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Influence of machining parameters on fatigue endurance limit of AISI 4140 steel Article (PDF Available) in Journal of the Brazilian Society of Mechanical Sciences and Engineering 30(1) · March
Apr 27, 2006 · RE4130 Endurance Limit. 27 Apr 06 14:52. There are factors beyond what some formulas may tell you. The question was based on what truck axle manufacturers and race axle companies use; 4340 (which includes 300m), 1550 and "Hy-Tuf".
Fatigue tests were carried out on 4140 steel heat treated to various hardness levels. Environmental effects are reported in dry and moist air, aerated and deaerated 3 pet NaCl solution, and under conditions of cathodic protection and of passivity. Critical corrosion rates were measured below which the environment does not affect fatigue life.
•No True endurance limit (Fatigue strength at N=5x108 often used) S n‘ = 0.4 x S u (for S u < 48 ksi) (like for cast iron) Fatigue strength at N=5x108 Tensile Strenght Su (ksi) Su (MPa) Life N (cycles) Endurance Limit S-N curve approximation Endurance limit Steel S n‘ = 0.5 x S u Cast Iron Aluminum
4140 hardened and tempered bar can also be successfully nitrided, giving a surface hardness of up to Rc 60. Nitriding is carried out at 490 oC - 530 C, followed by slow cooling (no quench) reducing the problem of distortion. Parts can therefore be machined to near final size, leaving a grinding allowance only.
Figure 6Residual macrostresses vatiation in 4130 steel with fatigue cycling at numerous depthsat the surface (solid circles), near the surface (at depth, d=0.001 in.) at the stress profile minimum (d=0.007 in.), at the cross-over point (d=0.013 in.).
A statistical evaluation of fatigue test data is given in Table 3, in which the extreme values of endurance limit satisfying 95% confidence limit are given together with the average values for all conditions of heat treatments. Download Download full-size image; Fig. 7. Fatigue curves of heat treated, liquid and ion nitrided AISI 4140 steel for various process times.
106-cycle strength (endurance limit) S n’ Moore endurance limit 1000-cycle strength Bending Axial Torsion C L (load factor) 0.9S u 0.75S u 0.9S us steelS us=0.8S u other ductile metalsS us=0.7S u Bending Axial Torsion C L (load factor) 1 1 0.58 C G (gradient factor) < 0.4” 1 0.70.9 1 0.4”2” 0.9 0.70.9 0.9 2”4” r e d u c e - 0.1
4140 HIGH TENSILE STEEL 4140 is a 1% chromium - molybdenum medium hardenability general purpose high tensile steel - generally supplied hardened and tempered in the tensile range of 850 - 1000 Mpa (condition T).4140 is now available with improved
properties of this grade greatly deteriorate when hardened to higher strength. At comparable strength levels the minimum toughness of Atlas 4140 is about three times higher than that of Atlas 1045. This means that Atlas 4140 can absorb three times the impact needed to fracture Atlas 1045.
The fatigue limit of AISI 4140 steel increases almost 18% with increasing depth of cut from 0.4 to 1.2 mm. Further increase in depth of cut to 2.0 mm has no pronounced influence on the average fatigue limit of this steel. However, the dispersion of the fatigue limit increases with increasing depth of cut.
Sep 11, 2019 · Endurance limit (Se) is the stress level below which a specimen can withstand cyclic stress indefinitely without exhibiting fatigue failure. Rigid, elastic, low damping materials such as thermosetting plastics and some crystalline thermoplastics do not exhibit an endurance limit. On the other hand, steel exhibits a high endurance limit.
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