Metalurgia, forja y fundicion

I have just revamped a Baltic birch core box that I have been using over the last 3 years. It is 18” long and triangular in cross section with letter located near its interior apex.

A seemingly good approach to coating it has been to spray it with a couple coats of shellac and then a few coats of sprayed while lacquer. The lacquer tends to reveal any surface dents or high spots which I then either sand off or fill with spotting putty or slightly thinned Bondo two-part putty.

Then I have...

What is the Slickest Most Adhesion Resistant Prep for Sodium Silicate Core Boxes?

the Petrobondforsale guy seems to be out of business.

anyone have another supplier???

Just curious.
Does anybody measure temperature ? Infrared pyrometer, thermocouple ?

I kick off.

I use a type S (K is too unstable and not high temperature resistant) thermocouple sheathed in alumina but can only measure swirling air/ gas temperature around the crucible. This TC is very durable. I have no means of measuring metal temperature as the couple itself dissolves in the metal (when immersed without sheathing) or the sheathing gets wetted and when pulling it, the wetted sheathing...

Do you measure metal temperature and how ?

I recently built a cheap thermocouple and it works great unfortunately the thermocouple itself is melting are you supposed to use it in the metal or hold it over the metal just a question? The thermocouple I purchased is below... I'm pouring bronze

As part of my ongoing FFA (Future Founders of America) project I have promised a 9-year-old that we will cast an aluminum snake. She has been interested in my foundry for the last year or so. (She is one of the girls I showed in a thread a while back casting an “R” in my foundry). She likes snakes and expressed an interest in casting one in aluminum.

So, I found a rubber snake for not much on Amazon that she likes. It is about 6 x 8 inches in its coiled shape....

How to Part a Snake?

Muy buenas a todos:

Hoy traigo una funda para el cinturón que será regalo para uno de mis mejores amigos.  Como he dicho es para una "curra" que así han bautizado mis amigos a estas navaja de Don Francisco,  " El Curro ". Los 3 tenemos una de estas, ya os presentaré las piezas que tengo de este caballero, que se merece un post para el solo.

Como mi amigo lleva su navaja a trabajar y dice que en el bolsillo le molesta, pues que mejor que una fundita que pueda llevar en el cinturón del trabajo. Voy a las fotos.

Esta vez hasta he hecho un pequeño diseño en papel. Vamos mejorando.

Cortadas las 2 partes, hunedecemos y dejamos que la parte de arriba coja forma para que la navaja ajuste bien bien.

Parece que va a ajustar bien, todavía quedan cosas por hacer.

Lijado, bruñido, perforar para unos remaches. Jodó, un esquinazo! Lijado, lijado, bruñido........ y así hasta que quede como queremos.

Resultado final, siempre mejorable, al final me entró prisa y....

Ajuste, ese punto me lo he ganado, creo. El cuero está vez no me ha quedado rígido en exceso, mantiene la pieza muy ajustada y la sacamos de la funda fácilmente.

Por último una presentación con mi navaja, la de mi amigo es en micarta negra con un borde rojo. Creo que la funda en ese color le quedará mejor que a la mía.

Gracias por pasar por aquí.

Un saludo.

Buenas compañeros.

Como pongo en el titulo mi duda es como hacer el primer vaciado del filo. Hasta ahora los estoy haciendo a mano con la de vaciado de las meigas  o la mayoria de las veces con la piedra de 200 de un kit de afilado tipo KME con angulo controlado.

El tema es que me pego una hora solo para sacar el primer filo y luego otro tanto para afilar y pulir. Ultimamente estoy trabajando con acero 1095 que se pone muy duro y me cuesta la gota gorda sacarle ese primer filo.

Tengo un par de cuchillos para pruebas y les he sacado el microbisel con la lijadora de banda con lija de grano 240 , mojandolo mucho y con pasadas suaves y rapidas. No parece que queden mal pero tengo dudas de si se ha podido destemplar el filo. Estoy haciendo pruebas con ellos y parece que retienen bien el filo. Recuerdo que solo es sacar el primer filo, luego sigo con piedras.

Pues eso.....como lo haceis vosotros??

Por si sirve estoy afilando normalmente a 20º

Imagino que aunque se destemplara el primer hilo de filo al afilar luego a mano esa parte sale fuera.

No se.....tengo en la lista de compras una esmeriladora tipo tormek algunos puestos por detras que otros cachibaches, no se si voy a tener que subirla unos puestos en la lista de la compra.

Otra cosa ya que estamos, a que medida dejais el filo antes de afilarlo. Digo despues de biselar y antes de afilar. Yo lo dejo sobre un mm  o menos . Vosotros??

Saludos.

Hace tiempo descubrí que una de las cosas que más me relaja es coger un "cacho" palo y mi Mora Carving, echar camino alante y sacar viruta para acabar en el chiringuito junto al rio, echando una cañita mientras continúo con mi faena.  Sobre todo cucharas o tenedores....me resulta relativamente fácil y son resultones....

 

.....consciente de mi "ansia viva" por los filos porque no intentar hacerme unos cuchillines de talla jajajaja. Pues ni uno ni dos .....seis salieron.....y ahi van.

Las hojas salieron de unos discos de corte y tras hacer el primero a modo de prueba templando y reviniendo.... funcionó.

Tras el REVENIDO sesión de codo y lija....(pendiente dejo mostraros lo que salió de esa vieja lima de Bellota)

toca elegir la madera para los cabos

 

v

Un buen tarillo de lija y a dar forma....

un poco de magia jjjjjj

para los cabos madera de Roble Americano y Fresno y para las virolas de izquierda a derecha Cocobolo, Granadillo , Palo violeta y Granadillo

Muchaaaaaasss fotossss.....

No van mal y cumplen su función . Ahora tendré el dilema de cual llevar jajajjaja.

UN cordial SALUDO y muchas gracias por llegar hasta aquí

Buenas tardes compañeros. Esta tarde he decidido, por fin, dar el último acabado a una caja que realicé hace tiempo y de paso mostrar su contenido.

Envejecemos suavemente las esquinas.

En este caso solo vamos a encerar.

Terminada, el trabajo de marquetería fué laborioso.

Mostramos el interior, tampoco se queda atrás.

El contenido.

En detalle.

Este verijero lo compré en la caseta de Argentina de la feria de los pueblos de Fuengirola. Evento anual que se celebra los primeros dias de mayo. Acero al carbono, accesorios de plata y la madera creo que es quebracho, espero que un compañero del otro lado del charco, lo confirme o lo desmienta.

Lo cierto es que el cabo venía liso, asi que le realicé un gallonado, le inserté latón y madreperla, una discreta decoración en el lomo y pulido.

Adjunto una foto que he conseguido recuperar de aquel proceso.

El plano inclinado donde reposa el cuchillo en la caja tiene un imán interno de seguridad, no quiero el cuchillo bailando por ahi, y poco más. Buen fin de semana a todos.

PACO.

 

 El granate o granada ha sido una gema considerada durante mucho tiempo como un símbolo de amor que esconde una especie de romance e incluso de pasión. Es costumbre regalar joyas con granates cuando se quieren confesar su amor, aunque a veces sucede que la gente compra ese tipo de joyas para sí mismos con el fin de agregar fuerza y ​​confianza en sí mismos. En todo momento, al granate se le atribuyó hechicería y propiedades curativas. Los curanderos recomendaron llevar un granate para los dolores de cabeza y los procesos inflamatorios de la garganta. Se cree que el granate es una piedra, un talismán para las personas que se han dedicado a la creatividad: artistas, músicos, poetas. Por eso los granates ayudan a los jóvenes a encontrar sus caminos y propósitos, ayuda a reconocer y mostrar sus talentos.

Evidentemente, esta piedra recibió su nombre por el parecido con las semillas de la fruta exótica llamada granada. Sin embargo, los colores del granate pueden ser muy diversos. Los hay un grupo bastante grande de piedras preciosas de varios colores y calidades, por lo que es muy fácil encontrar gran variedad de falsificaciones en las joyerías.

El más común de la familia del granate es el almandino. Viene en todos los tonos de rojo, marrón o carmesí. Esta variedad es valorada por los joyeros por encima de todas las demás. 

El Demantoide es una variedad transparente que parece un diamante. Al sol puede brillar con todos los colores del espectro solar. La variedad más rara de granada es la uvarovita, un mineral de color similar a la esmeralda. Esta piedra era un tipo de granate favorito del gusto de la emperatriz Catalina la Grande.

La joyería con granates es un regalo tradicional y se ajusta muy bien para los enamorados, cabe destacar que es igualmente para hombres y mujeres. El sexo más fuerte seguramente apreciará un regalo en forma de anillo, una pieza original o un rosario, pero las bellas damas siempre están felices con anillos, aros y colgantes.

Esta piedra es ideal para personas sinceras y de mente abierta, así como para personas apasionadas. Según los astrólogos, la granada puede servir como talismán para los nacidos bajo el signo de Acuario, Capricornio, Escorpión, ayuda a estas personas en el amor, en sus carreras profesionales y los negocios.

Hay varias formas confiables de distinguir un mineral natural de un falso.

1.El granate natural tiene la capacidad de magnetizarse. Si lo coloca en una balanza electrónica y acerca un imán a una distancia corta de la piedra, la lectura de la balanza disminuirá. Una falsificación no tiene esta propiedad.

2. La dureza de un granate genuino es dos veces mayor que la del vidrio, por lo que puede rayar el vidrio con una de las mismas piedras.

3. El color y el brillo de un granate natural no siempre son ideales.

4. En la naturaleza, el mineral de granate se encuentra en tamaños pequeños, no más grandes que un grano de café.

 

Escrito por: Alejandro Glade R.

Buenas. Ando buscando la ficha técnica del acero 9260 pero tras varios intentos por la web no doy con ningún sitio donde poder verla.

Busco info de este acero en concreto por varios motivos, va a ser mi primer cuchillo templado y parece ser que el tratamiento térmico no es de los más complicados (por lo que llevo investigado) aparte de que es fácil de conseguir es uno de los candidatos para principiantes (otra cosa es lo que salga).

De leer por aquí y por allí  (hay más paja que grano) creo que tengo más o menos claro el tema de grados para los diferentes procesos pero para ir sobre seguro estoy buscando su ficha técnica y parece ser que no doy con la tecla correcta.

Cualquier ayuda y consejo son bienvenido gracias.

Buenas compañeros.

Estoy haciendo pruebas con diferentes aceros y me gustaria saber cuanto de duros se ponen segun el acero o el tratamiento termico. La tenacidad o flexibilidad con doblarlos hasta partir algo sacas, pero la dureza se me complica. Con meterle la lima para ver si ha templado no me quedo del todo convencido.

Conocia las limas de dureza y el otro dia vi en la web china (ali...exp..) un durometro tipo boligrafo que viene con una peana de acero para calibrar. No se si merece la pena el durometro o con las limas ya sacas suficiente informacion.

Alguien usa algun sistema de estos o cualquier otro??

Se que hay durometros industriales que seria lo suyo pero tampoco quiero gastarme un pastizal en la maquinita.

Los durometros tipo boli valen sobre 100-150 € y las limas algo menos. No se si merecen la pena.

Pues eso....cualquier info sobre este tema me iria muy bien.

Saludos.

Thanks to JimHSoars, Gregory Gallant, Dan, Paul Hutchings, Stephen Ostdiek, and Maxi for becoming Knife Steel Nerds Patreon supporters!

YouTube

The following information is also available as a YouTube video for those that prefer watching to reading. The video might be more fun though there are more details and more discussion in the article.

Oil

One common rating method for quench oils is the quenchometer “nickel ball” test. A 12 mm nickel ball is heated to 1620°F and then quenched into 200 ml of oil. Nickel reaches the Curie point at 670°F at which point it is attracted to a magnet.

The nickel ball is held on a string and a magnet placed outside of the beaker so that when the nickel ball becomes magnetic it is attracted to the side of the beaker. At that point the test is stopped and the time taken. A general ranking of different quenchants is found below:

Parks 50 and AAA are quite commonly known oils among knifemakers. Parks 50 is a 7-9 second oil, clearly in the “fast oil” category. Parks AAA is a medium-fast oil, taking 9-11 seconds with the nickel ball test. I bought my oils from Maxim but since then DuBois has an easy online store available for these oils.

Quenchfast and Quenchall are offered by McMaster-Carr as “11 second” (Quenchfast) and “28 second” (Quenchall) oils. I asked McMaster-Carr for more information on the oils but the sheet they sent me (hosted here) doesn’t have any more specific information on the nickel ball test ranges. In fact, for some reason the datasheet calls Quenchall a 26 second oil instead. The buckets say Reladyne oil but contacting Reladyne led to nothing; the person I spoke to on the phone didn’t seem to have any information on the products whatsoever and kept asking me for an order number. Of course giving them the McMaster-Carr order number just gave an error in the system.

The Citgo Quenchol 521 came from Jantz. Jantz lists the oil as “14-16 seconds” on their sheet, but the datasheet from Citgo lists the oil as 16.1 seconds, which looks oddly specific when the other products have ranges.

So the ratings of the oils are not quite as simple as I might have liked. There are other products available, of course, notably Houghton makes a range of oils at different speeds. If you have a supplier that regularly sells 5 gallon containers of Houghton oils those are worth looking at as well.

Canola, Motor Oil, and the Inconel Probe Test

Knifemakers looking for oils to use that are cheaper than those available commercially most commonly use canola from the grocery store. However, some will also use motor oil. I found a study on 1045 steel where they found canola to quench more rapidly than motor oil so I am going to stick with canola as my “cheap” quenching option to test.

Data adapted from [1]

Despite quite a few studies that looked at canola oil I did not find any nickel ball measurements. This seems to be because the nickel ball test is outdated and has mostly been replaced by the inconel probe test.

The inconel probe test is similar but the probe can measure the temperature of itself during quenching to generate more information about the quenching process rather than just generating a time in seconds. So you get a curve such as below:

The blue line is the normal time vs temperature curve, and the orange line is the “instantaneous cooling rate” at each position. In other words, the slope of the time vs temperature curve at each position. You can see that the cooling rate is relatively slow at high temperature, then accelerates to a peak cooling rate around 1150°F and the slows down to about 600°F where it becomes more stable. Those three stages are the “vapor blanket,” “nucleate boiling,” and “convection” phases, which are also shown below. I have more information about these stages in this article about hardenability of steel.

Comparing Oils with the Inconel Probe Test

Below shows a range of different oil speeds from Houghton oils, as well as Canola:

Data adapted from Houghton International

The 7-9, 8-10, and 10-12 second oils look relatively similar but the peak cooling rates are slower as the nickel ball time goes up. The 15-22 second oil has a vapor blanket that lasts until a lower temperature, and then the peak cooling rate is significantly lower and at a lower temperature. Canola forms almost no vapor jacket at all and therefore reaches its peak cooling rate at a higher temperature. However, its cooling rate then decreases at higher temperatures, crossing over with the 15-22 second oil at about 1000°F.

However, if we look at water we see that it is much faster than any of the oils, coinciding with the nickel ball results I listed earlier. I have two temperature results listed because water is very sensitive to temperature. The closer the water is to boiling the more tenacious its vapor blanket is.

Water quenching chart from ASM Heat Treater’s Guide

However oil is much less sensitive to temperature. There are small changes in the cooling behavior with temperature but not nearly as extreme as water.

ASM Heat Treater’s Guide

Hardenability of Steel – Jominy

Hardenability of steel also has multiple measures. I first covered hardenability in this article which had an extensive discussion of different CCT curves (continuous cooling transformation) diagrams. Hardenability is how slow you can cool the steel from high temperature and still achieve full hardness. Hardenability is not a measure of how hard a steel can be after quenching, which is controlled by other factors, primarily how much carbon is “in solution” in the martensite. One relatively simple measure of hardenability is the Jominy test where a bar of steel is heated in a furnace and then is placed in a fixture with a water spray that is directed at one end of the bar. So that end is rapidly quenched and the cooling rate is progressively slower toward the other end, which is essentially being air cooled.

Comparing different steels you get a chart that looks something like this:

Adapted from ASM Heat Treater’s Guide

A2 is an air hardening steel so its line is flat; even with slow air cooling it fully hardens. 1095 is a water hardening steel so it only reaches maximum hardness at the position measured directly next to the water quench and the hardness drops rapidly. 5160 and O1 are oil hardening steels though the O1 is significantly more hardenable. 52100 is in between the water hardening and oil hardening steels, and different datasheets will recommend that either can be used depending on the cross section.

Continuous Cooling Transformation Curves

The CCT curves I mentioned above have more information about the behavior of the steel than the Jominy test. It is sort of like the difference between the nickel ball test (limited information) and the inconel probe test (more information). The CCT curve is generated by cooling the steel at different rates and measuring the phase transformations that occur during cooling. This shows the critical cooling rate required to avoid pearlite formation (makes the steel softer) and also the temperatures and times at which different phases will form. There are also certain features that can be different between steels such as some that will form some bainite (labeled B+K) if cooled at an appropriate rate, such as seen with O1 steel below:

Low hardenability steels see pearlite transformation at much shorter times such as can be seen with W2 below:

Different elements added to steel help to suppress the formation of pearlite. These elements are preferentially found in iron carbide so that when the steel tries to form the carbide phase of pearlite it is delayed by the diffusion of those elements. The most effective elements for hardenability are Mo, Mn, and Cr though Ni, Si, C, and V also affect hardenability. W2 has high carbon, low Mn/Si, and a V addition. The vanadium helps to refine the grain size which reduces hardenability (see my hardenability article). O1 has high Mn plus 0.5% Cr so it has relatively high hardenability.

Steels Used in This Study

I chose a range of low alloy steels to test the different oils that I bought. The primary tests I performed were with 1/4″ thick stock. 1/4″ is about as thick as most knives get so if it fully hardens at that cross-section then thinner knives will also work with that particular oil.

The steels above are ranked in order of increasing hardenability based on Jominy data, CCT curves, and otherwise estimated based on the composition using equations found in the hardenability article. W2 has very low Mn and Cr which means its hardenability is quite low. And as mentioned previously the vanadium addition refines the grain and further reduces its hardenability. 1095 has somewhat higher hardenability due to the increase in Mn. 26C3 has very high carbon which reduces hardenability, but the Cr addition helps to overcome that to have somewhat higher hardenability than 1095, at least according to the CCT curves. 26C3 has a similar high carbon+Mn+Cr composition to several steels like the Blue/Aogami series. 1084 is near-eutectoid and higher Mn than the previously mentioned steels which gives it increased hardenability. 80CrV2 has reduced Mn when compared with 1084 but with a significant Cr addition that makes up for it. 15N20 is an interesting case since it has a substantial Ni addition; nickel does not contribute that much to hardenability but 2% certainly has an effect. 52100 is a similar case with relatively low Mn but a substantial Cr addition for hardenability. CruForgeV and O1 combine significant Mn with a 0.5% Cr addition which is why they are the highest hardenability steels on the chart.

The W2, 1095, 1084, 80CrV2, 52100, and O1 were purchased from New Jersey Steel Baron. Most of the steels were produced by Buderus according to the composition sheets, and the O1 was produced by Latrobe. 26C3, 15N20, and CruForgeV came from Alpha Knife Supply. The 26C3 and 15N20 are produced by Uddeholm and CruForgeV is a Crucible product.

Experiment

I tested each of these as 1.5 x 2 inch rectangular specimens. The majority of the tests were with 1/4″ stock though some tests were done from 1/8″. The 1/4″ specimens were held at temperature for 18:30 minutes while the 1/8″ specimens were held for 10 minutes. Parks 50 and water were used at room temperature. The other oils were used at 120-150°F. I ground 1/32″ off the surface and tested the hardness, and then continued in 1/32″ increments checking the hardness each time until the center of the specimen.

1084 and Comparing Oils

It turns out that 1084 was in the sweet spot for comparing the different oils to each other; it shows the clearest differences. This was a little bit of a surprise because I expected 1084 and 80CrV2 to have more similar hardenability since Cr is less effective than Mn for hardenability, so 0.75 Mn should be similar to 0.4 Mn + 0.5 Cr. The results of the different quench media are shown below:

Water led to the highest hardness, as expected being the fastest quenchant. Parks 50 had a drop in hardness at the center of the 1084. Parks AAA had a maximum hardness of 62 Rc near the surface though it dropped to 60 Rc through the rest of the cross-section. Quenchfast (11 second oil) and Quenchol 521 (16 second) had somewhat odd behavior. The Quenchfast started out at higher hardness as expected but then the two oils crossed over at 3/32″ from the surface. I’m not sure what led to that result. The slow oil Quenchall led to low hardness. But the biggest surprise to me was that canola was by far the slowest oil. The overall time for cooling the steel in canola is very similar to the other oils, perhaps even faster. However, the slowing of cooling rate appears to be the deciding factor here. The “pearlite nose” on the CCT curve (the shortest time for transformation) occurs around 1050°F which is where the canola has already slowed down to the cooling rate of a slow oil.

O1 High Hardenability Steel

O1 with its very high hardenability there was no difference between Parks 50 and canola:

There is a small difference in hardness between the two oils shown above, however. This is likely due to “auto-tempering” which is a small amount of tempering that occurs by slow cooling through martensite formation. This explains why the two lines are parallel to each other rather than seeing a drop as would be expected from pearlite formation.

Water Hardening Steels – W2, 1095, and 26C3

I was also somewhat surprised that these water hardening grades did not fully harden in the Parks 50. Parks 50 is often promoted as “approaching the speed of water” but it turns out the word approaching is doing a lot of work in that sentence.

The other surprise here is that the steels are basically in reverse order of hardenability from what was expected on composition. I can’t think of many good reason why W2 with the lowest Mn is showing superior hardenability to the 1095, especially since both are made by the same manufacturer. I would expect the reason for reduced hardenability of 26C3 is because of differences in carbide structure from the manufacturer. Perhaps a follow-up study could be done where I dissolve the carbides and re-anneal them to all have a similar starting microstructure. When I quenched 1095 and W2 in water, however, they fully hardened. I didn’t have the 26C3 yet when I performed this experiment:

Effect of Cross Section with Low Hardenability Steels

Many knives are produced with thinner than 1/4″ stock so I was also interested in how much effect that would have. And some knives have bevels before hardening and so the edges may still harden even if the spine of the knife does not. Of course we expect a faster cooling rate with thinner steel and therefore better hardening.

Canola was unable to harden 26C3, 1095, W2, or 1084, though 1084 was by far the closest of those. I was surprised that canola could not fully harden 1/8″ 1084 since this is such a common oil used by beginning knifemakers. Parks AAA did harden the 1095 and W2 but not the 26C3, it needed Parks 50. Since the W2 and 1095 had higher hardenability than expected in my tests it is possible that other steel from another manufacturer, or the same steel hardened from the normalized condition may require faster than AAA. So for steels in the “water hardening” category I would recommend using water if thicker than 1/8″. Water can be a dangerous quenchant, it is important to avoid stress risers in the knife and keep the grain size small in the steel. Also “hard” water is a faster quenchant than distilled. If 1/8″ or thinner it appears that a very fast oil is effective in these low hardenability steels.

Intermediate Hardenability Steels

80CrV2 and 52100 had somewhat inconsistent hardening results. I believe this is also due to prior microstructure effects. Perhaps if the steel was processed for a finer microstructure in the annealed condition it would show more consistent hardness at the surface with fast oil. A finer microstructure would also reduce the hardenability of the steel so that could be an interesting follow-up as with the 1095/W2. With 80CrV2 the canola did not fully harden the 1/4″ steel and Quenchall was about 2 Rc lower than the other oils throughout. With 52100, canola and Quenchall dropped a couple Rc by the surface which makes it appear that the oils are not fast enough for that cross section. However, with the inconsistent hardening, Parks AAA and Quenchol 521 had somewhat lower hardness at the surface than the center. So it is hard to tell if the canola/Quenchall are insufficiently fast.

With 15N20 the Parks 50 (fast) and Quenchfast (medium) oils behaved similarly, while canola clearly led to softer steel. For CruForgeV all three oils showed similar results, so it seems to be hardenable enough that oil doesn’t matter too much with 1/4″ thickness.

Quenching Too Fast?

A frequent discussion I see on the forums and Facebook groups is whether to use Parks 50 or AAA for a particular steel. These oils are common with knifemakers so it is often a decision between one or the other. Some knifemakers will say that Parks 50 is “too fast” for some steels and you must switch to AAA to avoid reduced toughness. However, this is not as important a decision as is sometimes stated. One thing to remember is that Parks 50 and AAA are not that different from each other; this is not a decision between a very fast and very slow oil. AAA is straddling the line of the fast oil category.

One of the concerns is that the faster oil leads to microcracks and therefore reduced toughness. Microcracks are real but they occur due to plate martensite formation not from overly-fast quenching. Plate martensite comes from very high carbon austenite so this is controlled by austenitizing (how much carbon is in solution) not from quenching.

In a previous study we did on 8670 toughness we looked at toughness differences between Parks 50 and AAA. 8670 has hardenability similar to CruForgeV and is one of the steels that is sometimes said to be a no-no for Parks 50. However, the toughness was the same whether we used Parks 50 or AAA, in fact the Parks 50 was slightly higher but that is probably just due to experimental scatter.

Instead, the concerns with quenching more rapidly are warping and cracking. Cracks are not the same as microcracks. Microcracks are a microstructure-level feature that specific etching techniques are required to reveal. Cracking is on a macro level and are much more obvious. High hardenability steels can be quenched in slower oils to minimize the chances of warping and cracking. However, quenching high hardenability steels in a fast oil is still possible and it doesn’t mean reduced toughness.

Which Oil to Buy? 

Because warping/cracking can be reduced through a slower oil it makes sense to have multiple oils depending on the hardenability of the steel. However, if you buy only one oil it should be a fast oil like Parks 50 so that you can quench the low hardenability steels. If the funds are really so tight that you are considering buying canola I would recommend getting the relatively inexpensive AAA instead.

Which Steels Can be Quenched in Slower Oils?

To know which steels can be used with slower oil to minimize warping/cracking I have the following chart that is from my book Knife Engineering. It is an approximate ranking based on hardenability. The steels at the top are expected to have the lowest hardenability and the bottom has a few air hardening steels as examples.

Summary and Conslusions

The biggest takeaway for me is that canola is not a particularly great quenchant. I would highly recommend buying a commercial quenching oil instead. I was also a bit surprised just how sensitive the water hardening grades were to cross-section and oil. I thought at 1/8″ they would harden no problem. There was a pretty sharp transition where 1084 was a step up in hardenability from 1095/W2/26C3, and then every steel with higher hardenability than that was basically insensitive to oil choice. A few potential follow-up studies were mentioned in this article, such as processing the steels for different prior microstructures. We would expect normalized steel (pearlite) or fine carbide annealed structure to have reduced hardenability, which may be significant for forging bladesmiths. The austenitizing temperature can also affect hardenability, typically low temperatures lead to reduced hardenability. And of course we can look at other steels where we think it will be interesting.

[1] Pérez-Ruiz, Eduardo, Santiago Frye Rocha, and Jorge Freddy Llano Martínez. “Performance of Vegetable Oils on the Hardness and Microstructure of AISI 1045 Steel Quenched.” (2019).

The post Which Quenching Oil is Best for Knives? appeared first on Knife Steel Nerds.

Hola a tod@s !! Tenía una duda... Tengo una estructura de hierro forjado para un acuario de 212 litros y mi duda era si al no llegar a cubrir toda la base, podría aguantar el peso del acuario según está en la foto? Muchas gracias

Used to get 3/16 steel rod for model boat propeller shafts. Was able to easily drill 1/16 hole and thread 10-32. All rod available now is too hard to drill or tap. Not sure what it was that I bought in the past that was so forgiving.

Last reply by randomnobody on Sun, 11 Jul 2021 19:28:09 +0000

Last reply by soulfromheart on Sun, 11 Jul 2021 19:19:31 +0000

Glad to be here! I have already seen some glorious things going on and maybe I could add a little to the scrap pile (but preferably the "keepers" pile.)
I first got my fingers burned many years ago in the UK. Took up residence in Canada 45 years ago and have been in and out, mainly out, of casting work since I landed. Somehow it never really leaves your blood if you follow. Nothing quite like the smell of burning Petrobond in the morning I guess!
I have long had a hankering for making Art...

Another lad from Ontario

I built my first furnace back in 2012, and have experimented with oil and propane burners ever since.

I melted aluminum first, and that was pretty easy. You can melt aluminum as easily as Zamak (in my opinion) using the same propane burner and just slightly more heat.
Zamak has more mass to it.

I really wanted to master pouring gray iron, and that took a figure out.
If you know what you are doing, casting gray iron is not much more difficult than casting aluminum, although there is a lot...

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