steel - Nouvelle page 1 - Free
steel - Nouvelle page 1 - Free
steel - Nouvelle page 1 - Free
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MMPDS-01<br />
31 January 2003<br />
Figure 2.3.1.3.8(a). Best-fit S/N curves for unnotched AISI 4340 alloy <strong>steel</strong> bar, F tu =<br />
125 ksi, longitudinal direction.<br />
Correlative Information for Figure 2.3.1.3.8(a)<br />
Product Form: Rolled bar, 1.125 inch diameter,<br />
air melted<br />
Properties:<br />
TUS, ksi TYS, ksi Temp., EF<br />
125 — RT<br />
(unnotched)<br />
150 — RT<br />
(notched)<br />
Specimen Details: Unnotched<br />
0.400 inch diameter<br />
Surface Condition: Hand polished to RMS 10<br />
Reference:<br />
2.3.1.3.8(a)<br />
Test Parameters:<br />
Loading - Axial<br />
Frequency - 2000 to 2500 cpm<br />
Temperature - RT<br />
Atmosphere - Air<br />
No. of Heat/Lots: 1<br />
Equivalent Stress Equation:<br />
Log N f = 14.96-6.46 log (S eq -60)<br />
S eq = S max (1-R) 0.70<br />
Std. Error of Estimate, Log (Life) = 0.35<br />
Standard Deviation, Log (Life) = 0.77<br />
R 2 = 75%<br />
Sample Size = 9<br />
[Caution: The equivalent stress model may<br />
provide unrealistic life predictions for<br />
stress ratios beyond those represented above.]<br />
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