Very-high-cycle fatigue behavior of AlSi10Mg manufactured by selective laser melting: Effect of build orientation and mean stress

In the present study, the relationship between heat treatment, grain size, and the creep rupture properties of Fe-33Ni-19Cr alloy was investigated. The microstructure analysis showed that Fe-33Ni-19Cr alloy consists of the austenite phase matrix and a small number of precipitates such as titanium nitride and titanium carbides. Fe-33Ni-19Cr alloy shows an increase in steady-state creep rate with increased grain size from 94 to 381 μm, due to the grain boundary sliding mechanism. The result also exhibited that the alloy that was subjected to creep test failed in ductile mode and cavitation at the grain boundaries. The fracture surface shows a transgranular fracture but an intergranular fracture at the recrystallized grains at the fracture area. Taken together, the result exhibited that the Fe-33Ni-19Cr alloy subjected lower heat treatment temperature possess a smaller grain size, which led to better creep property along with more excellent service life during operation.A superalloy is an alloy capable of withstanding high stresses and often highly oxidizing atmosphere and high temperatures, which often reach extreme temperatures surpassing 1200 C. 1 These harsh environments caused creep to be a serious issue when the alloys are used at high temperatures. Superalloys based on iron (Fe), nickel (Ni), and cobalt (Co) can be engineered to be highly resistant to creep. 2 Thus, superalloys have arisen as an ideal material to be used in high-temperature environments. Fe-Ni-Cr alloy is a solid solution strengthening ironnickel-based heat-resistant steel. 3 They are widely used in high-temperature environments, such as steam generator tubes, nuclear power reaction tubes, gas turbines, petrochemical and refinery industries, reformer tubes, furnace components, and pyrolysis tubes. 4 The operating temperature of the modern power plant is up to 760 C, and the steam pressures are more than 35 MPa. High-temperature failure mechanism includes creep,

Section: Microstructure Evolution During Creepingsupporting

confidence: 80%

Relationship between the microstructure and the heat treatment and creep behavior of Fe–33Ni–19Cr alloy

Mudang

Hamzah

Bakhsheshi‐Rad

et al. 2021

“…In this section, the experimental results on aluminum alloys available in the literature are analyzed. In Qian et al, 31 ultrasonic fatigue tests were carried out on AlSi10Mg specimens produced through an SLM process to investigate the effect of the stress ratio and of the building direction up to 10 9 cycles. Fatigue tests were carried out at a load frequency of 20 kHz on specimens produced in the XY and in Z direction and at stress ratio R equal to −1, 0 and 0.5.…”

Section: Aluminum Alloysmentioning

confidence: 99%

Fatigue failures from defects in additive manufactured components: A statistical methodology for the analysis of the experimental results

Tridello

Niutta

Berto

et al. 2021

Self Cite

The fatigue response of additive manufactured (AMed) components is generally controlled by the defect population, and the models for assessing the fatigue response of AMed parts have to take into account the distribution of defect size and the intrinsic scatter associated to the fatigue response. In the present paper, a statistical methodology for analyzing the results of tests on AMed specimens failed due to cracks originating from defects is proposed. The procedure involves the estimation of the distribution of the fatigue life, which is considered dependent on the applied stress amplitude and on the defect size. Thereafter, all the experimental failures are shifted at a reference number of cycles to failure or stress amplitude, making it possible to compare data obtained at different stress levels or number of cycles to failure. The proposed method has been successfully validated on literature dataset, proving its effectiveness and general validity.

“…The weakest site in fatigue is generally represented by a defect (inclusion, pore, matrix inhomogeneity) that acts as an initial crack 16,17 in the loaded material volume. This is well known in the fatigue literature (see, e.g., the works on manufacturing defects in cast irons 18–24 and additive materials 25–30 ). The defect population drives the VHCF response of materials, and according to Murakami, 17,31,32 the defect size is the main responsible for the VHCF failure.…”

Section: Introductionmentioning

confidence: 87%

Very high cycle fatigue life and critical defect size: Modeling of statistical size effects

Paolino

2021

A novel statistical approach to model size effects in very high cycle fatigue (VHCF) is proposed in the paper. The statistical distributions of the VHCF life and of the size of the defect leading to VHCF failure (critical defect) are identified in the paper through the weakest‐link principle. The statistical distributions are able to account for the stress gradients that are present in a loaded material volume. An efficient procedure for estimating the parameters involved in the statistical distributions is also shown. The proposed statistical models are finally validated through experimental data taken from the literature. The experimental validation proves the fitting capability of the proposed models that outperform the traditional models based on the 90% risk‐volume.