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the patent behind multi-quench grain growth refinement

Posted by oldsailorsknives 
the patent behind multi-quench grain growth refinement
April 02, 2018 04:23PM
numerous claims are made about multi-quench grain growth refinement. most will base their claims on what is said on pg 69 of Verhoven's Metallurgy for Bladesmiths. It looks wonderful, grain going from ASTM 9 to ASTM 14 in 3 cycles. the reference for this is the work of R. A. Grange in 1965. here is the granted patent [patents.google.com]
what most of us miss when reading Verhoven or Grange is this:
In practicing our invention, it is necessary that the heating be done quite rapidly but once the desired rate is obtained on further advantage results from exceeding such rate by extremely fast heating. In thicknesses up to 0.5 inch, satisfactory results can be obtained by leadbath heating but other types of liquid baths, such as salts, or electrical induction or resistance heating may be used. The heating time should be less than 60 seconds and preferably less than 20 seconds. In such thicknesses as .03 to .50 inch, the same ultrafine grain size was obtained upon heating in a lead bath from 10 to 20 seconds.
does not sound like something I could do in my small knife making shop.
Scott

scott
[www.etsy.com]
me2
Re: the patent behind multi-quench grain growth refinement
April 03, 2018 01:48PM
The salt bath used for Verhoevens work is significant, and I feel the use of a torch is significant for thisvswho use it, like Fowler etc. Rapid heating is critical, but that aspect is rarely given the credit it deserves.
Re: the patent behind multi-quench grain growth refinement
April 04, 2018 06:43AM
the very rapid heating and fast quench seem to be the key for this to work. the maximum temperature is a very narrow range, seems to be +/- 25F. this would not be an issue with salt or lead bath, but how do you control the temperature with a torch? remember we are talking room temperature to say 1500F in 20 seconds or less followed by immediate quench. if the maximum temperature is exceeded, the grain size gets very big, very quick. what prevents a torch refined knife blade from having spots of refined grain next to spots of very coarse grain?
all the work that Mr. Grange did was on basic low alloy steels, 1045, 1086, and 5150. his seems to be one of the few grain growth refinement studies that is supported with actual microscopic pictures of the steel before and after.

scott
[www.etsy.com]
Re: the patent behind multi-quench grain growth refinement
April 04, 2018 10:04AM
Scott,

Rapid heating and rapid queneching is in my opinion easier in a small shop than in factories.
It is ideal for knives.. I am thinking of a small induction crucible with any molten metal
(that have melting temp lower than aust temp for the piece) Most likely I wont use
lead but something less toxic.. this with bunch of thermocouples and at least 2 termometers
and small oil tank is all needed. Oh lets not forget some dry ice bath after quench in the last cycle.

Excellent paper, thanks for posting.

www.instagram.com/jscuttingtools
Re: the patent behind multi-quench grain growth refinement
April 04, 2018 10:36AM
I could see something like that working. I don't see how a quick heat with a torch, quench, repeat 2 times is going to give you refined grain. I also don't see how these folks can claim reducing grain from 10 microns to 5 microns without any lab equipment or microscopes.
does anyone know of any other peer reviewed papers on grain refinement of knife or bearing steel? I have found some papers that discuss grain refinement by adding aluminum or titanium to the original melt, but these were all low carbon steels.
i am just skeptical of grain refinement claims. most seem to be based on the quote from Verhoven's book, but none use the rapid heating and cooling that Mr. Grange said was so critical to achieving grain size reduction.

scott
[www.etsy.com]
Re: the patent behind multi-quench grain growth refinement
April 04, 2018 01:18PM
Quote
oldsailorsknives
I could see something like that working. I don't see how a quick heat with a torch, quench, repeat 2 times is going to give you refined grain. I also don't see how these folks can claim reducing grain from 10 microns to 5 microns without any lab equipment or microscopes.
does anyone know of any other peer reviewed papers on grain refinement of knife or bearing steel? I have found some papers that discuss grain refinement by adding aluminum or titanium to the original melt, but these were all low carbon steels.
i am just skeptical of grain refinement claims. most seem to be based on the quote from Verhoven's book, but none use the rapid heating and cooling that Mr. Grange said was so critical to achieving grain size reduction.

I think to quickly temper only the spine of the knife w torch is possible without harm
but needs lot of skill and thermocouples at the knifes edge and few on the spine
then to be careful not to exceed certain limits..

Al and Ti as a "grain refiners" actually prevent grains from growing as fast or growing more than the certain limit
whenever steel is exposed to high temps.. So ingots or hot worked products (semi-products) can have finer
grains compared to pure Fe-C chemistry but they do not "refine" in the exact meaning of the word.
To prevent growth is more correct.
Same way are used other carbide formers as V most commonly in low amounts.. (can be Nb or Mo etc..)

Scott, You are right, but there will be always many ppl reacting to the first impression of being cool when
they see grinding like thick "stream" of sparks flies to the flooring, torches, flames, lots of cutting w angle grinders
for even more awesome sparks. It looks cool its a steel fireworks smiling smiley

But eventually they must make an inferior product and if their customer base wont notice
it means they did not need a quality tool anyway..

www.instagram.com/jscuttingtools
Re: the patent behind multi-quench grain growth refinement
April 04, 2018 02:26PM
you circle back to my argument. if you want fine grain, go by composition and source. 1084 and 52100 are basic industrial steels that are allowed wide variations in content. W1, W2, O1, M42 will have less variations. certain tool steel alloys, because of their composition, will have very fine grain right out of the wrapper. W2, O1, 1.2519, F1, F2, and others have small amounts of vanadium and/or tungsten that form very small carbides that are well dispersed ,will not break down under "normal hardening", and help prevent grain growth. these tool steels are also 'double killed' by the addition of silicon and aluminum during the melt, which also helps promote fine grain. this is all backed up by peer reviewed books and papers dating back over 50 years. to folks that say they have a magic recipe for grain refinement, I say show me your metallography and micrographs, then i may believe.

on this subject just call me 'Doubting Thomas"

scott
[www.etsy.com]
Re: the patent behind multi-quench grain growth refinement
April 04, 2018 03:25PM
Quote
oldsailorsknives
you circle back to my argument. if you want fine grain, go by composition and source. 1084 and 52100 are basic industrial steels that are allowed wide variations in content. W1, W2, O1, M42 will have less variations. certain tool steel alloys, because of their composition, will have very fine grain right out of the wrapper. W2, O1, 1.2519, F1, F2, and others have small amounts of vanadium and/or tungsten that form very small carbides that are well dispersed ,will not break down under "normal hardening", and help prevent grain growth. these tool steels are also 'double killed' by the addition of silicon and aluminum during the melt, which also helps promote fine grain. this is all backed up by peer reviewed books and papers dating back over 50 years. to folks that say they have a magic recipe for grain refinement, I say show me your metallography and micrographs, then i may believe.

on this subject just call me 'Doubting Thomas"

See how niolox was supposed to have fine microstructure and good toughness,
But when I worked with it, there were signs I was writing on the forum in past..
It needed relatively high aust. temp. to get over 60HRC, corrosion resistance was lower than AEB-L
with tendency to pits as well (sign of non-uniform distribution of Cr and lot of Cr tied in carbides)
And it is harder to polish than elmax !.. Then Larrin published a micrograph on his blog
and so dream of a unicorn is probably over.. Will see if he will confirm it with a second run
of 3 samples from different steel stock.. Luckily I bought only enough for 5 blades..

So absolutely agree ! Why to get a steel thats not ideal and then do lot of
(pseudo) special treatments to get it right with huge space for mistakes..

www.instagram.com/jscuttingtools
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