Phase instabilities during high temperature exposure of 316 austenitic stainless steel
01 Apr 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science (Springer New York)-Vol. 3, Iss: 4, pp 851-866
TL;DR: In this paper, time-temperature-precipitation diagrams were determined between 400° and 900°C for up to 3000 hr as a function of carbon content, solution treatment temperature, and cold work.
Abstract: Although Type 316 austenitic stainless steel is widely used in steam generating plants and nuclear reactors the knowledge about aging reactions, nature of precipitates, and precipitation kinetics during high temperature exposure is limited. Time-temperature-precipitation (TTP) diagrams were determined between 400° and 900°C for up to 3000 hr as a function of carbon content, solution treatment temperature, and cold work. The nucleation and growth phenomena, morphology, and composition of the various carbide (M23C6, M6C) and intermetallic phases (σ, χ, η were determined. The complex sequence of phase instabilities can be explained on the basis of the carbon content, effect of molybdenum and chromium on the carbon solubility, thermodynamic stability of the phases, and the kinetics of the various precipitation reactions.
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TL;DR: In this paper, a review focusing on precipitation in creep resistant austenitic stainless steels, in particular wrought heat resistant grades containing niobium and titanium additions, is presented.
Abstract: Austenitic stainless steels have for some time been used as superheater tubes in the electricity generation industries in harsh environments with temperatures as high as 650°C at pressures of some 200 atm; they are expected to provide reliable service for 30 years or more. Their detailed mechanical properties are dependent on the stability of the microstructure, particularly the formation, dissolution, and coarsening of precipitates. Although the precipitation processes have been studied extensively, there remain important discrepancies. It is known that small changes in the chemical composition or thermomechanical processing can profoundly influence the evolution of the microstructure. This review focuses on precipitation in creep resistant austenitic stainless steels, in particular wrought heat resistant grades containing niobium and titanium additions. Conventional alloys such as 18–8 and 16–10 are included together with the new NF709 (20–25) and other recent variants. Precipitates forming in a...
583 citations
TL;DR: In this paper, a component built from 304L stainless steel incrementally graded to Inconel 625 was characterized by microscopy, chemistry, phase composition, and microhardness as a function of position.
376 citations
TL;DR: In this paper, a brief introduction to the development and the precipitation characteristics (including morphologies and precipitation sites) of the 𝜎 phase in stainless steels is presented.
Abstract: The 𝜎 phase which exists in various series of stainless steels is a significant subject in steels science and engineering. The precipitation of the 𝜎 phase is also a widely discussed aspect of the science and technology of stainless steels. The microstructural variation, precipitation mechanism, prediction method, and effects of properties of 𝜎 phase are also of importance in academic discussions. In the first section, a brief introduction to the development and the precipitation characteristics (including morphologies and precipitation sites) of 𝜎 phase in stainless steels is presented. In the second section, the properties effect, prediction method, processing effect, elemental addition, retardation method and Thermo-Calc simulation of the 𝜎 phase in stainless steels are highlighted.
353 citations
Cites background from "Phase instabilities during high tem..."
...Padilha and Rios [22] pointed out that the σ phase precipitating directly in γaustenite was very slow (about several thousand hours) [23]....
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07 Mar 2018-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, high-density 316 L specimens were fabricated by selective laser melting (SLM) and different processing parameters, including laser power (100, 200 W) and scanning strategies (alternating stripes without and with remelting after every layer) were employed to evaluate their impact on microstructure and texture of the specimens.
Abstract: High-density 316 L specimens were fabricated by selective laser melting (SLM). Different processing parameters, including laser power (100, 200 W) and scanning strategies (alternating stripes without and with re-melting after every layer) were employed to evaluate their impact on microstructure and texture of the specimens. Microstructures of the specimens in as-built condition were characterised by columnar grains of austenite with intercellular segregation of Mo, Cr and Si, resulting in creation of non-equilibrium eutectic ferrite. It was found that laser energy density and scanning strategy strongly affect cellular substructure of austenite and amount of ferrite, as well as kind and degree of texture. Specific microstructure of austenite in as-built condition is the cause of almost double increase of yield strength accompanied by much smaller improvement of ultimate tensile strength and 1.4 times reduction of elongation at fracture in comparison of properties of hot-rolled SS316L sheet. Moreover, features of this substructure determine kind of the changes occurring during stress relieving at 800 °C for 5 h (among others, precipitation of sigma-phase strongly activated by presence of ferrite and residual stresses), demonstrated by decreased yield strength value with no significant changes of ultimate tensile strength and elongation. At the same time, an attempt was made to explain some unclearly interpreted observations in the literature related to a correlation between process parameters, microstructure and properties of SLM-processed steel 316 L.
297 citations
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01 Apr 1985TL;DR: In this paper, a systematic review of experimentals observations of irradiation-altered phase stability is presented, including enhanced nucleation on displacement cascades, precipitation induced by solute segregation to defect sinks, nucleation of wrong phases, disordering and amorphization, Frenkel pair recombination driven precipitate, and inverse Ostwald ripening.
Abstract: Irradiation of metals and alloys with neutrons, electrons, heavy ions, or γ-rays may introduce up to 108 J/mol of energy in the form of atomic displacements. This energy, which is in the form of vacancies, self-interstitials, and cores of displacement cascades is then available to produce a range of phase changes and microstructural alterations which are not observed under thermal conditions. There exist numerous mechanisms to convert part of this displacement energy into microstructural change, including irradiation-induced solute segregation, Frenkel pair recombination at the particle: matrix interface, irradiation disordering or amorphization, and recoil resolution of atoms from precipitates. In addition, the cores of displacement cascades may act as precipitate nucleation sites and Frenkel pair recombination may trigger spinodal-like instabilities. The theory of these mechanisms is developed in some detail, and is followed by a systematic review of experimentals observations of irradiation-altered phase stability. The observations include enhanced nucleation on displacement cascades, precipitation induced by solute segregation to defect sinks, nucleation of wrong phases, disordering and amorphization, Frenkel pair recombination driven precipitate, and inverse Ostwald ripening.
275 citations
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01 Jun 1977
TL;DR: Hirsch et al. as mentioned in this paper described further experiments on the preparation of thin film sections of embedded Backscatter Kikuchi diffraction in the SEM for identification of crystallographic thin films by electron microscopy.
Abstract: In continuation of an earlier publication (Hoppe et al., 1968), further experiments are described here on the preparation of thin film sections of embedded Backscatter Kikuchi diffraction in the SEM for identification of crystallographic thin films by electron microscopy Peter B. Hirsch, Electron Works by Peter B. Hirsch: Electron Microscopy of Thin Crystals Peter B. Hirsch Author of Electron Microscopy of Thin Crystals
4,077 citations
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01 Jan 1958
TL;DR: The Handbook of Lattice spacings and structures of metals and alloys as discussed by the authors is a handbook of argumentative essay structure spacing and lattice plane model modified by the incorporation of thermodynamic functions appropriate to the f.c.
Abstract: For the best product experience, a Handbook of of argumentative essay structure spacing Lattice Spacings and Structures of Metals and Alloys ScienceDirect. Get this from a library! A handbook of lattice spacings and structures of metals and alloys. (W B Pearson) Acm metal). Vol. lattice plane model modified by the incorporation of thermodynamic functions appropriate to the f.c.c. Al—Ag solid zones in the alloys. W. B. Pearson, Handbook of Lattice Spacings. Structures of Metals and Alloys.
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51 citations
01 Apr 1969
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