Mean stress models for low-cycle fatigue of a nickel-base superalloy

Fang, Daining; Berkovits, A.

doi:10.1016/0142-1123(94)90458-8

Cited by 41 publications

(23 citation statements)

References 4 publications

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“…Influence of the mean stress ( σ m ) on TMF lifetime cannot be ignored . Figure C depicts the influence of mechanical strain amplitude on the cyclic mean stress of 4Cr5MoSiV1 steel during IP and OP TMF cycling.…”

Section: Resultsmentioning

confidence: 99%

“…Influence of the mean stress (σ m ) on TMF lifetime cannot be ignored. 22,23 Figure 9C depicts the influence of mechanical strain amplitude on the cyclic mean stress of 4Cr5MoSiV1 steel during IP and OP TMF cycling. The phenomenon of σ m , which is formed during TMF tests, results first from the yield strength dependence of the temperature and second from the phase relation between the temperature and mechanical strain.…”

Section: Cyclic Stress and Strain Response Behaviormentioning

confidence: 99%

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In‐phase and out‐of‐phase thermomechanical fatigue behavior of 4Cr5MoSiV1 hot work die steel cycling from 400 °C to 700 °C

Pengpeng

Zeng

et al. 2017

Fatigue Fract Eng Mat Struct

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The hysteresis loops, stress and strain behavior, lifetime behavior and fracture characteristic of 4Cr5MoSiV1 hot work die steel at a wide range of mechanical strain amplitudes (from 0.5% to 1.3%) during the in-phase (IP) and out-of-phase (OP) thermomechanical fatigue (TMF) tests cycling from 400°C to 700°C under full reverse strain-controlled condition were investigated. Stress-mechanical strain hysteresis loops of 4Cr5MoSiV1 steel are asymmetric, and stress reduction appears at high-temperature half cycles owing to a decrease in strength with increasing temperature. 4Cr5MoSiV1 steel always exhibits continuous cyclic softening for both types of TMF tests, and the cyclic softening rate is larger in OP loading condition. OP TMF life of 4Cr5MoSiV1 steel is approximately 60% of IP TMF life at the same mechanical strain amplitude and maximum temperature. Lifetime determined and predicted in both types of TMF tests is adequately described by the Ostergren model. Fracture surfaces under IP TMF loading display the striation and tear ridge, showing quasi-cleavage characteristics, and the cracks are less but longer. However, fracture surfaces under OP TMF loading mainly display the striation and dimple characteristics, and the cracks are more and shorter. KEYWORDS cyclic softening, cyclic stress-strain behavior, fatigue life, hot work die steel, thermomechanical fatigue | INTRODUCTIONDuring the die filling process, like die casting, hot extrusion, hot forging or hot stamping, the service life of hot work die is limited because of their extreme working environments in terms of the cyclic alternating high temperature, which results from the close contact between hot work die and hot work piece (1200°C for steel forging) or molten metal (675°C for Al-alloy casting, 930°C for Cu-alloy casting) and mechanical stress, leading to cyclic plastic deformation, which gives rise to crack initiation. [1][2][3][4] All along, the hot work die is damaged through a complex oxidation/wear/non-isothermal low cycle fatigue interaction. 5,6 Therefore, non-isothermal low cycle fatigue damage (occurrence of the cyclic reversed plasticity at low and high temperatures) of hot work die is usually called thermomechanical fatigue (TMF). According to incomplete statistics 7 , thermal cracking caused by TMF accounts for approximately 80% of the total failure die-casting dies. Thus, good TMF behavior can prolong the service life of the hot work die. However, the literatures about TMF behavior of hot work die steel are rarely found. 5,6,8,9 As TMF tests are time consuming and require expensive equipment, the fatigue life prediction with varying Nomenclature: ϕ, mechanical strain/temperature true phase angle; Δε mech , mechanical strain range; Δε mech /2, mechanical strain amplitude; R ε , strain ratio; (ε mech ) max , maximum mechanical strain; (ε mech ) min , minimum mechanical strain; T 0 , reference temperature; T max , maximum temperature; T min , minimum temperature; σ max , maximum stress; σ min , minimum stress; σ m , mean stress; Δσ, st...

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Section: Resultsmentioning

confidence: 99%

Section: Cyclic Stress and Strain Response Behaviormentioning

confidence: 99%

In‐phase and out‐of‐phase thermomechanical fatigue behavior of 4Cr5MoSiV1 hot work die steel cycling from 400 °C to 700 °C

Pengpeng

Zeng

et al. 2017

Fatigue Fract Eng Mat Struct

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“…For plastic deformation, the left hand side of Eq. (11) can be rewritten as: at different levels of mean stress for 304 L stainless steel, SAE 1045 steel, 7075-T651 aluminum alloy, and Incoloy 901 superalloy [15][16][17][18]. The monotonic and fatigue properties of these metallic materials were tabulated, Table 2.…”

Section: The Walker Exponent Corrected Modelmentioning

confidence: 99%

A Walker exponent corrected model for estimating fatigue life of metallic materials in loading with mean stress

Qiu

et al. 2019

Materialwissenschaft Werkst

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Mean stress significantly influence the fatigue life predictions of metallic materials. The Walker mean stress equation with its additional material parameter w provides good predictions for a wide range of materials. Unfortunately, additional tests are necessary to determine the Walker exponent w. In order to overcome this shortcoming, for aluminum alloys, the Walker exponent w was correlated linearly with the sum of ultimate tensile strength and true fracture strength. Then, a Walker exponent corrected effective strain energy density criterion was developed by incorporating the Walker mean stress equation into the strain life curve. The capability of fatigue life prediction for the developed model was checked against the tested data of 304 L stainless steel, SAE 1045 steel, 7075‐T651 aluminum alloy, and Incoloy 901 superalloy, and comparisons were also performed by using the Lv's Walker exponent corrected model. The developed model provides more satisfactory results, especially for the considered materials in loading with mean stress.

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“…i) Temperature-strain phasing (IP or OP TMF) [24] ii) Maximum temperature extreme [21,25,28,29] iii) Minimum temperature extreme [21,25,28,29] iv) Mean Strain [30,31] v) Creep-fatigue interactions due to long dwells coupled with periodic TMF cycles [25,[32][33][34][35][36][37][38][39][40][41][42] vi) Elastic anisotropy due to crystal orientation [12,14,21,33,[43][44][45][46] vii) Over-aging of the microstructure during service conditions [18,[47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Parameters influencing thermomechanical fatigue of a directionally-solidified Ni-base superalloy

Kirka

Brindley

Neu

et al. 2015

International Journal of Fatigue

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Thermomechanical fatigue (TMF) is a low cycle fatigue process in which material life is correlated to the mechanical strain amplitude. However, it is well known that several other factors influence this life. This paper examines several of these parameters and their influence on life using experiments conducted on a second generation directionally-solidified (DS) Ni-base superalloy. The parameters considered include the influence of the temperature extremums (T max of either 750 or 950 • C and T min of either 100 or 500 • C), strain ratio (R ), the strain-temperature phasing (in-phase (IP) and out-of-phase (OP)), the influence of dwells at the high temperature end of the cycle resulting in a creep-fatigue (CF) interaction, and material anisotropy associated with the grain growth direction (longitudinal versus transverse). Results suggest that the phasing has a primary role in controlling the mechanism of degradation. IP TMF is dominated by crack formation in volumes surrounding debonded carbides for both continuously cycling (CC) and CF at 950 and 750 • C, while OP TMF is dominated by surface oxidation and repetitive cracking of the oxide that reforms at the crack tip at 950 • C. Decreasing the T max to 750 • C the environmental and creep effects are reduced resulting in virtually pure fatigue exposure under OP conditions. With decreasing T min from 500 • C to 100 • C was observed an increase in inelastic strain amplitude and 1 corresponding decrease in life. Variations in R were found to have no significant influence on life or stabilized stress behavior. TMF loading in the transverse orientation resulted in life reductions over the longitudinal orientation due to cracks propagating in a transgranular manner. Lastly, only in material exposed to CF with a T max of 950 • C rafting of the γ precipitates was observed.

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Mean stress models for low-cycle fatigue of a nickel-base superalloy

Cited by 41 publications

References 4 publications

In‐phase and out‐of‐phase thermomechanical fatigue behavior of 4Cr5MoSiV1 hot work die steel cycling from 400 °C to 700 °C

In‐phase and out‐of‐phase thermomechanical fatigue behavior of 4Cr5MoSiV1 hot work die steel cycling from 400 °C to 700 °C

A Walker exponent corrected model for estimating fatigue life of metallic materials in loading with mean stress

Parameters influencing thermomechanical fatigue of a directionally-solidified Ni-base superalloy

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