4150 "toughness"

[marmon]

i have some 4150 and i need to heat treat them for maximum toughness. What Rc value is this at? I assumed 50, but i recieved the parts back at 60+. Is it possible to anneal them without sacrificing the material? Is there any other way to bring them back to the 50 level? What is a good definition of "toughness"

 

[metengr]

Toughness is basically the resistance of a metal to crack propagation. Normally, toughness is optimzed by sacrificing strength (or hardness) for most carbon and low alloy steels. The minimum level of toughness is established based on application. What is the application of this material?

 

[TVP]

marmon,

While we await your reply to metengr's question about the application, I will add that the maximum toughness of 4150 occurs at a hardness much lower than 50 HRC and yes, it is possible to temper this grade at a higehr temperature in order to reduce the hardness from 60 HRC to ??? HRC.

 

[marmon]

It is for a chain roller application. The chain is a heavily abused sharp chain. I am not to concerned with wear as the chain is replaced bi-annualy.(it is usually destroyed before any wear is evident). My choice for 4150 was that it was readily available and it came in turned and polished form. In stock form the 4150 had a low Rc number as what was desired, so to get the most from the material i sent it out to get heat treated for maximum "toughness". What i got was maximum hardness.

 

[metengr]

You might want to re-review this thread, since you asked the original question;

thread330-173553

 

[marmon]

yes, i relaize that. That question was for material choice, i have since chose 4150 as stated above. Now i need to know at what level maximum toughness is acheived at which i cant find from the suppliers. i also want to know that since the parts were heat treated wrong, can they be brought back down without sacrifice. a completely different topic really

 

[metengr]

If you need the toughness, I would temper at 1100 deg F for 1 hour. According to my sources, for 4150 this tempering temperature would result in about a 40 HRc hardness with excellent toughness.

 

[arunmrao]

You can definitely undo what has been done i.e lowering the hardness. Only watch out for scaling and distortion related problems. A high temperature 600C should considerably drop your hardness and improve the toughness of your component.

 

[EdDanzer]

Are you sure it is 4150 or is it ETD150? There is a difference in these materials if you do additional heat treating.
It would be good to know what the other pins we made of their hardness and what the failure was.
You will have distortion and some scaling after drawing these parts back. It may be better to centerless grind the parts after heat treating.

 

[marmon]

i am positive it is 4150,
The heat treat company is arguing that there testing shows a Rc of 48-52, while my measurements show 60+. Of course i can not get a copy of their test results.
I can honestly say that where i'm from it is extremely difficult to pick materials for various projects. There seams to be nobody locally to consult with, about material choice and properties. Any supplier also seems to be clueless on material properties and characteristics. Liabilty? I don't know but in the business i'm in it could be extremely helpful to at least be able to offer a customer a choice or an alternative material for a better product. Thanks for the help, i will try to get these parts annealed, hopefully all costs covered.

metengr: you mention your sources, do you have any references you reccommend? I would like to have better understanding on many of the readily available materials.

 

[dbooker630]

I'm not sure of your section size, but it may be a good idea to check the core hardness on the parts as-is.

Depending on size, quenchant used/severity, the 60HRC hardness you mention may not extend very deep into the part.

If the heat treater got 48-52 on their check either their hardness testers are way out of cal or they burned the sample trying to create a flat spot for testing. With that much discrepancy I would question the entire heat treat and inspection practice.

 

[TVP]

marmon,

ASM International offers a number of different publications that would be useful to you in material selection. Specifically on the heat treatment of steels, ASM HANDBOOK Volume 4 Heat Treating and Heat Treater's Guide: Practices and Procedures for Irons and Steels, 2nd Edition will have information on how to heat treat steels and what the resulting properties will be. Use the following link for more information:

http://www.asminternational.org/Tem...=Ecommerce/ProductDisplay.cfm&ProductID=10852

 

[NickE]

Are you testing on the round? Is the heat treater? Did everyone read the chart correctly?

As dbooker630 said, sample prep could be the issue. If they wont give you the results of their internal inspection then dont accept the parts. (Some days I wish I didnt have to provide the results of some of my inspections. Hah!) Have a decent size sample from the whole batch tested at an outside A2LA Lab. Nobody wants to reject good product. Get the treater to split the cost. This wont be too expensive.

To determine the existance of a hardness profile use Vickers Micro, have a through section mounted and a profile taken. Again not that expensive and good insurance.