Care to comment on this video?

[element]

YouTube - Jominy End-Quench Test


Interesting, But does it all make sense? Does anyone harden steel like that? Or its not something very practical for the average joe?

[archiphile]

I think that it was just meant to check the hardenability of a particular batch of steel for use in shop. Q.C. guys you to test samples like this all the time.

[Frosty]

It's a lab test aimed more towards repeatable and consistent conditions than practical application. We did a lot of this kind of thing in the soils lab. Tests that bore no resemblance to practical application but bore meaningful results to design field methods with.

This particular test appears to demonstrate the different properties achieved by different quench speeds. I assume the water is held at a specific temp, most lab tests spec "room" temp. 70f unless chilled or warmed is called for, then the specific temp is speced. It would also spec mineral content, labs typically require distilled unless specifically called out. In some cases we'd test with local well or river water collected using speced techniques.

It goes on and on. The more important the data the more every aspect is speced.

Frosty

Edited March 27, 2009 by Frosty

[TASMITH]

That is a certified test for the hardenability of steels. It is used in research labs all over the world and is an industry standard. This type of quench is different than putting a piece of steel in a tank of plain water or even superquench. There is a constant flow of water against the end of the bar with no chance of steam formation due to the water constantly being refreshed and a a large flow rate in comparison to surface contact. It cools the end of the steel far quicker than any other quench method could thus giving a high RC value at the front quench edge. You will note however that the hardness drops off quickly even though the bar was quenched for 10 minutes in the water. This is typical of a plain low carbon bar. The hardness tester used in the video is highly accurate.
It is the same type I used when checking the tool steels I used to heat treat.

That method of end quenching has been used for years in the blacksmithing trade on the face of hand hammers. It gives a hard face with a tough interior for shock resistance. We used to do this with a brand of steel made by Atlas steel called Alpha 8. It was a water hardening steel but we used to just end quench the face of the hammers we made for the same reason. Hard surface face, but a tough core. They used to stand up extremely well.

Terry

[element]

Thats cool thanks guys, that cleared alot of questions.

I was hoping someone would mention hammers because thats the main reason i brought this video up.

TASMITH, how did you harden the two faces of a hammer at the same time? Like a ferriers hammer for example or a cross peen.I have yet to find this information. I did however find some old text that sayd quench one face for x amount of time flip it and quench the other face, Let the colors run to the first quenched face( purple i presume) and then full quench until completely cool. Id love to hear more of your hammer making experience! I am absolutely all ears because making hammers and sledges is one of my next top priority. If Anyone else want to bite the bait that would be much apreciated.

Eric

[TASMITH]

Element;
When quenching two faces on the same hammer we used the cool and switch method. It is a little difficult to do because you have to keep sufficient heat on both faces to get maximum hardness on both faces, but at the same time not let the first face heat too much while quenching the second. we used to flip back and forth between the faces until the centre mass of the hammer had cooled to the point that the residual heat would more or less temper both faces evenly. It is something that takes practise and good judgement of remaining residual heat in the centre mass. If done correctly you have a hard tempered face and a tough core in the hammer.

to quench the face you need to use the same method as shown in the video with the water coming up against the face. This ensures that you are not quenching the main body of the hammer with the water, but maximizing the cooling of the face. This is almost like differential hardening in a way and works well with the proper steel.

[Quenchcrack]

The Jominy end quench test has been so well documented over the many years it has been used that, today, the results can be accurately calculated from the chemistry alone. As TASMITH points out, this test is designed to generate a curve of the hardness vs depth in a quenched steel. This is used to determine the hardenability of the steel. Also see BP 0078 for further explanation.

[element]

Ok ive read bp0078 and it seems alloys are better for hammers. I have a few pieces of drive shafts, I assume its 4140 but not sure,so il take a piece like 4 inches and practice hardening two ends with the cool and switch method. How does this sound? After the hammer is forged and normalized, couldnt you just put a clay coat all around the hammer except the face and peen? Let that dry up a few days and heat and quench the whole hammer head.

[Frosty]

I used a pickup truck axle. I hardened it fully and tempered by inserting a hot drift in the eye till the colors at the face were what I wanted, dark tan and a tad softer than I would've preferred but it's plenty good.

If one face hits your temper color before the other it's easy to quench one face while continuing with the hot drift heating.

It's a rather slow process but worked fine for me.

Frosty

[element]

Thanks for sharing frosty, Your method seems to work good. Il try that way also in the near future. I guess the key is finding what works best for yourself and practice practice practice....

[Frosty]

I like how it works, I don't have to react is a split second and (this is my feeling I have no evidence) I think the temper heat soaks deeper and is more effective.

The pics show my hammer head as tempered.

Frosty