I’ve been making more axes recently and so far have used 1080, 1080+, 5160, 1045, and 1084 as bits. Any thoughts on which is the easiest to forge weld (in a gas forge) to a 1018 ax body or do they all generally weld the same? 

I've used 5160, 1075 and 1084 for bits on axes and hawks.  Haven't made a tremendous number, but don't really notice any major difference between the forge welding.  I would consider taking the 1045 out of the mix unless you are going for a axe/hawk that is primarily for throwing.  With the inevitable carbon migration you might end up with an edge that doesn't have the carbon content to harden as much as you would like.  Not as critical for a throwing axe, IMHO, where toughness can trump hardness, but each to his own.

Thanks for the suggestions. Still working out the ax welding approach that works best for me (and my forge). Maybe this is common but I find that the thin edges of the slit end of the body don’t tend to weld so well. As a result there is a bit of grinding or filing to get back to a solid weld. 

thats why we weld it before thinning

Seems to be very common in both folded and drifted ax bodies to to taper down to a thin edge where the similarly tapered bit gets welded. 

 

I definitely will keep on practicing....

Would O-1 be suitable for a hatchet bit and what thickness steel would be best.  3/16 in. or would thicker be better?

O1 holds a good edge but do you think its good for resisting impact too?

I’ve done a few with 8670 which seems to be a good steel for this purpose. Info from Alpha Knife Supply:

“This steel is used extensively in the lumber industry for making large circular saw blades.

The nickel add toughness and there is enough carbon for good edge holding. There is not enough nickel to make a good shiny layer in damascus.

Think of 8670 as an improved version of 5160, better toughness and edge holding.”

I just did my first welded axe head a few weeks ago with a chunk of leaf spring (unknown, but sparked consistent with 5160 or similar) as the bit and it welded super easy. It was a sandwiched wrap as opposed to drifted with a split insert though. 

I went with the thick weld option (1/4" on each side of a full thickness leaf spring bit) to allow for plenty of compression and post-weld shaping. 

Anyway, it welded so easy it will definitely be my go-to (I have enough of that particular leaf spring for dozens of bits). 

Good that you left a hefty amount of steel to work with after the weld. I got rather thin on my first few. 

Yeah, I made that mistake on my first rail spike hawk that I tried to steel. I kept chasing it and chasing it, even cutting it back to where I finally decided to give it an overlay instead of an insert. That might be a good option for those you've already forged thin.

Better smiths than I can probably weld the bit inside of thin lips all day long, but I try to make things easy for myself.