Thread: O1 heat treating problem

Originally Posted by gregg71

I will do this and I will see.

In addition I will make a simple razor fort test.

My plan for the HT:

I leave at least 1 mm (3/8") thikness of the edge.
soaking: 805C / 1480F, 8-10 min.
quenching oil: 50-60C / 130F, 30-60 sec
tempering: after cooling to room temperature, 205C / 400F, 2x1h (between cooling to room temperature) or 1x2h

What do you think? This should work, isn't it?

NO. 1mm is smaller than 1/16", 3/8" is equal to 6/16" which is way too thick for final grind. .

I would leave my rough grind about 1.5 to 2 mm, which is between 1/16 & 1/8". Our measuring system here in the U.S. is not near as good or simple as the Metric system. With this being a worldwide forum & Americans being the oddball out when it comes to measuring, most of us here on this forum can work in mm & cm pretty easily. Heck, I've even gotten better and I am a bit slow.

I believe any of those HT recipe's would work if your rough grind blade edge would be thick enough to hold the heat until the steel hits the quench.

Yes, sorry. 1/16" = 1,59 mm. For me much more simple to use the Metric system.

Than I will grind it about 1.5 - 2 mm. I jus read that somebody is leaving the total thickness before the HT: ~6 mm. Thanks!

While we can discuss this till the cows come home, if the blade doesn't shave, I would remove the scales. They are nice. Then clamp the blade in a vise with the shoulders so that the blade section sticks out, and hit it with a hammer to break it.

What will happen will give you a lot of information that you really need in order to understand what went wrong, and what you can do to change it. Most people here who make blades will break them sometimes to learn from. While it is a shame to break a blade that is 'finished', it will also teach you things you cannot learn otherwise.

I am suspecting the whole heat treat process you used. I am curious why you did not normalize the blade. Normalizing helps the grain structure, so if you do not have a good foundation to start with everything else is doomed from the start.

I agree with Bruno, snap that blade and look at the grain structure. I would then take a piece of it and try heat treating it again after normalizing, then retest.

Is there any need to normalise if you're not forging?

Thanks!

Originally Posted by shooter74743

....
Our measuring system here in the U.S. is not near as good or simple as the Metric system.
.....

For those switching measurement systems there is only one conversion to commit to memory.
And it is exact.

1 inch == 2.54 cm or 25.4 mm
== is short for exactly. It was close for a long time but about 1957 the measurement folk
made the relationship exact.

Thus 1/8" is (2.54/8)cm or (25.4/8) mm

Today I type "convert (1/8)inch to mm" into Google.

Originally Posted by JDM61

Are you using some kid of anti-scale compound and if not, do you have access to some?

An anti scale compound can be a thin glaze of pottery mud (slip) mixed with carbon (powdered charcoal).
Commercial products exist.
The goal is a thin layer that keeps oxygen in the furnace from burning off the carbon in the steel but not so thick
to be a concern at quench time. This has a lot of value on the initial high temp heating including
slowish heating to relieve strain.

As for hardness try small strips of the same steel with little investment in shaping.
Heat, harden, quench and temper each differently so you can compare how they feel
on a hone or under a file.

Preheating and strain relief is worth paying attention to.
The initial heat and quench should max out the hardness of the steel (and brittleness). Tempering is to
calm the brittleness and chipping. Modern hones can sharpen harder steel so a thick spine and sturdy
edged razor can be a lot harder than can be sharpened on an old school Arkansas stone. Your design
and grind will bound the ideal hardness.

Tempering at a lower temp for a longer time gives more control.
Speedy Metals Information for O1 Tool Steel
For tempering wrapping in foil to protect from further oxidation is sometimes
done. Aluminum foil will oxidize "get" some of the oxygen from makes
some sense for tempering depending on the furnace.

One distraction....
Lead+tin and molten salts for tempering have their place with enough ventilation.
Heat Treatment of Steel
The molten lead+tin is used by Thiers-Issard for some blades with special controls and government
dispensations for historic and quality reasons. I suspect it allows them to make a razor with a harder
final R hardness.

Power tools for polishing can be gosh hot and hard on the temper.

Originally Posted by niftyshaving

An anti scale compound can be a thin glaze of pottery mud (slip) mixed with carbon (powdered charcoal).
Commercial products exist.
The goal is a thin layer that keeps oxygen in the furnace from burning off the carbon in the steel but not so thick
to be a concern at quench time. This has a lot of value on the initial high temp heating including
slowish heating to relieve strain.

Sorry I misunderstood this. I do not use such a compound. It sounds good. How much influence the standard HT process? What brand would you recommend?

Originally Posted by niftyshaving

Preheating and strain relief is worth paying attention to.
The initial heat and quench should max out the hardness of the steel (and brittleness). Tempering is to
calm the brittleness and chipping. Modern hones can sharpen harder steel so a thick spine and sturdy
edged razor can be a lot harder than can be sharpened on an old school Arkansas stone. Your design
and grind will bound the ideal hardness.

What do you mean preheatin? The furnace, end/or quenching oil?

Thank you for your useful advices!

Here is a useful chart for you. If it is not clear enough for you, pm me your email and i will send it to you via email.

Thank you so much, it is very useful for me. But just now it was broken the thermocouple in the furnace. Yesterday ordered a new one.

An other useful pic from the Wikipedia: