Whilst I am perfectly happy to accept Sam’s practical success … I think this needs saying:

There is a big clue in the name of the material : The ‘O’ stands for Oil

Sadly, I note that even this page appears to use ‘0’ in several places **LINK**

AISI 01 Ground Flat Stock

MichaelG.

Heat treat was one of my jobs years ago, use clean oil or clean water & I would imagine your temperature control is not going to be spot on? Most small parts can be water quenched but we generally used oil with little problem.

Tony

In the 70s when I cut my teeth, it was widely held that both silver steel and gauge plate were to BS1407 – same stuff, different profiles – and were hardened and tempered the same way.

Looking on the net now, it seems there are so many different specs offered that it could be anybody's guess unless you've got some sort of release note or CofC to tell you what you've got.

When parts get large, quenching becomes a more sophisticated process to avoid cracking from differential contraction – even in oil. Don't ask how I know…

But for less substantial parts I'd think processing should be simple and not require precise temperature control, to deserve the name of gauge plate.

This little book tells you all you ever needed to know about heat treatment

Tubal Cain

this is the real English TC, not the American pretender.

I use DIN 1.2510 but as far as I can see it is the same type of steel. Oil hardening goes without problems but small items loose heat very quickly and optimum hardness is then not reached. I hold small parts in tweezers/pliers close to the oil container and quench quickly without hesitation. Niko.

I have hardened Oil hardening steel (gauge plate) by quenching in vegetable oil or in water, tempering right after quenching . Complex shapes were quenched in oil and I got it hard enough for the intended purpose, simple shaped tools were quenched in water.

Thor

Whether quenching in oil or water the part must be swirled around in the quench for optimum heat transfer. In water if the part is left stationary it will become covered in bubbles of steam which inhibit heat transfer.

When heating steel without the benefit of a controlled atmosphere there will be some surface decarburization resulting in reduced hardness at the surface. The longer the steel is held t temperature (soak) the deeper the decarb.

Just an idle thought that occurred to me… would there be any advantage in cooling the water / brine / oil in the fridge or freezer before quenching?

No,

Like several others previously I spent a lot of years heat treating B01 (GFS and Silver Steel) and differing tool steels on a near daily and certainly weekly basis. I don't recall taking B01 over 58 – 60 HRc all tested on a (Mitsubishi if I recall correctly) hardness tester

We always quenched in oil (whale oil). The only time we had anything crack in oil was after a particularly cold period where the oil bath chilled overnight. From that point on, a scrap block of steel was heated at the same time as the first batch of the day and used to take the chill off the oil before the first quench.

We were tasked to make a large batch of small cams from silver steel that had a 5mm hex broached in. The material came from Uddeholm a reknowned tool steel supplier. All our heat treatment was done to manufacturers specifications but virtually all of the first batch of components – quenched in water as so defined – cracked in use at the hex. A second and all further batches were quenched in oil with no further issues. Since then I have never quenched silver steel in water at home.

Personally, despite being an advocate of Sparey book I wouldn't use soluble oil/water mix myself but, like so many things, unless you try you don't find out. Trying to get B01 harder than 60 – 62 HRC at home by overheating and or very cold quenching will, in all probablilty, lead to crystalisation that tempering may not improve.

Regards – Tug

They used some stuff called Ucon for quenching where I worked many years ago. It is water based with some organic compound dissolved in it. When it gets hot (close to the job you've jusr dunked) the organic comes out of solution and coats the job, so you get a sort of oil quench but no fire risk. Probably stunningly expensive and only available in 50 gallon drums

Hi Sam,

Perhaps I should have added but like so many other matters in life 'size' needs taking into consideration.

A well damp cloth or asbestos kitchen blanket laid over the quench bath will quickly douse any flash fire but as said depends on the tank size. At home mine is quite small – 6in or so diameter but more than enough for what I do. At work it was about 18" diameter and slightly deeper. With the amount we did at work (mainly batches of small components but occasionally a larger lump) it would often flash over but was quickly doused as above – I honestly can't recall that happening at home even before I had whale oil – then it was old car oil which will readily flash if got hot enough.

Personally I prefer to use oil for the result – not to eliminate the fire risk but each to his own eh

Tug

Personally, despite being an advocate of Sparey book I wouldn't use soluble oil/water mix myself but, like so many things, unless you try you don't find out. Trying to get B01 harder than 60 – 62 HRC at home by overheating and or very cold quenching will, in all probability, lead to crystalisation that tempering may not improve.

Actually Robin I did but as said, though I personally would not try it doesn't mean you shouldn't.

The thinner the section the easier it is to distort on quenching. Any thin part needs to go into the quench absolutely vertical and plunged firmly but quickly. Just dropping the part in will cause distortion as one side cools before the other. The other thing to bear in mind with thin sections is the ease in overheating them in the first instance and the part's inability to heat unevenly if using a flame.

Can I ask what it is you are making and what it's intended use is? BO1 is intended as an oil hardening steel (see Uddeholm spec for it here  but can be treated in other ways. You haven't mentioned tempering – making parts to high hardness (and if done by flame always a potential) – tempering will not improve any crystalization caused by overheating. I should add though, one has to really overheat it to get to that state.

Much has been written in modelling circles on the technical side of heat treatment over the years – all of it valid but I offer my thoughts based on not only on practical experience at work but successful heat treatment at home particularly on making cutting tools.

As an aside I made some small LH thread retaining screws from silver steel for a series of IC engines. These were carefully heat treated (quenched in oil) and tempered. It would be a while later that I had cause to strip one of these engines. The screw removed easily enough but when handling to replace simply broke in my fingers at the thread shoulder, the material completely crystalized and crumbling. Obviously the other engines were checked and all other screws were okay but they are all suspect and require replacing.

Tug

Edited By Ramon Wilson on 04/10/2021 08:29:19