Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Fatigue strength of 304, cold worked versus annealed

  1. Dec 3, 2009 #1

    Q_Goest

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    This web page: http://www.hghouston.com/ss_cwp.html [Broken]

    states:
    The web page also shows that fatigue strength can be improved dramatically by cold working. Endurance limit is listed as:
    304 annealed = 35 ksi
    304 3/4 hard = 92 ksi

    I'm in the process of designing something that will be subject to fatigue. Cycles will quickly exceed 10^6 cycles, and even 10^8 cycles will come along all to quickly. The part is in axial tension/compression. It will have stress concentrations of about 2 or 3. But the statement makes me wonder...

    Which material would be best, annealed or cold worked? How can this be quantified?
     
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Dec 7, 2009 #2

    Astronuc

    User Avatar

    Staff: Mentor

    I'm wondering under what conditions the quoted statement is made. CW metal has a greater elastic range than annealed metal, and obviously higher yield strength.

    On the other hand, the uniform elongation of annealed material is much greater, so strain to failure is greater. Annealed materials are more creep resistant than CW material, and perhaps the quote is referring to creep related cracking at the tip of a notch.
    http://www.hghouston.com/services_9.html [Broken]

    My question would be - what are the expected stresses as compared to yield strength of ANN and CW steels.
     
    Last edited by a moderator: May 4, 2017
  4. Dec 8, 2009 #3

    Q_Goest

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Hi Astronuc,
    That's difficult to determine because there is no really good information on stress concentration factors for threaded parts. This particular part has a 1.750-8 thread and seems to be failing regularly due to fatigue, generally after about one million cycles. The crack initiates at a thread root.

    I'm trying to determine if a cold worked version of the material will improve that or not.
     
  5. Dec 8, 2009 #4

    Astronuc

    User Avatar

    Staff: Mentor

    I have an ASTM STP about fracture of threaded fasteners. Let me see if I can find it.
     
  6. Dec 8, 2009 #5

    Q_Goest

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Thanks. If you have the spec number I should be able to get it.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Fatigue strength of 304, cold worked versus annealed
  1. Annealed Brass (Replies: 2)

Loading...