Goran Hosinsky | 04/10/2010 15:48:43 |
41 forum posts | The silver steel that Chronus sells, should I use water or oil to quench it? Goran Canary Islands |
mick | 04/10/2010 17:38:48 |
421 forum posts 49 photos | Hi.
Dosn't much matter who supplies it, its still quenched in cold clean water, although it will still take on hardness if quenched in oil, but not to the same degree. I've heard of old engineers who would quench in a container of oil and water. The oil floating on top is the first quench and then the water beneath completes the job, its supposed to harden and temper in one go, although I've never been brave enough to try it! |
Dusty | 04/10/2010 17:53:53 |
498 forum posts 9 photos | Goran
The oil and water trick is good and works, but it will not harden and temper in one go. The oil which should be about 6/8mm thick is to help prevent cracking the shock of plunging small sections into cold water can cause stress cracks to appear. Usually the first you know about them is when the component falls apart. For most items I use a jar of about 500grams capacity. The glass jar allows you to drop the item to be hardened into the jar and being glass you can see it to recover it. |
Tony Pratt 1 | 04/10/2010 18:25:57 |
2319 forum posts 13 photos | A water quench will give you maximum hardness and also maximum brittleness, an oil quench will give you a slightly less hard component but not by much. After hardening the job will always have to be tempered to suit the components application.
I have never heard of the oil/water combined quench or seen it mentioned in any of the tool steel manufacturers heat treat specifications and I imagine the benefits are a bit of a myth and more imagined than real.
Tony |
macmarch | 04/10/2010 20:06:42 |
147 forum posts 1 photos | When I was an apprentice, way back in 1900 and frozen to death, we were trained to water quench silver steel and gauge plate but oil quench tougher grades like EN24 and the like. Perhaps someone has an ancient copy of Kemps or an old treatise on hardening circa 1950. When I started to H & T at home there were times that cracking became apparent. I have now changed my method of tempering and have not since had any problems that I am aware of. After hardening and cleaning I temper in the electric oven. I find that a good half hour plus a minute per 10 thou of thickness does the trick . It is satisfying to see the required colour all over the part. It enables the grain structure to realign after the surface shock of quenching. I have found that 'most' people heat to cherry red then quench when the cherry red stage should be held for some time to allow the grain to adjust all the way through before quenching and then the tempering temperature! held for the same reason.
Is there someone here that could give a simple explanation of the Iron/Carbon Diagram for the benefit of the newer members to the craft.
If you are a person that changes the own engine oil then keep some next time. When a mild steel compenent has to used outside then heating to a dull red then dropping in the carbon rich oil won't harden it but it will give it long lasting protection against rust. Just don't try welding it after.
ray |
Jens Eirik Skogstad | 04/10/2010 20:56:24 |
![]() 400 forum posts 22 photos | Water must be some days old to be sure the air are disappeared from the water to give good conduct of cooling of the part who are quenced. After the part are in the water, move the part around in the water to be sure the water are not heated by the part who are hardening.
In case you has a part who has a thinnest part and the thickest part, begin first with thinnest part then rest of the thicker part while you are quencing the part. |
Andrew Johnston | 04/10/2010 22:13:02 |
![]() 7061 forum posts 719 photos | A rule of thumb I use for hardening carbon steel is to maintain the hardening temperature for an hour per inch of thickness. Ideally one should quench in brine, rather than plain water, as this inhibits the formation of bubbles at the interface with the hot metal and hence improves the cooling. Regards, Andrew |
ady | 04/10/2010 23:22:25 |
612 forum posts 50 photos | Canary Islands? Dunk it into a volcano on the end a rope, use water to quench. Read up on hardening and tempering on the net, there are some good resources. |
John Olsen | 05/10/2010 05:15:22 |
1294 forum posts 108 photos 1 articles | The Canary Islands are I beleive surrounded by a convenient supply of Brine. regards John |
Goran Hosinsky | 05/10/2010 08:24:15 |
41 forum posts | The brine we have yes, and the volcano. Just two small problems. One is the distance as the volcano is at about 8000 feet and the brine at 0 feet, the distance in time I do not really know as the road is very curvy. Second problem is my supply of quality rope which will stand the heat ... Ray, at what temperature do you run the oven? I have read in some publications that there are two types of silversteel, one which should be quenched in oil and one type that should be quenched in water, that is why I asked. Thanks for the clarifications! Goran |
ady | 05/10/2010 08:39:22 |
612 forum posts 50 photos | I don't know about temperatures, they tend use a lot of colour descriptions. 'Straw colour' was one I read about a lot. One article I read had them only quenching with a quick dunk in brine, to harden the outer skin, then leaving the hot steel item on a cool concrete floor to temper. I think it was a motor bike part which kept failing, that part never failed again after this approach. An interesting subject. |
macmarch | 05/10/2010 09:44:28 |
147 forum posts 1 photos | The colour you temper to is determined by the use the tool is put to.
Assuming standard silver steel. (should have "Stubbs" marked on one end.
Oven Temp
Brass turning tools 180 C
Lathe tools 200 210 C (and chisels)
Milling cutters 220 230 C
Scrapers 190 200 C
Springs Flat out
By colour
Pale straw 190 200
straw 210 220
dark straw 220 230
For things like cold chisels and screwdrivers take them out of the oven and give a blast with a gas torch to get a little blue at the tip and plunge immediately.
I had a word with an old friend (85) and I quote,
" Quench in brine for a faster cool down. Quench in oil hardening oil but only if the silver steel is specifically an oil hardening type. The brine shoud be rock salt or other form not table salt as it has additives that can alter the material. Use a solution of about 10% salt. Don't forget that as you have cooled down a lump of overheated steel it will have all sorts of stresses in it so the slower and longer the heating and holding at the right temp during tempering the better."
HTH
PS If swimbo allows you can also use the chip fryer. BUT MAKE SURE their is NO WATER on the parts.
As I was writing this I have been advised that Tubal Cain's book WPS1 covers this subject in great depth. Edited By macmarch on 05/10/2010 09:46:37 Edited By macmarch on 05/10/2010 09:49:03 |
Andrew Johnston | 05/10/2010 09:55:59 |
![]() 7061 forum posts 719 photos | I second the recommendation of Tubal Cain's WPS1 book. It explains a complex subject in sufficient detail to allow proper hardening and tempering of carbon steels in the home workshop. Regards, Andrew |
jomac | 05/10/2010 11:36:01 |
113 forum posts | Hi, I need enlightening, (no dieting). Keep doing and not thinking works for me. John Holloway, (now living in Oz for the last 60 plus years) |
Andrew Johnston | 05/10/2010 11:53:14 |
![]() 7061 forum posts 719 photos | I don't know for sure, but the second biggest constituent of urine, after water, is urea. Urea contains nitrogen, and gives off ammonia when in contact with water. That might explain the nasty niff. Perhaps it was a early form of nitriding? I don't have a lemon tree in the garden, but I have been known to micturate on the compost heap, rather than traipse back indoors when caught short. Regards, Andrew |
Stub Mandrel | 10/10/2010 21:38:04 |
![]() 4318 forum posts 291 photos 1 articles | I met David Bellamy, He spent a long time discussing peeing on the compost with a colleague ![]() Neil |
Ian S C | 11/10/2010 10:10:48 |
![]() 7468 forum posts 230 photos | In the days of gunpoweder, nitrate was extracted from urine for use in the manufacturing of gunpoweder. I read of it some time ago, not sure if it was on the web, or there was an artical in ME. Ian S C |
Stub Mandrel | 11/10/2010 19:25:18 |
![]() 4318 forum posts 291 photos 1 articles | To return to the question (for once!), I use water to quench Chronos silver steel and rapeseed oil for the gauge plate and I haven't had a duff result or a crack yet. Neil |
Sam Stones | 12/10/2010 02:20:14 |
![]() 922 forum posts 332 photos |
Gentlemen,
I couldn’t resist `chipping’ in with a couple of comments.
I would go along with most of what has been mentioned, although I always use clean cold water for quenching silver steel and gauge plate. Both are high carbon steels, (above the eutectic of 0.87% carbon). Lower than this amount of carbon, the more difficult to impossible it is to reach a satisfactory hardness result. That’s why mild steel has to be carburised to achieve any kind of additional hardness. For those (beginners) not in the know, this is known as case-hardening. I have used Kasenit(?) for many on my MS parts, and always got good results.
For the technically inquisitive, I recall that there’s something about the carbon atoms shifting between body-centred and face-centred, but I can’t remember which way round.
If you don’t temper after hardening these steels, you should anticipate a high level of brittleness. Curiously, the smallest bearings in the skeleton clock (referred to as jewels), are left `dead’ hard. But with an OD of 3/32", an ID of 0.025", and a length of 1/8", they are not under much stress. Now, as for cracking. What about mentioning notch-sensitivity, and the reason for radiusing inside corners? With more than 40 years experience in the plastics industry, I can assure you that sharp corners (notches) are very much the cause of (apparent) brittle failures in plastics components. These stress-raisers are one of the reasons plastics get their bad name. Ask a reputable toolmaker to leave sharp notches in any part of his tooling which is subsequently due for heat treatment, and he should look at you askance. Yet have a close look at any plastic component which has broken, and I could almost guarantee, you’ll find a sharp notch where the sharp (external) edge of a mould has been overlooked. I thought the Japanese quenched their swords in ox blood? Regards to all, Sam
One hundred postings - Time to celebrate!
Edited By Sam Stones on 12/10/2010 02:21:50 Edited By Sam Stones on 12/10/2010 02:23:02 |
Stub Mandrel | 12/10/2010 19:58:15 |
![]() 4318 forum posts 291 photos 1 articles | > quenched their swords in ox blood? I don't know, but I harden my cutting tools by heating them to the colour of the rising sun, and test them by cutting a peasant in half. Neil |
Please login to post a reply.
Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!
Sign up to our newsletter and get a free digital issue.
You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy
You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.
Click THIS LINK for full contact details.
For subscription issues please see THIS LINK.