You can see the exceptions in the other replies, but the only material that
I've used which fairly consistently had a number of very hard spots in it,
was OBF old bed frame angle.
The OBF stuff doesn't MIG weld well, either, IME. I've had deeply penetrated
welds pull out completely, to the root.
Some stainless seel alloys work harden during cutting, and can dull a HSS
cutting tool edge instantly if feed force is paused, but other common steels
I always use a reliable cutting lubricant, not oil or some other improvised
fluid, and generally keep feeding pressure steady 'till the cutting is
Any new hot rolled that I've bought in recent years, still has the scale on
it. I'll grind the scale away for weld areas, otherwise I just clean it
well, and paint.
Diluted muriatic/hydrochloric acid (available in many retail stores for
etching concrete, etc) is effective at removing the scale when the parts can
be submerged in the acid solution.
After treating with the diluted acid, I generally rinse with baking soda
water, then fresh water rinse, quickly/force dry and apply oil (new 30W).
The same acid treatment generally works well for rusty steel and cast iron
parts, although with light rust, I often treat similarly with a diluted
phosphoric acid/metal etch solution, then dry as mentioned previously.
"Pilgrim" < firstname.lastname@example.org> wrote in message
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