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Special Issue "Heat Resistant Steels and Alloys"

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A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: 31 July 2023 | Viewed by 5105

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Special Issue Editors

Prof. Dr. Satoru Kobayashi

E-Mail Website
Guest Editor

Tokyo Institute of Technology, Tokyo, Japan
Interests: microstructural design of heat-resistant steels and alloys; phase equilibria and phase transformations in metals and alloys; high-temperature deformation in metals and alloys.

Dr. Mikael Perrut

E-Mail Website
Guest Editor

DMAS, ONERA, Université Paris-Saclay, 92322 Châtillon, France
Interests: microstructure formation and evolution of Ni-based superalloys; alloy design; phase diagrams determination or calculation; metallurgy of intermetallics (such as titanium aluminides); solidification

Special Issue Information

Dear Colleagues,

Heat-resistant steels and alloys play important roles in high-temperature applications such as fossil fuel-fired power plants, chemical plants, airplane jet engines, etc. Despite the current strong pressure to exclude fossil fuel, especially coal, power generation, it is continuously important to make efforts to improve the heat resistance and long-term properties of the materials for higher efficiency of thermal power generation systems and also to design new materials that are adaptable to new operating conditions such as high-load fluctuation and supercritical carbon dioxide power cycles. The importance of designing new alloys and in understanding degradation mechanisms for improved jet engine operations remains unchanged due to the forecasted increase in the commercial aviation market until 2038.

This Special Issue highlights recent progress and innovations in the fields of heat-resistant steels and alloys from a wide perspective, including alloy design, characterization of microstructure formation and stability, creep deformation and fracture, creep-fatigue interaction, degradation mechanisms, oxidation, and high-temperature corrosion but not excluding other topics. This Special Issue focuses on metallic materials that include creep resistant ferritic and austenitic steels, superalloys, titanium alloys, intermetallic compounds, and refractory metals. Researchers are, therefore, encouraged to submit a research paper on their recent work but also a review paper on the topics.

Prof. Dr. Satoru Kobayashi
Dr. Mikael Perrut
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Alloy Design
Microstructure Formation, Evolution, and Stability
Creep Deformation and Fracture
Degradation Mechanisms
Creep Fatigue Interaction
Creep Resistant Ferritic and Austenitic Steels
Single Crystalline/Polycrystalline Superalloys for Blade/Disc Applications
Advanced Metallic Materials

Published Papers (5 papers)

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Research

Open AccessArticle

Effect of Solution Heat Treatment on the Porosity Growth of Nickel-Based P/M Superalloys

Hengyong Bu

Lu Chen

and

Yonghua Duan

Metals 2022, 12(11), 1973; https://doi.org/10.3390/met12111973 - 18 Nov 2022

Cited by 1 | Viewed by 538

Abstract

Thermal-induced porosity (TIP) is one of the major defects in powder metallurgy (P/M) superalloys, and it seriously affects the performance of P/M superalloys. The effects of solution heat treatment on the growth of the TIP of the nickel-based P/M superalloy FGH97 were investigated. A series of solution heat treatment tests were carried out at holding temperatures ranging from 1150 to 1200 °C, with holding times ranging from 0.5 to 8 h. The results showed that the holding time, temperature, and the initial volume of porosity are the primary factors influencing porosity growth, and the volume fraction of TIPs increases by increasing the temperature or extending the holding time. The porosity growth models were constructed based on the porosity statistics combined with a nonlinear fitting method. To evaluate the accuracy of the proposed models, the correlation coefficient (

R

) and average absolute relative error (

A A R E

) were calculated between the predicted and experimental values. The unbiased

A A R E

values were 2.06% and 3.99% for the average value of TIP and the worst value of TIP, respectively, which imply that the proposed porosity growth models have greater accuracy and can be used to illustrate TIP behavior in solution heat treatment. Full article

(This article belongs to the Special Issue Heat Resistant Steels and Alloys)

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Open AccessFeature PaperArticle

Grain Boundary Precipitation Control of GCP Phase Using TCP or A2 Phase in Ni-Based Alloys

and

Metals 2022, 12(11), 1817; https://doi.org/10.3390/met12111817 - 26 Oct 2022

Viewed by 1111

Abstract

To cover the grain boundary (GB) of the Ni phase with precipitates, the GB precipitation behavior of both topologically close-packed (TCP) or A2 and geometrically close-packed (GCP) phases was investigated in two Ni–Nb–(Co, Cr) ternary systems. The Ni/TCP or A2/GCP three-phase region existed in both systems. In the Ni-Nb-Co ternary system, Nb was approximately equally partitioned into both Co₇Nb₂ (mC18 structure, TCP) and (Ni, Co)₃Nb (D0₁₉ structure, GCP) phases. In the Ni–Nb-Cr ternary system, Nb and Cr were mainly partitioned into the Ni₃Nb (D0_a structure, GCP) and Cr (A2 structure) phases, respectively. In the Ni–Nb–Co ternary system, the Co₇Nb₂ phase grew along the GB, whereas the (Ni, Co)₃Nb phase grew toward the grain interior (GI). However, the growth of the Ni₃Nb phase toward the GI was suppressed in the Ni–Nb–Cr ternary system. The suppression of growth of the GCP phase and covering the GB using both the TCP or A2 and GCP phases might be possible in a system where the precipitation of the GCP phase nucleating on the GB prior to the TCP or A2 phase increases supersaturation for precipitation of the TCP or A2 phase. Full article

(This article belongs to the Special Issue Heat Resistant Steels and Alloys)

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Open AccessArticle

Alloying Effects on the Stability of D0₂₂ γ”-Ni₃M (M: Nb, Ta, V) Precipitates at Elevated Temperatures in Alloy 718 Type Ni-Based Alloys

Kako Tokutomi

Kyosuke Sagitani

and

Satoru Kobayashi

Metals 2022, 12(8), 1251; https://doi.org/10.3390/met12081251 - 26 Jul 2022

Viewed by 634

Abstract

The effects of alloying elements, M (M = Nb, Ta, and V), on the stability of D0₂₂ γ”-Ni₃M precipitates at elevated temperatures were investigated in Ni-22Cr-based ternary and quaternary alloys using heat-treated diffusion-multiple and bulk samples with discrete chemical compositions, with a final goal to improve the precipitate stability and the temperature capability of the Alloy-718-type Ni-based superalloys. Our microstructural characterization indicated that a complete replacement of Nb with Ta stabilized the γ” precipitates at temperatures up to 800 °C. A partial replacement of Ta with V was found to stabilize the precipitates even at 900 °C. Differential scanning calorimetry and high-temperature X-ray diffraction experiments demonstrated that the D0_a-Ni₃M structure was stable at elevated temperatures in the Ni-Cr-Ta ternary system. Lattice parameter measurements at room temperature suggested that a partial replacement of Ta with V decreased the lattice misfit between the fcc γ matrix and the γ” precipitate phases along the a- and c-axes of the tetragonal γ” crystal structure. The improved γ” precipitate stability was discussed in terms of the chemical driving force, misfit strain, and diffusion kinetics viewpoints. Full article

(This article belongs to the Special Issue Heat Resistant Steels and Alloys)

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Open AccessArticle

Role of Cr Content in Microstructure, Creep, and Oxidation Resistance of Alumina-Forming Austenitic Alloys at 850–900 °C

Yukinori Yamamoto

Qing-Qiang Ren

and

Michael P. Brady

Metals 2022, 12(5), 717; https://doi.org/10.3390/met12050717 - 23 Apr 2022

Viewed by 888

Abstract

Creep-rupture properties and oxidation behavior of a series of alumina-forming austenitic (AFA) alloys with variations of Cr contents, based on Fe-(13.5-18)Cr-25Ni-4Al-1.5Nb-0.1C in weight percent, have been evaluated at 850–900 °C. The study investigates material responses in the properties and microstructure through compositional modifications in AFA alloys, targeting performance optimization of alloys under high-temperature, corrosive industrial environments. The creep-rupture life of the alloys at 850 °C and 30MPa monotonically decreased with increasing Cr content, which was correlated with changes in secondary phase volume fractions, such as the reduction in B2-NiAl + Laves-Fe₂Nb and increase in Sigma-FeCr with Cr content. The oxidation test at 900 °C in a water-vapor containing environment revealed a range of Cr content from 13.9 to 15.7 wt.%, enabling the formation of stable, protective external alumina scale as well as preventing internal oxidation/nitridation for up to total 7000 h exposure. On the other hand, the alloys with >16.7 wt.% Cr formed Sigma precipitates, which caused a reduction in not only Cr but also Al in the austenite matrix, resulting in less oxidation resistance than other alloys. The findings will guide the further optimization of material performance in the AFA alloy series. Full article

(This article belongs to the Special Issue Heat Resistant Steels and Alloys)

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Open AccessFeature PaperArticle

Determination of Phase Equilibria among δ-Fe, γ-Fe and Fe₂M Phases in Fe-Cr-M (M: Hf, Ta) Ternary Systems

Zhetao Yuan

and

Satoru Kobayashi

Metals 2022, 12(1), 102; https://doi.org/10.3390/met12010102 - 05 Jan 2022

Cited by 1 | Viewed by 771

Abstract

Phase equilibria among δ-Fe, γ-Fe, and Fe₂M phases in the Fe-Cr-M (M: Hf, Ta) ternary systems were determined using bulk alloys heat-treated at high temperatures. The final goal of this study is to develop novel ferritic heat resistant steels strengthened by precipitation of Fe₂M phase on the eutectoid type reaction path: δ → γ + Fe₂M. The phases present in heat-treated samples were identified by microstructural characterization and X-ray diffraction pattern analysis. The chemical compositions of the phases were analyzed by energy dispersive spectroscopy. A pseudo-eutectoid trough (δ → γ + Fe₂M) exists at ~1220 °C at a Hf content of 0.1% and at ~1130 °C at a Ta content of 0.6% on the vertical section at a Cr content of 9.5% in each ternary system, respectively. A thermodynamic calculation with a database that reflects reported binary phase diagrams and the present study indicates that an increase in the Cr content decreases the temperature and the Hf/Ta contents of the pseudo-eutectoid troughs. The determined phase equilibria suggest that the supersaturation of Hf/Ta for the formation of γ phase is higher in the Hf doped system than in the Ta doped system, which is probably an origin of a much slower kinetics of precipitation on the eutectoid path in the latter system. Full article

(This article belongs to the Special Issue Heat Resistant Steels and Alloys)

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