Time–temperature superposition for foaming kinetics of Al-alloy foams

Kim, Amkee; Tunvir, K.; Nahm, Seung Hoon; Cho, Seong-Seock

doi:10.1016/j.jmatprotec.2007.10.001

Cited by 11 publications

(4 citation statements)

References 20 publications

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“…In this paper, the temperature and stress histories are divided at intervals of 1 s where Δtiand tCiare the duration time and creep rupture time of a randomized portion i after division, respectively. And in this investigation, the Manson–Succop stress-rupture equation (Kima and Tunvir, 2008; Ren and Shang, 2018; Zhuang and Huang, 2001) is adopted for multiaxial creep rupture time calculation, and the specific expression is as follows where T i and σCiare the equivalent celsius temperature and creep stress for multiaxial creep calculation, respectively . Other coefficients b 0 , b 1 , b 2 , b 3 , b 4 for GH4169 can be obtained by fitting the existing creep test data at different temperatures or can be directly obtained from Ren and Shang (2018)and Zhuang and Huang (2001).…”

Section: Proposed Life Prediction Methodsmentioning

confidence: 99%

“…where Át i and t Ci are the duration time and creep rupture time of a randomized portion i after division, respectively. And in this investigation, the Manson-Succop stress-rupture equation (Kima and Tunvir, 2008;Ren and Shang, 2018;Zhuang and Huang, 2001) is adopted for multiaxial creep rupture time calculation, and the specific expression is as follows…”

Section: Calculation Of Creep Damagementioning

confidence: 99%

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Thermomechanical fatigue life prediction method for nickel-based superalloy in aeroengine turbine discs under multiaxial loading

Shang

Zhang

et al. 2019

International Journal of Damage Mechanics

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The multiaxial thermomechanical fatigue properties for nickel-based superalloy GH4169 in aeroengine turbine discs are investigated in this paper. Four types of axial–torsional thermomechanical fatigue experiments were performed to identify the cyclic deformation behavior and the damage mechanism. The experimental results showed that the creep damage can be generated under thermally in-phase loading while it can be ignored under thermally out-of-phase loading, and the responded stress increasing phenomenon, that is, non-proportional hardening, can be shown under the mechanically out-of-phase strain loading. Based on the analysis of cyclic deformation behavior and damage mechanism, a life prediction method was proposed for multiaxial thermomechanical fatigue, in which the pure fatigue damage, the creep damage, and the interaction between them were simultaneously considered. The pure fatigue damage can be calculated by the isothermal fatigue parameters corresponding to the temperature without creep; the creep damage can be calculated by the principle of subdivision, and the creep–fatigue interaction can be determined by creep damage, fatigue damage, and an interaction coefficient which is used to reflect the creep–fatigue interaction strength. The predicted results showed that the proposed method is reasonable.

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Section: Proposed Life Prediction Methodsmentioning

confidence: 99%

Section: Calculation Of Creep Damagementioning

confidence: 99%

Thermomechanical fatigue life prediction method for nickel-based superalloy in aeroengine turbine discs under multiaxial loading

Shang

Zhang

et al. 2019

International Journal of Damage Mechanics

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“…These techniques represent the master curves which involve stress (σ), temperature (T) and rupture time (t R ). Among these parametric techniques, Larson-Miller parameter (P L-M ) is the most commonly used method to determine creep life [9,10,11,12,13]. P L-M is expressed by the relationship:…”

Section: Introductionmentioning

confidence: 99%

Investigation of Micro-structure and Creep Life Analysis of Centrifugally Cast Fe–Cr–Ni Alloy Reformer Tubes

Ghatak¹,

Robi²

2015

mst

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Reformer furnace tubes are designed for exposure to high temperatures and pressures for prolonged time. HP grade steels which are cast austenitic Fe-Cr-Ni alloys are used as reformer tubes for service temperatures in the range of 950°C to 1000°C. This paper reports an investigation on the results of analysis of service exposed HP40Nb steel micro-alloyed with Ti. Microstructural investigation of the service exposed tube revealed carbides rich in Cr, Nb and Ti at grain boundary regions which are typical features of the cast material. No evidence of creep deformation was observed in this material indicating absence of degradation in structure and properties. Accelerated stress rupture tests at temperatures in the range of 850°C-1050°C and stress in the range of 47 MPa-80 MPa on samples machined from tubes exposed for 11 years at 650°C was carried out to assess the life of the tube for various combinations of temperature and stress by Larson-Miller parameter. Observation of the fractured samples after accelerated stress rupture tests revealed nucleation and growth of voids at Cr rich phases as the main mechanism of damage at elevated temperatures. This paper also discusses the need for using the Larson-Miller constant (C L-M) as a function of stress rather than considering it as a constant value.

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“…Although several methods to fabricate metal foams exist, it is still difficult to obtain a homogenous structure with uniform properties [7]. Most studies have focused on the thermodynamic instability of gas expansion in the melt as non-uniform pores exist because the bubble usually undergoes growth, amalgamation and disintegration in the molten aluminum metal [8][9][10]. On the other hand, it has been reported that the presence of particles in the molten metal helps to stabilize the foam by allowing for accumulation on cell walls [7].…”

Section: Introductionmentioning

confidence: 99%