Recommendations for Small Heat Treating Oven

[1953chevB]

yes carbon steel will case to but not as deep, carburizing steel are expensive so have to take into account

 

[SobtzakTech]

1953ChevB,
You work with gas to carbonize parts. I believe my oven can be equipped with a flow meter for that. Do you know were I can get more info on using gas? Types, flowrates, times, etc?

 

[SobtzakTech]

Ok, so I guess I should ask this question......I could either make these parts (teeth for compact tractor toothbar) from mild steel and case harden them, or I could make them from say 4130 and do normal hardening. Any feel for which may be cheaper?! I thought case hardening may be cheaper, plus a little easier on the end mills when milling but I may be wrong.
If I do case hardening, any recommendations for compound? I've seen a lot for Cherry Red. That's where you pull the part out hot and dunk it in it, correct? That stuff work ok? Or, again, I could try charcoal and bone char. I don't care about the finished color. Just trying to find low cost method and material.

 

[SobtzakTech]

you may need two ovens

In case not aware , FYI low alloy steel heat treating
to hold hardness 30-35 HRC has to austenitize , quench & temper, temper must be with in one hour or it will crack
austenitize temp = 1650-1700 deg. F
quench in oil or water (I recommend oil less distortion)
then temper at oil -1050 +/- 25 Deg. F , water = 1100 +/- 25 Deg. F
see ref link : AISI 4130 Alloy Steel (UNS G41300)

to anneal = 1515 +/- 25 Deg F then air cool

1953chevB,
I forgot to respond to this. I appreciate the info. I'm aware of the process of going from perlite to austenite and then martensite, then tempering to change the carbon 'needles' in the martensite. I'm just not experienced with actually doing it so I really appreciate the numbers, i.e. temperatures, times, etc. THIS IS WHAT THEY DON'T TEACH YOU IN ENGINEERING SCHOOL!
Also, I followed your link to AZO Materials. I like this site! Look up any metal and get the specific temperatures you need. Thanks a bunch!

 

[1953chevB]

Ok, so I guess I should ask this question......I could either make these parts (teeth for compact tractor toothbar) from mild steel and case harden them, or I could make them from say 4130 and do normal hardening. Any feel for which may be cheaper?! I thought case hardening may be cheaper, plus a little easier on the end mills when milling but I may be wrong.
If I do case hardening, any recommendations for compound? I've seen a lot for Cherry Red. That's where you pull the part out hot and dunk it in it, correct? That stuff work ok? Or, again, I could try charcoal and bone char. I don't care about the finished color. Just trying to find low cost method and material.

see post #18 at the bottom I added an edit with the correct procedure for pack carburizing.
far as the tooth bar is that on the back scraper of the tractor?
if so I was reading up on that the other day, the teeth I read some were that it's better at medium hardness, so they wear evenly,
can you google that I found it once for my ford 8N tractor, I need a new blade, for that application I believe they use 1095 carbon steel
through harden to 40 HRC.I believe from memory, so do some more research from this lead.
carburizing is mostly but not all for bearing journals and gear teeth, for wear & where the hertz hardness has to be high on the hardness.

far as ovens go it's best to contact manufactures of the ovens, hold on to your hat, but they do make smaller more affordable simpler oven.

 

[1953chevB]

1953chevB,
I forgot to respond to this. I appreciate the info. I'm aware of the process of going from perlite to austenite and then martensite, then tempering to change the carbon 'needles' in the martensite. I'm just not experienced with actually doing it so I really appreciate the numbers, i.e. temperatures, times, etc. THIS IS WHAT THEY DON'T TEACH YOU IN ENGINEERING SCHOOL!
Also, I followed your link to AZO Materials. I like this site! Look up any metal and get the specific temperatures you need. Thanks a bunch!

thank you yep it's from years of experience.

 

[gbent]

Carburize for earth wear parts will be quite unsuitable and much more money than necessary. For a very low budget solution I would use mild steel and hard face. For a better solution I would use whatever version of AR steel I could get cut to shape and hard face. Real earth wear parts would be a very hard cast iron, something with long wearing alloys such as chrome carbide, and easily replaceable because no matter the material, they wear out.

 

[john.k]

GB is right.......for dozers and the like ,ripper tynes ,blade edges ,blade skins,etc are often made f rom one of the HSLA type "wearplates" and simply plasma or oxy cut from the plate ........for a smaller tractor ,that may not have much tractive force ,then low carbon steel may be OK ,with wearing /worn parts built up with weld hardfacing..........The hairiest stuff for big dozers is nearly always cast steel ,of a very tough and hard nature,and heat treated to withstand the massive loads.....A big dozer can turn granite rock into puffs of smoke with a ripper.

 

[Gordon Heaton]

Hi SobtzakTech. I got your PM and replied before catching up on this thread. My reference at the beginning to the inerting atmosphere on the Paragon is just that, reduction of oxygen to minimize or eliminate scaling and decarburization. I've never attempted gas hardening and I don't think the Paragon would be a good candidate for that since it doesn't seal up tightly. It relies on a constant inflow of gas to equal the leakage.

 

[1953chevB]

are talking about like this
Sub-Soil Ripper

 

[SobtzakTech]

1953ChevB - I appreciate the info. I did basically exactly what was described in post #18. I pack carbonized in a box in the oven with a commercial compound. Had to post-heat treat since you can't get them out of the box until they cool so they basically get annealed. After hardening and tempering, they came out really nice. They have a good hard case to I'm guessing 0.040-0.050"
These teeth are for small compact tractors. The teeth themselves are small as noted, triangular shape with base being 3.75in, hieght being 2in. So they're not for super heavy duty operation. They can also be easily replaced. Hence, I thought I'd try case hardening.
I've just found that the compound isn't very cheap. I know you can re-use it when mixed 50/50 with new stuff. I'm still experimenting and wondering it I can find a cheaper compound to use like bone char and basic charcoal but I know I won't get as deep as casing. Other options are to a) as others suggest, weld a surface onto them or b) Go to a harder alloy. Just seeing what everyone thinks. Feedback has been great. Thanks a bunch!

 

[1953chevB]

1953ChevB - I appreciate the info. I did basically exactly what was described in post #18. I pack carbonized in a box in the oven with a commercial compound. Had to post-heat treat since you can't get them out of the box until they cool so they basically get annealed. After hardening and tempering, they came out really nice. They have a good hard case to I'm guessing 0.040-0.050"
These teeth are for small compact tractors. The teeth themselves are small as noted, triangular shape with base being 3.75in, hieght being 2in. So they're not for super heavy duty operation. They can also be easily replaced. Hence, I thought I'd try case hardening.
I've just found that the compound isn't very cheap. I know you can re-use it when mixed 50/50 with new stuff. I'm still experimenting and wondering it I can find a cheaper compound to use like bone char and basic charcoal but I know I won't get as deep as casing. Other options are to a) as others suggest, weld a surface onto them or b) Go to a harder alloy. Just seeing what everyone thinks. Feedback has been great. Thanks a bunch!

Your Welcome

 

[john.k]

From the description of the teeth,no way would I muck about with hardening....just build them up with hardfacing rod on the wear surfaces ......if the teeth bend ,then have them cut from a HSLA steel ...called Wearplate.....but I dont think this will be needed for a garden tractor.