Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials

Strain controlled constant and variable amplitude fatigue tests for 316NG and Titanium stabilized stainless steels in low oxygen PWR waters were performed. The stabilized steel has been plant aged for 100 000 hours. Constant amplitude test results at 0,01 Hz sinusoidal straining comply with predicted lives according to the Fen approach for both materials. Spectrum straining both in air and in environment caused predicted life reduction factors (about 3) for the stabilized steel, but for the 316NG steel spectrum straining in environment resulted to a larger reduction in life.

Download Full-text

Effects of Actual Marine Atmospheric Pre-Corrosion and Pre-Fatigue on the Fatigue Property of 7085 Aluminum Alloy

Metals ◽

10.3390/met12010081 ◽

2022 ◽

Vol 12 (1) ◽

pp. 81

Author(s):

Laixin Shi ◽

Lin Xiang ◽

Jianquan Tao ◽

Jun Liu ◽

Qiang Chen ◽

...

Keyword(s):

Aluminum Alloy ◽

Fatigue Life ◽

Pitting Corrosion ◽

Atmospheric Corrosion ◽

Fatigue Property ◽

Outdoor Exposure ◽

Fatigue Tests ◽

Constant Amplitude ◽

Fatigue Fractography ◽

Corrosion Mode

Effects of actual marine atmospheric precorrosion and prefatigue on the fatigue property of 7085-T7452 aluminum alloy were investigated by using the methods of marine atmospheric outdoor exposure tests and constant amplitude axial fatigue tests. Marine atmospheric corrosion morphologies, fatigue life, and fatigue fractography were analyzed. After three months of outdoor exposure, both pitting corrosion and intergranular corrosion (IGC) occurred, while the latter was the dominant marine atmospheric corrosion mode. Marine atmospheric precorrosion could result in a dramatical decrease in the fatigue life of the as-received 7085-T7452 aluminum alloy, while selective prefatigue can improve the total fatigue life of the precorroded specimen. The mechanism of the actual marine atmospheric corrosion and its effects on the fatigue life of the 7085-T7452 aluminum alloy were also discussed.

Download Full-text

The Effects of Periodic High Loads on Fretting Fatigue

Journal of Engineering Materials and Technology ◽

10.1115/1.3225005 ◽

1981 ◽

Vol 103 (3) ◽

pp. 223-228 ◽

Cited By ~ 2

Author(s):

A. Kantimathi ◽

J. A. Alic

Keyword(s):

Aluminum Alloy ◽

Fatigue Life ◽

Growth Retardation ◽

Fretting Fatigue ◽

Fatigue Tests ◽

Constant Amplitude ◽

Axial Loads ◽

Prolonged Fatigue ◽

Stress Ratios ◽

Crack Growth Retardation

Fretting fatigue tests have been conducted on 7075-T7351 aluminum alloy coupons with fretting pads of the same material. Three different stress ratios were used, the otherwise constant amplitude axial loads being interrupted every 1000 cycles by either tensile overloads to 400 MPa or compressive underloads to −200 MPa. Tensile overloads greatly prolonged fatigue life for low stresses where the overload ratios were 1.6 and above; compressive underloads had comparatively little effect. The results are discussed in terms of crack growth retardation phenomena.

Download Full-text

Energy Accumulation in Steel, in the Conditions of Constant-Amplitude

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.240.114 ◽

2015 ◽

Vol 240 ◽

pp. 114-121

Author(s):

Stanisław Mroziński ◽

Michał Piotrowski

Keyword(s):

Crack Initiation ◽

Strain Energy ◽

Fatigue Tests ◽

Constant Amplitude ◽

P91 Steel ◽

Energy Accumulation ◽

Different Order ◽

Different Levels

This work presents results of fatigue tests of P91 steel specimens under constant-amplitude and programmed loading in temperature T=600°C. Two strain levels, applied in different order, were used for programmed loading. The loading program level changes were introduced for different levels of damage. The tests provided the basis for analysis of strain energy ΔWpl in the function of the number of load cycles under constant-amplitude and programmed loading. It has been found that that the form of a loading program has an influence on the life and value of energy cumulated in the specimen until crack initiation. Verification of Palmgren Miner hypothesis revealed that its effectiveness depends on the loading program and temperature.

Download Full-text