Hardening HR steel

[barksalot]

I have some .250" round stock and some .246" ID x 3/8" OD seamless tubing which needs some drilling out to fit the round stock.

Can HR be heated to a dull red then quenching in oil or water to get any hardening effect.

Mike

[Bessler007]

If steel is heated to a bright red, it will have no attraction for a magnet or magnetic needle, but at about a "cherry-red," it regains its magnetic property. This phenomenon is sometimes taken advantage of for determining the correct hardening temperature, and the use of a magnet is to be recommended if a pyrometer is not available. The only point requiring judgment is the length of time the steel should remain in the furnace after it has become non-magnetic, as the time varies with the size of the piece. When applying the magnetic needle test, be sure that the needle is not being attracted by the tongs.

Black Red
537 Celsius
1000 Fahrenheit

Blood Red
649
1200

Low Cherry Red
746
1375

Medium Cherry Red
774
1425

Full Cherry Red
815
1500

Bright Red
843
1550

...I don't think so. It might need to be hotter.

[rlortie]

Mike,

tempering or hardening metal can be very confusing. surface hardening, annealing, carbon hardening, case hardening, all follow different procedures.

I presume that you wish to harden the exterior for better wear properties.

May I suggest you spend some time on the links found by doing a Google search on "metal tempering". I attempted to post the address here but it is to long.

By the way! this is not going to help you for 1/4" stock, but for short term trial and error research, I use 1/2" CPVC plastic potable water pipe.

Ralph

[barksalot]

Ralph

Yes I was thinking of wear resistance.
I am feeling good about my next mech build and was allowing myself to think about component durability.

I dont think I will take that optional step. Was only curious.

Below is a center punch I made in high school machine shop.
It was heat treated as I described only it may have been heated to a much higher level than dull red. It was 35 years ago so I dont remember.

I still use it in my shop all the time and has held up very well.

[Bessler007]

barksalot,

When you made that punch you might have heated it until there was a slight color that went from one end to the other.

AB Hammer should be able to explain how to temper parts.

[murilo]

Legends say that tempering have been discovered when a researcher guy killed to a slave with a heatted sword...
They got the conclusion that the soul of that slave obviously came into that sword!
And tempering went this way, up to the moment they discovered to a very economic stuff!
They got that the soul of a single slave could make hard to many swords and knifes... The slaves association thanked a lot to searchers...
Later on, the experimenters got that the soul of a pig could make the same effect of the human soul... There came controverses from religious people, since the human soul may not be compared to that of a pig!
( few conservative religious and devocional people kept with the humans... ''human souls are the correct souls''... you know...)
At many slaves and pigs later, the pig association thanked very much when they got that leather in water was also very fine and much better than just water.
Much later, ''they'' got that nitrogen was the secret.
Today, deppending upon aplication, the white steel goes directly to liquid nitrogen!!!
Very interesting to see about japaneese sword makers...
In case of doubt, to get a hard second hand steel for a tool, try to find to a good spring.
regs. M. SP 28/oct

[rlortie]

murilo,

Many may scoff at your above post, but it does make one point, Animal bone crushed to a fine powder has been used for carbonizing or case hardening steel for century's

The carbon center post out of a dead dry cell battery will also provide the same results.

Ralph

[murilo]

Ralf,
even the bones are plenty of Nitrogen.
People also used to several herbs... in water, wich anyway will cause hardening.
I put some story and irony in the history, but it's true.
regs. M.