipe. Drilled and tapped the bar. Threaded the rod to match and the only weld it got was a tack weld to keep it from coming undone.

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