Jump to content
I Forge Iron

I was asked at work to harden EN24 . Looking for advice how to do it. Thanks


Recommended Posts

First i need to say this is my first time doing this or attemptiong it, hence all the questions.

I was asked at work to harden EN24t its a part for a rolling mashine that another worker milled out . there is 6x in total they were using these already but decided they want to get them harder, so they can last longer.

Could you give me advice how to harden it?

(I am using a gas forge for this) from topic (problem with forge. Welding temp)

I would heat the steel to 820/850°C how long i should keep in in the forge for? 

do i just quench in any oil? or sould i use something specific

then the tempering : what temperature sould i temper it? or should i temper it at all? these wheels are used in rolling mashine for rolling a 60/40mm mild steel box section 3mm thick

 

thank you guys for any advice.

20210604_143911[1].jpg

20210604_143840[1].jpg

Link to comment
Share on other sites

you are talking about 2 different things here.  Work hardening does not involve heat, which is your title, then you ask about heating and quenching which will undo any work hardening you put into it

Link to comment
Share on other sites

I am no expert but have been around machine tools for a while.  It may not be the appropriate method of hardening you are presently thinking.  There are methods like flame hardening which will harden just the surface to make it much more wear resistant while retaining toughness.  Pack carburization is another method.  Have you a mettalurgist or materials person to consult with?

Link to comment
Share on other sites

Work hardening is done COLD by plastic deformation like hammering or bending and any heating to above the dislocation climb temperature will cause it to go away.

Case Hardening is done hot using a compound that increases the carbon content of the surface of the steel allowing it to harden when quenched.

Regular hardening in heat treat is done with alloys of steel that will harden when heated and quenched in various ways. 

Note the two involving heat don't require welding temps!

I see that EN24t is a medium carbon steel; I would ask the company that supplies it to you to provide a copy of their heat treating instructions and follow them as far as normalizing, heating above critical, quenching and tempering.

Link to comment
Share on other sites

I was asked at work

If i could harden them flanges made out of EN24t

sorry for any confusion

i only have a gas forge to work with and just dont want to mess it up.

Link to comment
Share on other sites

As I said ASK THE SUPPLIER!   They should be able to provide data on how to heat treat it.  If not them look it up in a good metals heat treating handbook.  I use one put out by the ASM; but I am sure there are similar ones available in the UK.

Link to comment
Share on other sites

If this is a critical component and you are concerned about missing it up, I would think twice before you stick your neck out and try to heat treat it with a forge. Most blacksmiths can get away with playing it a little fast and loose with hardening temperatures/soak times/manufactures specs because of the nature of how most of our tools are used. 

Even professional blade smiths will sometimes send their blades out for heat treatment. Or at the very least they invest in a heat treat oven. 

If the part fails and the rolling machine is damaged or worse, an employee is injured because you went with the cowboy method rather than a controlled process, I don't think the end results will be favorable for anyone.. I think it's fair to say if you don't know what oil to use or if you should temper it, you probably shouldn't be heat treating it.

I'm not trying to give you a hard time, I'm just saying I wouldn't bring that thing anywhere near my forge.. Too much liability.

Link to comment
Share on other sites

I certainly would not agree to harden them. If they want it done, just have them send it off to a heat treatment shop. It's not worth risking the part failing in use and damaging expensive equipment or causing an injury.

EDIT: Frazer beat me to it

Link to comment
Share on other sites

At our facility, we have very specific requirements for roll form wheels. Not my area, so I don’t know the specifics, but they are all hardened and most have additional surface treatment. In the past the surface treatment was TD coating (high temperature thermal diffusion of Vanadium Carbide into the surface layer, produces a very high surface hardness, but the polishing operation is very critical to longevity.) I can’t really offer much more, but to get really good life out of roll wheels, they really need to be looking at a professional service. While expensive, the return on investment is quite significant.

David

Link to comment
Share on other sites

thanks guys a lot of usefull information. I will let my bosses know and i can imagine they will probably go with the coating on them. the supplier does not provide heat treatment information hence my questions before. Thanks a million for all of your replies

Link to comment
Share on other sites

EN24 is a very high strength steel alloy which is supplied hardened and tempered. The grade is a nickel chromium molybdenum combination - this offers high tensile steel strength, with good ductility and wear resistance characteristics.


EN24 is a very popular grade of through-hardening alloy steel, which is readily machinable in the “T” condition. (Refer to our machinability guide). EN24T is most suitable for the manufacture of parts such as heavy-duty axles and shafts, gears, bolts and studs.  EN24T can be further surface-hardened typically to 58-60 HRC by induction or nitride processes, producing components with enhanced wear resistance.

In addition to the above, EN24T is capable of retaining good impact values at low temperatures, hence it is frequently specified for harsh offshore applications such as hydraulic bolt tensioners and shipborne mechanical handling equipment.

https://www.smithmetal.com/pdf/engineering/en24.pdf

Link to comment
Share on other sites

EN24 in the states is known as 4340. 

If your supplier does not provide specs for how to work the material, change suppliers. Each suppliers steel will work a little different than another. This is true, trust me, i work with a cheap skate GM that bounces from supplier to supplier depending on price. Right now i am making these little pins that are knurled on one end. Changed lots of stock and the new stock was wiping out the knurling tool in less than 3,000 parts. Had to change the feed rate for that particular steel to keep my knurls working good. And cobalt knurls are not the cheapest things, they kind of frown on going through a dozen knurls a week. Just an example of how different suppliers steels work and machine. 

I myself would tell my work "NO" in great big letters too. The reason is liability. There are places that specialize in heat treating that have all the modern equipment  to heat treat and the lawyers to take care of any liability claims. You have a gas forge and a bucket of oil, if the piece happens to crack and that crack leads to someone's injury i could see a good lawyer taking you and your employer to the cleaners over it. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...