[TheForge] No need to temper this blade

[Doug Ayen]

Quoth Barking Crow (mail at barkingcrow.com):
> Yesterday at our FABA meeting in Sneads Fl. John Butler demonstrated the
> steeling of wrought and mild steel tools.  It was a great demo and he made
> it look easy as all the welds took first time.  On the chisel blank that
> John forged he welded a piece of old file to a piece of mild steel and in
> the later discussion said that he would quench it in oil and that there was
> no need to temper this chisel blade as the tool steel  was forge welded to
> the mild steel backer everywhere and therefore he didn't have to worry about
> tempering the tool steel to keep it from being too brittle and breaking as
> the mild steel would be dead soft and tough.  This was an interesting  new
> concept for me.   It would end up sort of like the expensive Japanese
> chisels.  So, I'm wondering what experience or thoughts you guys have on
> this decidedly apolitical subject.  Do you think there's an advantage to
> having a mild or wrought backer to a steel blade?  Why?
> 
> Thanks,    Jeff Valentine
> 
> 

It's a good technique, but I'd still temper back a bit if the edge was
going to be under any significant strain. Remember, the edge isn't
going to have any supporting steel under it, so the benefits of having
a maleable backing material only extend as far as the softer material
does.

I've done some historical reproductions of axes and knives which used 
wrought iron for the body and had a welded-on steel edge. Historically,
it wasn't done so much to let you have an extremely hard edge as to save
on expensive and hard to make steel.

For a paring chisel or razor, with a good heat treat that didn't overheat
the steel and a softer quench like oil, there's no real need to temper
back much if at all. For a knife, motising chisel, axe, or other tool
where the edge is going to experience a good deal of strain, though,
not tempering is begging for the edge to crack, chip, and break off. 

--doug