Fatigue Strength Of Carbon Steel Research Articles

The Effect of Tensile and Compressive Deformations on Fatigue Strength of Carbon Steel

The phenomenon of fatigue strength being increased by preliminary working has often been the subject of studies, and the increase of fatigue strength due to plastic deformation is thought to be a consequence of residual stress and micro structural change caused by plastic deformation, so that the fundamental relation between fatigue strength and residual stress or micro structural change is to be studied.In this paper, the effect of preliminary working on the fatigue strength of S45C steel is studied from the influences of residual stress and micro structural change caused by tensile and compressive deformations. As the result of the study, it is found that micro structural change is considered to be more responsible than residual stress for the increase of fatigue strength.

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

It is well known that the fatigue strength of machine part is generally reduced when plated with Chromium. But for nickel plating of steel there have yet been but scanty data for ensuring the effective fatigue strength. The author has investigated on that account the effect of nickel plating on the fatigue strength of carbon steel.The fatigue test specimens used in the present experiment were 10mm in diameter, and were made of annealed 0.15%C steel or annealed and quenched-tempered 0.45%C steel. The nickel plating of these fatigue test specimens was carried out in the Watt's type bath, having the composition NiSO4·7H2O 240g/l, NiCl2·6H2O 45g/l, H3BO3·30g/l. Then the current densities were 1.0, 0.7, 0.5A/dm2, and the bath temperature was kept at 25°C.The results obtained can be summarized as follows.1) The higher the fatigue limit is in unplated steel the lower the limit is in nickel plate steel, no matter what the plating condition is.2) The higher the plating current density is the larger the drop of the fatigue limit in nickel plated steel is. It is considered that this is closely connected with the presence of residual tensile stress in the plated layer.3) Moreover, the drop of the fatigue limits in the nickel plated steel is influenced by the plate thickness. The increase of the plate thickness lowers the fatigue limit. This is probably the notch effect due to the rough plate surface and to the crack in the plated metal.

Effect of liquid low-melting metals on the fatigue strength of carbon steel in relation to the stress frequency

It was established that the increase in the endurance of steel under the influence of molten metals is larger in the case of specimens with stress raisers. On the other hand, increasing the stress frequency produces a reduction in the endurance of steel in molten metals.

Effect of calorizing on the fatigue and corrosion-fatigue strength of steel 45

1. Calorizing to a depth of 0.1–0.2 mm produces a sharp reduction in the fatigue strength of carbon steel but has practically no effect on its corrosion-fatigue strength. 2. Calorizing to a depth of 0.04–0.05 mm produces a slight reduction in the fatigue strength of steel in air and more than doubles its conventional corrosion-fatigue limit.

An experimental study on the fatigue strength of carbon steels

An experimental study on the fatigue strength of carbon steels

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

The Influence of Non-metallic Inclusions on the Fatigue Strength and the Statistical Nature of Steel

Three series of specimens were specially prepared so that they may contain various degrees of MnS non-metallic inclusions, other parameters being kept constant especially the amount of manganese in solution as much as possible. Fatigue tests were carried out with a rotating bending fatigue machine.The results obtained are as follows:(1) The definite relationship could not be recognized between the inclusion ratings and the statistical nature of fatigue life of steel, which is in accordance with the previous work by one of the present authors, but contrary to the result by Epremian and Mehl.(2) The ferrite grain size is a predominant metallurgical factor in the statistical nature of fatigue fructure of steel.(3) For the same stress amplitude, the scatter of fatigue life increases and the probability of fructure decreases with the decrease of grain size.(4) For the equivalent stress amplitude, the scatter of fatigue life appears not to be affected by inclusion ratings and ferrite grain size.(5) The longitudinal fatigue strength of carbon steel is not so much affected by the content of MnS as inclusions. The effect by ferrite grain size or other statistical parameters may also be large.

A Study on the Fatigue Strength of Carbon Steels under Multiple Repeated Stresses

In this paper, we tried to predict the fatigue strength of carbon steels which are subjected to multiple repeated stresses from the results of ordinary fatigue tests. The new relation is based on the already reported equation derived from the assumption that fatigue is caused by the accumulation of the distortion of atom lattice. We considered the effects of the access ratio of stresses, cycle ratio and carbon content of materials, from several experimental data. On the basis of this consideration, we derived an equation expressing the relation between the rotary bending stresses and the number of stress repetitions under multiple repeated stresses on two stress levels. The values calculated by the equation have been found in good agreement with those obtained from the experiment.

The Effect of Atmosphere on Fatigue Strength of Carbon Steels at Elevated Temperature

Fatigue tests of carbon steels were carried out at 550°C under rotating bending and also under repeated torsion in town gas to reduce air oxidation, as a first step to study effects of atmosphere on fatigue strengths at elevated temperatures. For long lives under low stresses, the strength was higher in gas than in air, and the influence of corrosion fatigue due to oxidation was found in air at high temperature. While the strength was lower in gas than in air for short lives under high stresses, and S-N curves in air and in gas cross each other. This may be attributed to hydrogen embrittlement resulting from the decomposition of water vapor. The S-N curve at elevated temperatures may take considerably different shape by removing effects of oxidation by air, and its slope becomes more gentle after long time.

The effect of liquid lead-tin eutectic on the fatigue strength of carbon steel

The effect of liquid lead-tin eutectic on the fatigue strength of carbon steel

A Study on the Fatigue Strength of Carbon Steels under Multiple Repeated Stresses

A Study on the Fatigue Strength of Carbon Steels under Multiple Repeated Stresses

Effects of Cycle Frequency on the Corrosion Fatigue Strength

The effects of cycle frequency on the fatigue strength of carbon steels under simultaneous corrosion in city water or saline are studied. The stress σc given under corrosion fatigue increases to σck owing to the notch effect of corrosion pits. At a certain repetition number of N, σck reaches the fatigue strength σ of same repetition number in air and fractures by corrosion fatigue occur. As σ is a function of N alone, and k depends mainly on time t, the condition of fracture may be expressed as σck(t)=σ(N). Various experimental results are well explained by this criterion. This conception is further extended to the corrosion fatigue combining the static pre-corrosion and also changing cycle frequencies during run.

Effects of Cycle Frequency on the Corrosion Fatigue Strength

The effects of cycle frequency on the fatigue strength of carbon steels under simultaneous corrosion in tap water and saline are studied. The stress σc given under corrosion fatigue increases to σck owing to the notch effect of corrosion pits. At a certain repetition number of N, σck reaches the fatigue strength σ of the same repetition number in air and fractures by corrosion fatigue occur. And the condition of fracture is given by Eq. (5), under consideration that the corrosion effect k increases with time and σ is a function of N alone. Various experimental results are well explained by this criterion. This conception is further extended to the corrosion fatigue combining the static pre-corrosion and also changing cycle frequencies during runs. For the corrosion fatigue under varying stress amplitudes the cumulative damage criterion was found to be applicable. And so the strengths of corrosion fatigue under wide stress conditions may be known.

鋼の疲労における時効の効果

The mechanical properties, especially the fatigue strength of carbon steel are improved by the low-temperature quenching and the spheroidizing treatments, because of the diffusion of carbon and nitrogen atoms occurring in such a ferrite structure.In the present paper, the investigation has been done to understand the effects of quench aging and that of strain aging on the fatigue strength of 0.04% and 0.59% carbon steels which were quenched at low temperature and spheroidized at 700°C. When the specimens were aged at 100°C, their hardness increased with aging time, and reached the maximum at about 40min, regardless of their carbon contents and structures. In this case the maximum difference of hardness, named “Age-hardening-power”, would be a measure of the ability of age-hardening of the material.In the material with high age-hardening-power, the strength at the notch root region will be increased during repeated loading. This is explained from the fact that a fairly good agreement between the hardness distribution and the stress distribution on the section across the notch root is obtained in the spheroidized specimen with a high age-hardening-power, while the hardness of annealed steel remains unchanged.The region resisting against the fatigue failure of notched specimen develops inward more and more during repeated loading in the structure which has high age-hardening-power, therefore the resistance to fatigue failure is raised. In the other hand, the fatigue notch coefficient β must be decreased with increasing age-hardening-power, ΔHmax, and the result obtained would be represented by the following equation for the stress concentration factor α=3.3, β=k1e-k2ΔHmax where k1 and k2 are constants depending on materials.From the above, it may be concluded that if a material is capable of strain-aging, it has good fatigue strength, because in such a material, dislocation movements are impeded both by fine precipitates and by solute atoms anchored to them.

材料の疲れ強さ整理資料の解説(疲れおよびクリープ特集)

材料の疲れ強さ整理資料の解説(疲れおよびクリープ特集)