Welcome to ModelEngineMaker !If you have problems registering or logging in, please use the contact menu option to request assistance.
There are lots of old school methods About 60 years ago a friend of my dads ( both passed now ) made very very good 2 1/2 gauge locos and I mead rivet perfect ( this is before cars were common and locos were taken to the track on the back of a motor bike ) Anyway back to the plot he case hardened all the motion and the polished it to a good finish , he used to pack the part in a tin (baccy tin for the small bits ) with bone meal ( ground up animal bone used for garden fertiliser ) and put it in the coal fire before bedtime ,fetched it out in the morning , reheated it to red and quenched this gave it a long soak to get the carbon it Leather also works , as does any thing that has carbon in itBut times were tough then some cheaper method were used , but a good old powder mix was better Btw I was a young 11 years old then but I had been interested in making stuff before then
The 8 hour soak is one I remember as well, and an overnight soak in a damped fire was the method Dad used...This was always a good reference, but there is also a fair bit of info. in Machinery's Handbook on the hardenability of steel. A36 is pretty close to 1018 in hardenability.https://www.emjmetals.com/pdf_indexer/pdfs/Mechanical_Properties_and_Hardenability.pdf
Hello Thomas - I have been AWOL for a while and have only just read your thread.I have had a fair bit of experience in heat treating tool steels and have done a small amount of case hardening - this is both at work and play.With case hardening as has been said the longer the part is in contact with the product - Kasenite, Cherry Red, bone meal etc etc the deeper the 'skin' of the hardened surface. To have anything considered effective this would need to be held at temp for some time - hence the advice of packing the part and material in a container and soaking over night in a fire. Given however you just wish to put a hard surface on the the following should give you what you need. Put some of the Cherry Red powder into a container that the part can be placed in. Heat the part to a good bright red and lay the part into the powder turning it to coat it where you want the hardness. Remove and reheat letting the heat really soak into the part - lay it back in the powder and repeat. It is a hot and smelly process and the part takes on a pretty miserable looking surface blistered and misshapen. That will disappear as soon as you quench it. Keep the heat up and when you are satisfied that you've given it enough treatment quench it - quickly - in clean and quite cold water. I stress that as it's important to get a good result. As said you need to plunge the part into the water really quickly and if Cherry Red responds the same as Kasenite you will hear a sharp crack as it hardens. If you find it has not hardened then reheat to a slightly hotter temperature but importantly change the water - as clean cold water will always give you the best resultsHope that is of help to you - it should give you what you are wanting.Regards - Tug
Hi again Thomas,I cannot see that that would make any difference on 'home' methods other than to stress relieve the part. If you have made it from hot rolled steel as you state as opposed to CRS then what little stress that may be in the part should dissipate in the heat treatment.Something I would add however is that whilst as said it's best to plunge the part into the water as quickly as possible it needs to be as 'evenly as possible' to eliminate any chances of uneven/unequal cooling creating distortion.Good luck with your project Regards - Tug
Hi Thomas,Please note I've added a post script to my last post which you may not be aware ofTug
I have a small part of mild steel for the clutch I am building out for heat treat (case hardening) right now. The person who is looking after it for me is a master machinist with 40 years of experience. I asked him about the idea of me buying the Casenite and case hardening the part myself. He just laughed and said that the amount of depth from a home grown case hardening was very, very little, and not uniform. He sends batch lots of parts out for case hardening to a professional heat treat facility, and tells me that a home brewed case hardening didn't even come close to what would be acceptable. Anything I wanted hardened previous to this was made form 01 steel, heated orange/red and dropped in a container of oil, then 'drawn back' by heating in my wifes kitchen oven for a couple of hours at 350 degrees so it wouldn't be brittle. Not very professional at all, but it does work for me.