Anvil Quenching Video

[JHCC]

A cool little snippet showing a pair of B&W Anvils being hardened in the factory. Interesting to see how the quenchant is blasted down the length of the tank, rather like one of those endless swimming pools.

https://fb.watch/lNvg2c2zS7/?mibextid=DcJ9fc

(Apologies for this being a Facebook video; I tried to find some other format, but without success. If anyone runs across a YouTube version or the like, please post a link in a comment.)

[Frosty]

That is a cool video, thanks John.

Frosty The Lucky.

[arkie]

Interesting video.  Thanks for posting.

The high volume of water flowing through the pit is probably similar to the flow of water that Mousehole Forge used in the partial diversion of water from the River Rivelin and the mill pond when quenching their anvils.  The flow at Mousehole probably was somewhat less.  (Source: Richard Postman's book, Mousehole Forge).

[JHCC]

Exactly; the rapidly moving water breaks the vapor jacket and cools the metal faster. The only difference — apart from Mouse Hole Forge using water and B&W using what I assume is some engineered quenchant — is that the former used gravity and the latter is using mechanical means. 

[TechnicusJoe]

This is not how anvils used to be heat treated or should be heat treated. 
This is similar to hardening a hammer all the way through or fully on the surface, which really is not a good idea. 
The flowing water is key, that is desirable, and with large sizes even a must. I would approach the quench differently. 
But I suppose this works well as well. That, they understand at least. 

I have had comments from people on my anvil videos saying they would heat treat the anvil upside down and leave it in the water (no water flow) so it could cool down. 
These individuals really don't know and/or understand the circumstances and how heat treatment works, let alone on an anvil. 
You will get a steam jacket around the anvil and it will never cool down fast enough to heat treat the face, that it actually becomes hard. 



In the case of anvils, hammers and alike, it is the working surface that needs to be heat treated to provide a lasting work surface. 
The body needs to be tough to support the heat treated the face and absorb the impacts and vibrations, so that anvil doesn't want to break. 

Nobody here will have to think about why a glass hammer, anvil etc. is not a good idea. 
The same applies to heat treating an anvil all the way through or simply the entire outside surface, depending on what alloy is used here. 

You can tell me about tempering the body, or trying to temper the body, but it is not a good way, nor is it efficient. 
The face (and horns) needs to be heat treated and the body underneath needs to stay cold enough to not heat treat, leaving the body tough. 
Thus you have to heat less material for a shorter period of time with less energy or fuel. 
If required, tempering can be done much easier and faster, without the risks of the body getting cracks during the heat treatment. 

Now the video is cool and it is nice to see something like this. 
But, in this day and age with so much info. available and anvil production having been an incredibly well established process, it boggles my mind to see such an undesireble heat treatment as this. 
There is so much more to anvils than being a block of iron. 
Not that anyone here says that just now, but it boils down to that most of the times. 

I best stop now, before I continue my rant into a books worth amount. 

[JHCC]

My understanding was that this is how all-steel anvils are hardened these days (including those from Holland Anvil, Ridgid/Peddinghaus, Fontanini, etc), followed by heating in a tempering oven to the appropriate temperature. That is basically the same as most industrial heat-treatment these days, and I don’t know whether industrial heat treaters even offer differential hardening  

I’ve sent a message to IFI member foundryguy (aka the guy from Holland Anvil) to ask him to chip in. 

[gewoon ik]

Yes they do offer differential hardening.

Otherwise large gears would not last long. Again ship size large.

And they harden the surface even more against the friction.

But i can't go deeper in explaining because that is about everything i remeber about the shoptour i did.

 

 

 

Edited July 22, 2023 by Mod30
Remove excessive quote.

[Goods]

This discussion could get interesting. I would not be surprised that full hardening and furnace tempering is the preferred method these days due to the knowledge required of the workers involved in the process. The easier it is to follow a simple recipe, the more likely you can find and afford the labor. This is a complete guess on my part.

The other side of this is that the materials knowledge has grown significantly over the years. I imagine they are getting exactly the performance they require out of the product, be it gears, shafts, stamping dies or anvils.

Differential hardening is very common, specially surface hardening. I have lot of parts in my shop that have been surface hardened: linear shafts, stamping die guide posts, large gears (15” dia) and even a couple small gears (3” dia). All of these salvaged for reuse… I have not seen any parts that were fully heated, quenched, and the selectively (?) tempered like what we would do with a heated drift when tempering a hammer head. (I’m not saying it not done in industry, just that I haven’t seen it.)

Keep it fun,

David

[Frosty]

The video didn't show how long they left the anvils in the quench or what they set them on when removing. They could've timed the quench then placed them on a quench plate type heat sink to allow the residual heat in the body to temper the face. 

It's one of the frustrating things about these brief videos, they tend to show the exciting parts and leave out the bulk of the processes.

Frosty The Lucky.

[patrick]

Heat treating large pieces is a topic on which I am a bit of an expert (professional metallurgist in an open die forge shop for 20 years) so I thought I'd chime in on this discussion. The quench tank shown in that video is pretty standard for any company that is heat treating large steel parts. In the shop where I work we have two-both containing 50,000 gallons and both capable of handling 50,000# of steel at a time. These are not the largest we have in the company, just in the shop where I spend most of my time. In modern industrial practice, full heat treatment, that is fully austenitizing the entire cross section and quenching it, is common even when some later heat treatment will be done to obtain different properties on the surface. Some folks already mentioned gears, and this is a good example. A surface hardened gear, especially one that is used in a large mining vehicle like a dragline, (these gears are roughly 15 feet in diameter or bigger) are often made from grades like 4340. the gear is quenched and tempered in a bulk manner to achieve a hardness/property combination that gives the necessary core toughness. This might be a rockwell hardness of 30-35 HRc. Later, after the teeth have been machined, the surfaces are re-heated using inducting heating or an oxyfuel torch and quenched. Tempering is done at a low temperature to preserve most of the hardness in the surface. The depth of this surface hardening can be adjusted a bit, but is usually well under one inch. This approach results in a good combination of toughness in the core and wear resistance on the surface. An alternative method to this is to use a steel grade with lower alloy content, for example 8620, then instead of performing a bulk heat treatment as described above, the entire part is austentized in a high carbon atmosphere. The carbon will diffuse into the surface of the steel increasing the hardening potential at the surface. The effect is essential the same as if you forge welded a high carbon piece of steel to a low carbon block. When the entire thing is heated and quenched, only the high carbon portion gets hard.

This brings me to the properties needed for anvils. As Joe noted in his post, an anvil does not need to be hard all the way through. Historically, they were not hard all the way through because the desired properties could be most cost effectively acheived by forge welding a higher carbon plate to a low carbon body. Prior to about 1860, the cost of steel was so high that it was used extremely sparingly. Since only the high carbon plate has the potential to get hard, there is no benefit to heating the rest of the anvil for heat treatment and if you did, you might struggle to cool the plate fast enough to get the desired hardness.

In modern manufacturing, casting is the preferred method (that is most cost effective) of making anvils. Steel is one of the cheapest materials available on the planet, so there is little reason today to make an anvil of composite construction. It would actually be more expensive to do that since labor is so much more costly than material.

Today, there are a wide variety of alloys available. Some are through hardening in large sections, others are not. For a period of time, new anvils were being imported from the Czech republic and being sold by Old World Anvils. These were made from grade 1532 which is a medium carbon steel containing only manganese and carbon as alloying elements. This grade is NOT a through hardening grade in anvil sizes so even with a quench as shown in the video, only the surfaces would be hard. A very effective anvil with a hard face could be made from this grade by induction hardening just the face, but hardening all the surfaces would not detract from the anvils performance. 

The Nimba anvils were made from 8640 and I've head of others being made from 4340 and H13. All three of these have the potential to harden uniformly in typical anvil sized sections. Doing so is not necessarily going to result in an anvil that is more likely to break. Some modern steels can be both hard and tough at the same time, and though toughness does decrease with increasing hardness, as long as the toughness is high enough, there will be no issues with performance.

An anvil with only the face hardened is not necessarily going to be a better performer than one that is fully hardened or surface hardened all the way around. Performing surface hardening on an anvil is a fairly unique process and few heat treat shops are equipped for that type of work, so what you see in the video is actually typical, not an indication of ignorance on the part of the heat treat shop. AND.... When it comes to this type of thing, the responsibility for defining the products properties lies with the purchaser, not the foundary/forge shop/heat treater. If the person who had the anvil made didn't want a through hardened part that should have been specified on the purchase order. Most likely doing so would actually raise the cost of the part since unique heat treatment facilities are required for that.

 

[Frosty]

Thank you Patrick, good to have the straight story. 

I do have a "maybe" question. Fisher anvils have a hard faceplate welded to the cast iron body in the mold. Fishers are renowned for being a quiet anvil. I believe on my not minimal knowledge that the different resonant frequencies between HC steel and cast iron self damp the sound of impacts. 

To corroborate my hypotheses I remounted my Soderfors anvil with the deafening ring from a wood block stand to a steel tripod. I could've used another wood block the first one lasted about 20 years but thought of the different resonances damping and thought I'd give it a try. The Soderfors is very  much quieter only a rap on heal or horn make a loud ring but it's very short lived. Worked a treat for my Trenton too.

So, that's my maybe question. Can differential hardening produce resonance frequencies different enough to self damp?

Or am I completely wrong from word go?

Frosty The Lucky.

[JHCC]

Thank you very much, patrick. As Frosty says, it’s good to get informed input. 

Frosty, I think the quietness of cast iron/steel anvils (Fisher, Vulcan, etc) is more a product of cast iron not being particularly resonant in the first place. While it’s certainly true that putting a loud anvil on a steel stand will quiet it down significantly, we shouldn’t confuse similar effects for an identical cause. 

[patrick]

Cast iron, and specifically grey cast iron which is what Fisher, Star and Vulcan anvils used for the body, has so much carbon in it that much of that carbon exists in the form of graphite. In the case of grey cast iron, this graphite is in the shape of interlocking flakes. It is this shape of graphite that is changing the resonance characteristics of the metal. If you compared this to ductile cast iron in which the graphite is in the shape of little balls, you'd find that the ductile iron rings much like steel. This is also why grey cast iron is so brittle. The graphite flakes act like cracks or even voids. Since there are so many of them, the distance an actual crack has to travel through the metal between the flakes is pretty short. I usually describe grey iron as "pre cracked" metal. It has it's uses, but it is not my favorite material.

Frosty's question was about the difference in resonance based on hardness. There is some measurable difference in this quality, but this not usually the dominate factor in anvil ring. That has more to do with the shape of the anvil and how it is mounted. If the mounting method limits the vibration of the entire tool, then you wont get much ring. There is a method of evaluating hardness based on ultrasound. I don't recall the ASTM spec that gives the method for the test because it is not one that we use, but it is used when you need to evaluate hardness without leaving any marks on the part.

A simple way to test the resonance question is to take a round bar of hardenable steel. Drill a hole in hole through one end so you can hang it on a string. Anneal the bar, string it up and strike it. then quench the bar and repeat the experiment. If you are really curious, temper the quenched bar at increasing tempering temperatures and repeat the ring test. By using rounds of the same steel grade, diameter and length, you remove the geometry/size variable and can isolate only the microstructure variable. A further test that could be intersting would be to compare the resonance properties of anneal, worked hardened and quenched and tempered specimens since, in some cases, you can achieve the same hardness via cold work that you can via a quench and temper, but the microstructures are different. 

 

[gewoon ik]

Thanks for the info. 

[Frosty]

Thanks Patrick. I get the difference between flat and spherical crystal / molecular boundaries and fracture initiation. Grey iron being loaded with graphite and not resonating makes sense. 

Frosty The Lucky.

[patrick]

Frosty- It's not the presence of the graphite but its shape that makes the difference with respect to properties. By making the graphite round balls as in Ductile iron, you get a material that has good toughness, in some cases on par with steels, but it still has the casting advantages of a very high carbon material (lower melting temp that steel and good flow characteristics in molds). Ductile iron was developed in the 1950s and is arrived at by adding Magnesium to the liquid metal just before it is poured in the mold. This is what make the graphite take on the ball shape. Prior to this, a similar structure could be achieved by heating grey iron for several days or more to high temperatures. This process also resulted in spherical graphite an iron processed in this way was called Malleable Iron. It is no longer made as far as I know since ductile iron is so much cheaper and faster to make.

[Frosty]

Yes, that's why I mentioned being familiar with flat vs. spherical crystal boundaries. I'm only passingly familiar with ductile vs malleable iron, just familiar enough to be able to look it up without having to read a whole book. 

I've drilled and tapped a couple holes in the frame of my 100 year old Little Giant and the cuttings were more like dust than steel cuttings. Some was actually platy crystalline graphite. I saw non-metallic glints and took a look through my loupe. I was pretty surprised how much there was, I didn't expect the carbon to be visible.

Frosty The Lucky.

 

 

[foundryguy]

Hey friends, Greg from Holland Anvil here. I was asked to toss in my 2 cents on this topic. 

Heat treating is a complicated topic as seen in the many comments on this tread. We out source our heat treating to a couple different companies. On our H13 anvils. They are fully machined then hardened in a vacuum furnace by quenching them with liquid nitrogen and then tempered twice. This is the only steel we make that is hardened in this process. It is very predictable coming out of temper which gives us great consistency in hardness. The down side is, it is very expensive costing us just under $1.00 per lb. We get very little scale during this process, in fact they look brighter coming back to us than when they are sent. Typical steel hardening leaves a dark scale that is blasted off. Another thing  about this process, we do not see any distortion to the part itself. Most castings would get hardened, then machined. We do not need to do this on anvils. 

We pour 8640, 4140 and other steels that can be normalized or quench and tempered then machined by our customers. They would typically be done in a more traditional method that is not done in a chamber void of oxygen. Prices for a standard Q&T might be in the $.25 to $.45 per lb range

Honestly, heat treat could be a college course as there are so many processes. Luckily west Michigan has quite a few companies that are specialists. Typically, large foundries have in house heat treating although a vacuum furnace with a nitrogen quench might not be part of it.  

Cheers friends! 

[anvil]

Awesome info! Thanks! Brought to you daily only on IFI.

[Latticino]

On 7/24/2023 at 12:17 AM, patrick said:

Ductile iron, you get a material that has good toughness, in some cases on par with steels, but it still has the casting advantages of a very high carbon material (lower melting temp that steel and good flow characteristics in molds).

patrick,

There was another question on the forum regarding ductile iron that I hope you might be able to address:  Will ductile iron anvils work harden over time with regular use like a cast steel anvil does (or one with an added tool steel faceplate)?  

[JHCC]

While we're waiting for patrick's answer, I did a quick websearch on "Does ductile iron work harden?" and got a couple of responses that said that austempered ductile iron does indeed work harden. Now, I have no idea whether or not all ductile iron is austempered, if other non-austempered ductile iron (if there is such a thing) work hardens or not, or how work hardening affects or is affected by other surface hardening processes (induction, flame, laser(!)) performed on ductile iron. So many rabbit holes, so little time....

[Mod34]

MOD NOTE: patrick's reply to Latticino's question has been split into its own thread: