×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

hardness values

hardness values

hardness values

(OP)
Can anyone advise me on the ideal and expected surface and core hardnesses for bearing quality balls of 64mm diameter made from 100Cr6 and 100CrMn6 ?

Am I right in believing that the 100CrMn6 would give a more uniform hardness and therefore less internal residual stress ?

RE: hardness values

At mid range of the analysis for these two alloys the ideal diameter is about 85-mm for 100Cr6 and about 230-mm for 100CrMn6 resulting from higher silicon and manganese.
For a 64-mm ball therefore I would expect to see approximately the same hardness profile for both alloys which would be essentially flat at around 62 - 63 Rc.

RE: hardness values

(OP)
Thanks both for your good info.

Carburise, what do you mean by 'ideal diameter'. Previously someone said the the maximum thickness for full through-hardening in 100Cr6 was 32mm. This seems along way from the dimensions you give of 85 and 230mm so these things may not be connected. Perhaps you can explain to me a little more please ?

RE: hardness values

The "ideal diameter" is a term developed by Grossman in the late 30's to describe the hardenability of an alloy and represents the diameter of an infinitely long bar which will quench to 50% martensite in the center.

RE: hardness values

(OP)
So at a diameter of 32mm, you would get perhaps 100% martensite at the core ? So at with 64mm and spherical, we would be closer to 100% than 50% martensite ?

I guess the remaining material is mainly austenite and the difference in structure gives rise to potential residual stresses ?

RE: hardness values

Correct concerning the sphere.
The non martensitic product will most likely be bainite rather than austenite.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources