On the low-cycle fatigue behavior of thermo-mechanically processed high-strength aluminum alloys

Low-cycle fatigue (LCF) life and failure mechanism of 7075-T6 high strength aluminum alloys were investigated under MTS 809. The cycling stress response and the cyclic stress—strain relationships under different strain amplitudes were investigated. Using Manson-Coffin law, the three parameter exponential function equation and the damage function model of tensile hysteresis energy (Ostergren equation), the regression analysis of LCF test data was carried out, it was found that the fatigue life prediction results of the three parameter exponential function equation were better than the other two life prediction methods in terms of statistical analysis methods of standard deviation and dispersion band. Analysis of microstructure and fatigue failure fracture revealed that fatigue crack initiated at the interface of precipitations and α-phase aluminium substrate in surface or near surface of the sample.

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On the Low Cycle Fatigue Behavior in the Longitudinally Butt Welded Joints between High Strength Steel and Mild Steel

Journal of the Society of Naval Architects of Japan ◽

10.2534/jjasnaoe1968.1977.142_236 ◽

1977 ◽

Vol 1977 (142) ◽

pp. 236-244

Author(s):

Kinichi Nagai ◽

Mitsumasa Iwata ◽

Kenhichiro Kurihara ◽

Junkichi Yagi ◽

Yasumitsu Tomita

Keyword(s):

Mild Steel ◽

Welded Joints ◽

High Strength Steel ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

High Strength ◽

Cycle Fatigue

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Fretting Fatigue Behavior of High Strength Aluminum Alloys

Transactions of the Korean Society of Mechanical Engineers A ◽

10.3795/ksme-a.2007.31.2.197 ◽

2007 ◽

Vol 31 (2) ◽

pp. 197-204

Author(s):

Sung-Jong Choi ◽

Hak-Sun Lee ◽

Cheol-Jae Lee ◽

Sang-Tae Kim

Keyword(s):

Aluminum Alloys ◽

Fatigue Behavior ◽

High Strength ◽

Fretting Fatigue ◽

High Strength Aluminum Alloys

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Low Cycle Fatigue Characteristics of a Low-Thermal Expansion, High Strength Alloy (HAYNES 242 Alloy)

Volume 4: Cycle Innovations; Fans and Blowers; Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Oil and Gas Applications ◽

10.1115/gt2011-46817 ◽

2011 ◽

Author(s):

L. M. Pike ◽

S. K. Srivastava

Keyword(s):

Thermal Expansion ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Strain Range ◽

High Strength ◽

Wave Form ◽

Cycle Fatigue ◽

Total Strain Range ◽

Low Thermal Expansion ◽

Long Range Ordering

HAYNES® 242® alloy, based primarily on the Ni-25Mo-8Cr system, derives its low thermal expansion characteristics from its composition and its high strength concomitant with high ductility from a long-range ordering reaction upon an aging heat treatment. This combination has enabled the alloy continually to find a challenging range of applications in the aerospace industry at up to 1300°F (704°C). These include seal rings, containment rings, duct segments, casings, rocket nozzles, etc. In conjunction with the creep strength and environmental resistance, the low cycle fatigue (LCF) behavior is an important material property affecting the service life of 242 alloy components. The low cycle fatigue behavior of 242 alloy was studied under fully reversed strain-controlled mode at 800°F (427°C), 1000°F (538°C), 1200°F (649°C) and 1400°F (760°C) using a triangular wave form with a frequency of 0.33 Hz. Results are presented in terms of cycles to crack initiation and failure. The magnitudes of fatigue lives at total strain range ≤ 0.7% at 800, 1000 and 1200°F are significantly greater than those of solid solution strengthened alloys. Additionally, stress-controlled LCF tests were performed at 1200°F (649°C) on 242 alloy as well as 909 alloy (for comparison). The paper will discuss the results of these two test programs.

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Comparative Low-Cycle Fatigue Behavior of HAYNES 244 Alloy and Waspaloy

10.1115/gt2021-59619 ◽

2021 ◽

Author(s):

Michael G. Fahrmann

Keyword(s):

Thermal Loading ◽

Coefficient Of Thermal Expansion ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Axial Strain ◽

Fatigue Crack Initiation ◽

High Strength ◽

Cyclic Hardening ◽

Cycle Fatigue ◽

Softening Behavior

Abstract HAYNES® 244® alloy was chiefly developed to address the need for high-strength, low coefficient of thermal expansion (CTE) alloys for seal rings and cases in advanced gas turbine engines. In addition to these attributes, adequate resistance to low-cycle fatigue (LCF) due to cyclic thermal and mechanical loading during service is critical for such applications. The isothermal LCF performance of commercially produced 0.5” (12.5 mm) thick, fully heat treated plate products of 244 alloy was evaluated by means of axial strain-controlled (R = −1) LCF tests covering total strain ranges up to 1.25 % (without dwells), at temperatures ranging from 800–1400°F (427–760°C). In addition, the comparative LCF performance of Waspaloy, a well-established alloy for turbine cases, was evaluated under selected, nominally identical test conditions. S-N curves were constructed and fitted by the Coffin-Manson equation, allowing the delineation of regimes controlled by the elastic and plastic response of the material. Fracture surfaces were examined in the scanning electron microscope to identify fatigue crack initiation sites and crack propagation modes. Differences between the alloys are discussed in terms of tensile strength and cyclic hardening/softening behavior. Implications for fatigue performance of these alloys under cyclic thermal loading conditions are discussed as well.

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