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


steel strength

steel strength

steel strength

Hi guys
Is it possible a steel to withstand 1600MPa in bending, because i'm a witness of that by applying 260Nm (90kg x 0.3m)bending moment of a shaft Ø12,
It withstood it even without crook.
According to the formula σ = (32.M)/(π.D^3) = 1532MPa
Is that true or I'm wrong in the calculation.
Thanks in advance for your opinion

RE: steel strength

Check your units, yes the equation is correct if both ends are free.
If one end is fixed (in a collar or similar) then you have to change things a bit.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: steel strength

I applied a cantilever load. I pushed one side in a hole and step 30cm away from the hole with my body weight (90kg). Bending moment = 882.9N x 0.3m = 264.87Nm
(264.87Nm x 32)/(π x 1.2cm ^3)= 1561MPa. If add the shear and contact stress it must've exceed 1600MPa
I did that experiment in order to check the hardened steel strength myself as the information I found differs too much.
But if my result is correct why there is no such amount of strength in any of the steel properties lists.
But I prefer to believe rather on my eyes then the lists
Am I going to make a revolution in the engineering science?lol

RE: steel strength

Greg, 1500MPa is about 200ksi.

Did the end deflect about 40mm?
Are you sure that there was no permanent deformation?

I am sorry but unless this is some very special grade of steel I cannot imagine a 1/2" bar, 12" long, taking a 200lb end load without some set.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: steel strength

I'm absolutely sure in the values, I did it twice, there was no deformation at all. It's an ordinary hardened shaft, I don't know from what machine,I have plenty of scrap like that at home.
Today I tried with another metals and the results was also amazing.
-Drive shaft from a car Φ22 in bending 1600Mpa (my weight 90kg at 1.8m + weight of the lever)and probably more as I did not dare to broke it, because it can injure me

at the same way I obtained
-piece of concrete rebar Φ14, in bending - 1400MPa starts to deform.
-Threaded dowel (plain carbon steel) M14 in bending 800Mpa starts to deform
-Threaded dowel M8 (Φ6 inner) in tensile about 800Mpa tears (23000N force - my weight through a lever)
So I feel a bit confused, considering the difference with values of strength I've known

Who don't believe can try, it's pretty simple

RE: steel strength

The shafts could be case hardened. And given that the highest stress in on the surface that case would be helping support the load, even if the core strength is lower.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: steel strength

Next time I thing to test a shaft in torsion if find where to spline it.
Shafts OK but what about the low carbon steel shouldn't its ultimate strength be about 350Mpa(51ksi) not 800MPa (116ksi)

RE: steel strength


Automotive shafts for driveline and transmission applications are either surface hardened by induction heat treatment, or by case carburizing. Typical surface hardness is 59 HRC minimum, which means that a surface bending stress under maximum load should be less than ~ 2200 MPa. The strength of the part varies from the surface to the core depending on the steel grade and the details of the heat treatment.

RE: steel strength

TVP,You probably mean it shouldn't be less than ~ 2200 MPa
And in conclusion I accept it's normal automotive shafts to withstand 1500+ Mpa.
But I wonder what is the predetermined stress in the design of high strength auto parts like drive shafts ets

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