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Bethlehem Hot-Rolled XF Sheet Steels
Fatigue Properties
A structural member subject to cyclic stress can fail at a load whose maximum
amplitude is considerably smaller than the load required to produce static failure. It is
this property of structural materials that is so troublesome to designers of structures
and components (e.g., wheels) which are subject to cyclic loads and vibrations.
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| To provide the designer with necessary design data, cyclic strain-life
curves (Figure 9) and cyclic stressstrain curves (Figure 10) are illustrated for
B50XF and B80XF. To further assist designers, the table below summarizes the monotonic and
cyclic parameters for these two grades. The tests to develop these data were conducted
according to ASTM E 60680. The cyclic strain-life and stress-strain parameters can
be used to estimate fatigue performance for various notched conditions using the
local-strain or Neuber life assessment model. |
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Typical Parameters for Fatigue Design
| Grades |
B50XF |
B80xf |
| Thickness, inch (mm) |
0.107 (272) |
0.082 (2.08) |
| Monotonic |
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Yield strength, Sy, ksi, (MPa)1
Tensile strength, Su, ksi (MPa)1 |
58.1 (401)
70.5 |
82.6 (570)
93.5 (645) |
| Cyclic |
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Yield strength, Sy1, ksi, (MPa)1
Strain-hardening exponent, n'
Strength coefficient, k', ksi (MPa)
Fatigue strength coefficient, o'f, ksi (MPa)
Fatigue strength exponent, b
Fatigue ductility coefficient, e'f
Fatigue ductility exponent, c |
49.9 (344
0.113
101.0 (697)
163.0 (1124)
-0.113
1.38
-0.682 |
75.7 (522)
0.0817
126.0 (869)
222.0 (1531)
-0.110
3.14
-0.852 |
10.2% offset yield strength
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�1999, Bethlehem Steel Corporation |