Characterization of creep damage and lifetime in Inconel-713C nickel-based superalloy by stress-based, strain/strain rate-based and continuum damage mechanics models

Mohammadi

2020

IJE

In this paper, the short-term creep behavior of the Inconel-713C superalloy after different pre-treatments including the ageing and forging processes has been studied at 850 °C. The ageing heat treatment was heating at 930 °C for 16 hours without solutioning process. The optical microscopy (OM) and the scanning electron microscopy (SEM) techniques were applied for microstructural evaluations. The results showed that although the ageing treatment increased the γ' phase content, the age-hardened material had a lower creep lifetime (about 40%) with respect to the as-cast alloy. This was related to the decrease in the amount of M23C6-type secondary carbides precipitation. When the Inconel-713C superalloy specimen was forged at 1200 °C, the third stage of the creep curve (strain versus time) increased drastically and shortened the creep lifetime. The small grain size of the forged specimen was responsible for such inverse creep behavior. In addition, fractographs of this specimen indicated intragranular cracks on the ruptured surface. When the forged sample was age-hardened directly without the solutioning treatment, the creep lifetime increased about 4 times as compared to the forged specimen.

Section: Microstructral Evaluations After Creep Testingsupporting

confidence: 86%

“…This creep condition (the creep stress and temperature) was selected for better comparison of results of this paper with other results in our previous work [18][19]. Details of the utilized creep apparatus used in this study are found in previous works [18][19][20].…”

Section: Creep Test Conditionsmentioning

confidence: 99%

Effects of Ageing and Forging on Short-term Creep Behaviors of Inconel-713C Superalloy at 850 °C

Mohammadi

2020

IJE

“…To find the activation energy ( ) for the creep behavior in aluminum-silicon alloys, unreinforced and reinforced with nano-particles, the following equation could be used [50]:…”

Section: Resultsmentioning

confidence: 99%

Temperature Effect on Creep and Fracture Behaviors of Nano-SiO2-composite and AlSi12Cu3Ni2MgFe Aluminum Alloy

Aroo

2020

IJE

In the presented article, the temperature effect was studied on creep properties and fracture behaviors of AlSi12Cu3Ni2MgFe aluminum-silicon alloys, unreinforced and reinforced with SiO2 nano-particles. For such objective, standard specimens were fabricated by gravity casting and stir-casting methods, for aluminum alloys and nano-composites, respectively. Then, force-controlled creep testing was performed on standard specimens at 250, 275 and 300°C, under 100 MPa. Then, to find failure mechanisms, the fracture surface of test samples was also analyzed by the field emission scanning electron microscopy. Experimental results depicted the temperature changed creep behaviors of both materials, effectively. Moreover, a significant improvement in creep properties was observed by reinforcing the aluminum matrix with nano-particles, besides a heat treatment process. Such an increase in the creep lifetime was higher at 300°C. In addition, the fracture surface investigation of both materials implied the same brittle behavior, with quasi-cleavage marks. The failure location changed from inside the intermetallic phase into boundaries of the intermetallic phase in the nano-composite.

“…e second effect was the reduction of grain size from 300 μm to 130 μm for the AZ91 alloy and from 230 μm to 90 μm for the AZE911 alloy (using the ImageJ software), which caused a significant increase in the number of grain boundaries as well as the number of grains, which was the main reason for increasing the strength limit. erefore, logical agreements could be seen compared to the literature for these microstructural changes by heat-treating [8,18,25,26].…”

Section: Resultsmentioning

confidence: 57%

“…where σ a is stress amplitude, N f is fatigue lifetime, σ f ′ is the fatigue strength coefficient, and b stands for the fatigue , Nd [4], MM [28], and RE, (e) the HCF behavior of AZ91-T6 versus A319-T6 [29], and (f ) the HCF behavior of AZE911-T6 versus A356-T6 [25] and A380-T6 [26].…”

Section: Resultsmentioning

confidence: 99%

Effect of Heat-Treating on Microstructure and High Cycle Bending Fatigue Behavior of AZ91 and AZE911 Magnesium Alloys

Oliya

Advances in Materials Science and Engineering

Parast

et al. 2022

Self Cite

This article investigates the influences of heat-treating on the microstructures and the high cycle fatigue (HCF) properties of AZ91 and AZE911 (AZ91 + 1%RE) magnesium alloys. For such an objective, AZ91 and AZE911 alloys were used after solution treatment at 415°C for 5 hours aged at 215°C for 3 hours and at 215°C for 5 hours, respectively. To investigate the HCF behavior, a rotational bending fatigue test was performed with stress ratio (R) −1 and frequency of 100 Hz at room temperature. Optical microscopy (OM) study demonstrates that heat treatment leads to a reduction in grain size and transformation of continuous and discontinuous precipitations into needle-shaped precipitations, which are located on the grains of the alpha phase. Scanning electron microscopy (SEM) showed both marks of quasicleavage and cleavage on the fracture surface of specimens. These planes indicated the brittle behavior of the fracture. Moreover, in heat-treated specimens, the size of cleavage patterns was smaller, and microcracks were shorter. These behaviors affected the strength of the material and the fatigue lifetime. The results of mechanical tests show a negligible influence of heat-treating on the HCF behaviors of AZ91-T6 and AZE911-T6 alloys. Stress-lifetime curves (S-N) show an increase in fatigue strength in 3.8 × 105 fatigue cycles, from 95 MPa to 125 MPa for the AZ91-T6 alloy and from 125 MPa to 155 MPa for the AZE911-T6 alloy, after heat treatment.