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!

*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

ASTM E10 section 7.6.4 varbiage

ASTM E10 section 7.6.4 varbiage

ASTM E10 section 7.6.4 varbiage


I am trying to create a verification formula based on ASTM E10 section 7.6.4:
"When indentations are made on a curved surface, the
minimum radius of curvature1 of the surface shall be two and a
half times the diameter of the ball
2. Indentations made on
curved surfaces may be slightly elliptical rather than circular in
shape. The measurements of the indentation shall be taken as
the mean of the major and minor axes."

So here's the issue

2a = minor axis = d0
2b = major axis = d90
=> Rmin=d902/2d0


"Shall be" implies equals to. I was expecting some sort of greater than or less than situation. it seems this scenario is highly unlikely!


So unless I'm not thinking through this correctly.. in a case where a 10mm ball is used, the only scenario where this equation is satisfied is when the ratio of d902/d0 comes out to exactly 50mm. for example d90= 10mm and d0=2mm.

This seems like a very strict requirement...

Replies continue below

Recommended for you

RE: ASTM E10 section 7.6.4 varbiage

What is wrong with the word "minimum"?
That means that "shall be" is the minimum, doesn't it?

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: ASTM E10 section 7.6.4 varbiage

No. The word minimum is referring to the minimum radius of curvature, which is the calculated value Rmin. The sentence would need to be structured as "the minimum radius of curvature of the surface shall be at a minimum two and a half times the diameter of the ball" to make sense.

Unless, again, I'm not looking at this correctly.

RE: ASTM E10 section 7.6.4 varbiage

Rmin = 2.5D sure seems like a minimum to me.

RE: ASTM E10 section 7.6.4 varbiage

R=b^2/a is for curvature of an ellipse. The min radius of curvature in ASTM refers to the surface of test piece. for example, flat surface has an infinite radius, the ideal situation to calculate the BHN numbers since the indentation will be symmetric if the material is isotropic.

if the radius of curvature is too small, the test surface is very non-smooth, the diameter of indentation will be too small, yielding a higher BHN than would-be for a convex surface.

in addition, avoid testing a concave surface (if not flat). No idea if ASTM specifies to use a convex surface.

RE: ASTM E10 section 7.6.4 varbiage

Thanks! that makes sense.

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! Already a Member? Login


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close