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3 pages, 172 KiB

Open AccessEditorial

Creep and Deformation of Metals and Alloys at Elevated Temperatures

by Nadezhda Dudova

Metals 2021, 11(11), 1837; https://doi.org/10.3390/met11111837 - 16 Nov 2021

Viewed by 1856

Abstract

Various aspects of creep and deformation behaviors of metals and alloys at elevated temperatures are of great interest to materials scientists [...] Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

Research

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24 pages, 10336 KiB

Open AccessArticle

316L(N) Creep Modeling with Phenomenological Approach and Artificial Intelligence Based Methods

by Daniele Baraldi, Stefan Holmström, Karl-Fredrik Nilsson, Matthias Bruchhausen and Igor Simonovski

Metals 2021, 11(5), 698; https://doi.org/10.3390/met11050698 - 24 Apr 2021

Cited by 4 | Viewed by 2422

Abstract

A model that describes creep behavior is essential in the design or life assessment of components and systems that operate at high temperatures. Using the RCC-MRx data and the LCSP (logistic creep strain prediction) model, processed design data were generated over the whole [...] Read more.

A model that describes creep behavior is essential in the design or life assessment of components and systems that operate at high temperatures. Using the RCC-MRx data and the LCSP (logistic creep strain prediction) model, processed design data were generated over the whole creep regime of 316L(N) steel—i.e., primary, secondary, and tertiary creep. The processed design data were used to develop three models with different approaches for the creep rate: a phenomenological approach; an artificial neural network; and an artificial intelligence method based on symbolic regression and genetic programming. It was shown that all three models are capable of describing the true creep rate as a function of true creep strain and true stress over a wide range of engineering stresses and temperatures without the need of additional micro-structural information. Furthermore, the results of finite element simulations reproduce the trends of experimental data from the literature. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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18 pages, 15262 KiB

Open AccessArticle

Normalized Parameter Creep Model of DD6 Nickel-Based Single Crystal Superalloy

by Dasheng Wei, Yihui Liu, Yanrong Wang, Jialiang Wang and Xianghua Jiang

Metals 2021, 11(2), 254; https://doi.org/10.3390/met11020254 - 2 Feb 2021

Cited by 8 | Viewed by 2595

Abstract

For nickel-based single crystal superalloy DD6 (AECC Beijing Institute of Aeronautical Materials, Beijing, China) material, a method for predicting creep rupture time was proposed based on a newly defined equivalent stress method. An anisotropic creep model for describing the orientation-dependent creep behavior and [...] Read more.

For nickel-based single crystal superalloy DD6 (AECC Beijing Institute of Aeronautical Materials, Beijing, China) material, a method for predicting creep rupture time was proposed based on a newly defined equivalent stress method. An anisotropic creep model for describing the orientation-dependent creep behavior and lifetime of a nickel-based single crystal superalloy was proposed. The creep subroutine was written based on the proposed nickel-based single crystal creep model. The stability of the model was improved by adjusting the iterative algorithm. The creep calculation results in [001], [011], and [111] loading directions were compared with the experimental results. The accuracy of the calculation results by the nickel-based single crystal creep subroutine was verified. The initial time step and maximum time step of the creep subroutine were studied. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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16 pages, 5924 KiB

Open AccessArticle

High Temperature Creep Behaviour of Cast Nickel-Based Superalloys INC 713 LC, B1914 and MAR-M247

by Marie Kvapilova, Petr Kral, Jiri Dvorak and Vaclav Sklenicka

Metals 2021, 11(1), 152; https://doi.org/10.3390/met11010152 - 14 Jan 2021

Cited by 8 | Viewed by 5134

Abstract

Cast nickel-based superalloys INC713 LC, B1914 and MAR-M247 are widely used for high temperature components in the aerospace, automotive and power industries due to their good castability, high level of strength properties at high temperature and hot corrosion resistance. The present study is [...] Read more.

Cast nickel-based superalloys INC713 LC, B1914 and MAR-M247 are widely used for high temperature components in the aerospace, automotive and power industries due to their good castability, high level of strength properties at high temperature and hot corrosion resistance. The present study is focused on the mutual comparison of the creep properties of the above-mentioned superalloys, their creep and fracture behaviour and the identification of creep deformation mechanism(s). Standard constant load uniaxial creep tests were carried out up to the rupture at applied stress ranging from 150 to 700 MPa and temperatures of 800–1000 °C. The experimentally determined values of the stress exponent of the minimum creep rate, n, were rationalized by considering the existence of the threshold stress, σ₀. The corrected values of the stress exponent correspond to the power-law creep regime and suggest dislocation climb and glide as dominating creep deformation mechanisms. Fractographic observations clearly indicate that the creep fracture is a brittle mostly mixed transgranular and intergranular mode, resulting in relatively low values of fracture strain. Determined main creep parameters show that the superalloy MAR-M247 exhibits the best creep properties, followed by B1914 and then the superalloy INC713 LC. However, that each of the investigated superalloys can be successfully used for high temperature components fulfils the required service loading conditions. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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19 pages, 11410 KiB

Open AccessFeature PaperArticle

Effect of Alloying on the Nucleation and Growth of Laves Phase in the 9–10%Cr-3%Co Martensitic Steels during Creep

by Alexandra Fedoseeva, Ivan Nikitin, Evgeniy Tkachev, Roman Mishnev, Nadezhda Dudova and Rustam Kaibyshev

Metals 2021, 11(1), 60; https://doi.org/10.3390/met11010060 - 30 Dec 2020

Cited by 23 | Viewed by 2274

Abstract

Five Co-modified P92-type steels with different contents of Cr, W, Mo, B, N, and Re have been examined to evaluate the effect of the chemical composition on the evolution of Laves phase during creep at 650 °C. The creep tests have been carried [...] Read more.

Five Co-modified P92-type steels with different contents of Cr, W, Mo, B, N, and Re have been examined to evaluate the effect of the chemical composition on the evolution of Laves phase during creep at 650 °C. The creep tests have been carried out at 650 °C under various applied initial stresses ranging from 80 to 200 MPa until rupture. An increase in the B and Cr contents leads to a decrease in the size and volume fraction of M₂₃C₆ carbides precipitated during tempering and an increase in their number particle density along the boundaries. In turns, this affects the amount of the nucleation sites for Laves phase during creep. The (W+Mo) content determines the diffusion growth and coarsening of Laves phase during creep. Susceptibility of Laves phase to coarsening with a high rate is caused by the large difference in Gibbs energy between fine and large particles located at the low-angle and high-angle boundaries, respectively, and can cause the creep strength breakdown. The addition of Re to the 10%Cr steel with low N and high B contents provides the slowest coarsening of Laves phase among the steels studied. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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11 pages, 31318 KiB

Open AccessArticle

Influence of Forging and Heat Treatment on the Microstructure and Mechanical Properties of a Heavily Alloyed Ingot-Metallurgy Nickel-Based Superalloy

by Valery Imayev, Shamil Mukhtarov, Kamilla Mukhtarova, Artem Ganeev, Ruslan Shakhov, Nikolay Parkhimovich and Aleksander Logunov

Metals 2020, 10(12), 1606; https://doi.org/10.3390/met10121606 - 30 Nov 2020

Cited by 5 | Viewed by 2512

Abstract

The newly designed ingot-metallurgy nickel-based superalloy SDZhS-15 intended for disc applications at operating temperatures up to 800–850 °C was subjected to homogenization annealing and canned forging at subsolvus temperatures, followed by solid solution treatment and ageing. Mostly a fine-grained recrystallized microstructure was obtained [...] Read more.

The newly designed ingot-metallurgy nickel-based superalloy SDZhS-15 intended for disc applications at operating temperatures up to 800–850 °C was subjected to homogenization annealing and canned forging at subsolvus temperatures, followed by solid solution treatment and ageing. Mostly a fine-grained recrystallized microstructure was obtained in the forgings. It was revealed that post-forging solid solution treatment at T > (T_s-50), where T_s is the γ′ solvus temperature, led to a significant γ grain growth, which in turn led to a decrease in strength and ductility of the superalloy. The solution treatment at (T_s-60)–(T_s-50) allowed to save fine γ grains (d_γ = 10–20 μm) and to provide the formation of secondary γ′ precipitates with a size of around 0.1 μm. In the forged and heat-treated conditions, the superalloy demonstrated superior mechanical properties, particularly excellent creep resistance at 650–850 °C in the stress range of 400–1200 MPa. Microstructure examination of the creep-tested samples showed that a decrease in the creep resistance at 850 °C can be associated with enhanced diffusivity along γ grain and γ/γ′ interphase boundaries leading to formation of cracks along the boundaries. In spite of the heavy alloying, the topologically close-packed phases were not detected in the superalloy, including in the creep tested samples. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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14 pages, 4796 KiB

Open AccessArticle

Cyclic Creep Behavior and Modified Life Prediction of Bainite 2.25Cr-1Mo Steel at 455 °C

by Hao Jiang, Oluwadamilola Ogunmola, Zizhen Zhao, Bingbing Li and Xu Chen

Metals 2020, 10(11), 1486; https://doi.org/10.3390/met10111486 - 6 Nov 2020

Cited by 3 | Viewed by 2090

Abstract

Uniaxial static and cyclic creep tests were carried out on bainite 2.25Cr-1Mo steel at 455 °C. Effects of the unloading rate from 0.6 to 39 MPa/s and valley stress duration from 0 to 30 min on the cyclic creep deformation behavior were discussed. [...] Read more.

Uniaxial static and cyclic creep tests were carried out on bainite 2.25Cr-1Mo steel at 455 °C. Effects of the unloading rate from 0.6 to 39 MPa/s and valley stress duration from 0 to 30 min on the cyclic creep deformation behavior were discussed. The results indicated that the fracture behavior under static and cyclic creep conditions showed a consistent ductile mode. The strain accumulation rate under cyclic creep was significantly retarded as compared with static creep due to the presence of anelastic recovery which was apparently influenced by the unloading conditions. For cyclic creep tests, the unrecoverable strain component determined by a systematic classification of the stress–strain curve was the true damage. A modified life prediction method proposed based on the unrecoverable strain component presented a good life prediction for cyclic creep. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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13 pages, 24159 KiB

Open AccessArticle

Temperature Dependent Solid Solution Strengthening in the High Entropy Alloy CrMnFeCoNi in Single Crystalline State

by Christian Gadelmeier, Sebastian Haas, Tim Lienig, Anna Manzoni, Michael Feuerbacher and Uwe Glatzel

Metals 2020, 10(11), 1412; https://doi.org/10.3390/met10111412 - 23 Oct 2020

Cited by 14 | Viewed by 3606

Abstract

The main difference between high entropy alloys and conventional alloys is the solid solution strengthening effect, which shifts from a single element to a multi-element matrix. Little is known about the effectiveness of this effect at high temperatures. Face-centered cubic, equiatomic, and single [...] Read more.

The main difference between high entropy alloys and conventional alloys is the solid solution strengthening effect, which shifts from a single element to a multi-element matrix. Little is known about the effectiveness of this effect at high temperatures. Face-centered cubic, equiatomic, and single crystalline high entropy alloy CrMnFeCoNi was pre-alloyed by arc-melting and cast as a single crystal using the Bridgman process. Mechanical characterization by creep testing were performed at temperatures of 700, 980, 1100, and 1200 °C at different loads under vacuum and compared to single-crystalline pure nickel. The results allow a direct assessment of the influence of the chemical composition without any disturbance by grain boundary sliding or diffusion. The results indicate different behaviors of single crystalline pure nickel and CrMnFeCoNi. At 700 °C CrMnFeCoNi is more creep-resistant than Ni, but at 980 °C both alloys show a nearly similar creep strength. Above 980 °C the creep behavior is identical and the solid solution strengthening effect of the CrMnFeCoNi alloy disappears. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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17 pages, 6067 KiB

Open AccessFeature PaperArticle

On Temperature Dependence of Microstructure, Deformation Mechanisms and Tensile Properties in Austenitic Cr-Mn Steel with Ultrahigh Interstitial Content C + N = 1.9 Mass.%

by Elena Astafurova, Sergey Astafurov, Galina Maier, Irina Tumbusova, Eugene Melnikov, Valentina Moskvina, Marina Panchenko, Kseniya Reunova and Nina Galchenko

Metals 2020, 10(6), 786; https://doi.org/10.3390/met10060786 - 13 Jun 2020

Cited by 1 | Viewed by 2442

Abstract

The microstructure, deformation mechanisms, tensile properties and fracture micromechanisms of ultrahigh-interstitial austenitic Fe-22Cr-26Mn-1.3V-0.7C-1.2N (mass.%) steel were investigated in wide temperature interval. After conventional homogenization and solid-solution treatment, the steel possesses complex hardening which includes grain boundary, solid-solution and dispersion strengthening. In the temperature [...] Read more.

The microstructure, deformation mechanisms, tensile properties and fracture micromechanisms of ultrahigh-interstitial austenitic Fe-22Cr-26Mn-1.3V-0.7C-1.2N (mass.%) steel were investigated in wide temperature interval. After conventional homogenization and solid-solution treatment, the steel possesses complex hardening which includes grain boundary, solid-solution and dispersion strengthening. In the temperature interval of −60 to +60 °C, steel demonstrates striking temperature dependence of a yield strength which could be enhanced by the increase in solid-solution treatment temperature. The variation in test temperature does not change the dominating deformation mechanism of the steel, dislocation slip and insufficiently influences tensile elongation and fracture micromechanisms. The insignificant increase in the fraction of brittle cleavage-like component on the fracture surfaces of the specimens in low-temperature deformation regime is promoted by increase in planarity of dislocation arrangement and the gaining activity of mechanical twinning. In high-temperature range (200–300 °C) of deformation, a negative strain-rate dependence, serrations on the stress-strain diagrams and improved strain-hardening associated with a dynamic strain aging phenomenon have been observed. Full article

(This article belongs to the Special Issue Creep and Deformation of Metals and Alloys at Elevated Temperatures)

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