Development of a New Austenitic Stainless Steel (Low-C-18Cr-11Ni-3Cu-Mo-Nb-B-N) With High Sensitization Resistance and High Temperature Strength

2019 ◽  
Author(s):  
Yuhei Suzuki ◽  
Shogo Aota ◽  
Etsuo Dan ◽  
Masaki Ueyama ◽  
Takahiro Osuki ◽  
...  
Keyword(s):  
High Temperature ◽  
High Ratio ◽  
M23c6 Carbide ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Low Carbon ◽  
Intergranular Stress Corrosion ◽  
Creep Ductility ◽  
Acid Environment ◽  
Intergranular Stress Corrosion Cracking

Abstract Austenitic materials with high sensitization resistance and high temperature strength are required for furnace and reaction tower of desulfurizing plants in the petroleum refinery industry. For these requirements, a new steel (LowC-18Cr-11Ni-3Cu-Mo-Nb-B-N) has been developed. The steel shows no intergranular stress corrosion cracking in polythionic acid environment after aging in the temperature range from 565 to 700 °C for up to 10,000 hours. This excellent PTA-SCC resistance is attributed to the prevention of M23C6 carbide precipitation along grain boundary due to extra low carbon content with high ratio of niobium to carbon. The maximum allowable tensile stress of this steel is estimated to be more than 30% higher than that of ASME SA213 Type347H. This excellent strength is based on the precipitation strengthening effect due to fine precipitates of a copper rich phase which are coherent with the austenite matrix in addition to Z-phase (NbCrN). Moreover, boron addition improves creep strength and creep ductility of the steel. From these results, it is concluded that the newly developed steel is a promising material not only for refinery processes but also for other elevated temperature usages.

Influence of Thermo-Mechanical Processing on the Microstructure of Beryllia Dispersed Nickel Alloys

1973 ◽  
Vol 31 ◽  
pp. 184-185
Author(s):  
M.S. Grewal ◽  
S.A. Sastri ◽  
N.J. Grant
Keyword(s):  
High Temperature ◽  
Nickel Alloys ◽  
Thermomechanical Processing ◽  
Cold Work ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Mechanical Processing ◽  
Uniform Dispersion ◽  
Oxide Particles ◽  
Nickel Base

Currently there is a great interest in developing nickel base alloys with fine and uniform dispersion of stable oxide particles, for high temperature applications. It is well known that the high temperature strength and stability of an oxide dispersed alloy can be greatly improved by appropriate thermomechanical processing, but the mechanism of this strengthening effect is not well understood. This investigation was undertaken to study the dislocation substructures formed in beryllia dispersed nickel alloys as a function of cold work both with and without intermediate anneals. Two alloys, one Ni-lv/oBeo and other Ni-4.5Mo-30Co-2v/oBeo were investigated. The influence of the substructures produced by Thermo-Mechanical Processing (TMP) on the high temperature creep properties of these alloys was also evaluated.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

Investigation of Oxide-Nucleation on Ferritic FeCr Interconnect Alloys for Solid Oxide Fuel Cells Exposed to Anode and Cathode Gases at 850°C

2008 ◽  
Vol 595-598 ◽  
pp. 779-787
Author(s):  
Georg Kunschert ◽  
Hans Peter Martinz ◽  
Michael Schütze
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Thermal Cycling ◽  
Oxide Scale ◽  
Cross Sections ◽  
Scale Formation ◽  
Solid Oxide ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Fuel

In recent years solid-oxide fuel cell (SOFC) interconnect components have proven to be a key-component accountable for the functionality of high temperature fuel cells. Amongst adequate thermal expansion and high temperature strength, highest oxidation resistance in anode and cathode gases under thermal cycling conditions is required in order to reach long term durability, particularly when using thin film light-weight components with particular focus on automotive applications. In order to match the challenging parameter profile Plansee developed the mechanically alloyed ITM, a ferritic P/M Fe26Cr alloy strengthened with additions of Y2O3 dispersoids, since it has been observed that apart from their HT strengthening effect, which is of specific interest for thin sheets components, finest ODS particles reduce the growth and enhance the adhesion of the forming oxide layers. The latter effect is of particular interest in applications where alloys are exposed to HT cyclic conditions. In this work the nucleation phase of the oxide scale formation on P/M ODS Fe26Cr ITM is compared to that on a reference ingot steel Fe22Cr in typical anode gases containing significant amounts of H2, CO and approximately 3% H2O as well as in laboratory air at 850°C. Thermal cycling oxidation tests following the COTEST standard up to 168h are carried out in both environments. Moreover cyclic oxidation tests are performed in dry anode gas. Detailed studies of oxide scale formation and evolution by means of electron microscopy of cross sections as well as oxide surfaces are undertaken.

scholarly journals Metallurgical Evaluation of an Additively Manufactured Nickel-Base Superalloy for Gas Turbine Guide Vanes

2020 ◽  
Author(s):  
Alex Bridges ◽  
John Shingledecker ◽  
Alex Torkaman ◽  
Lonnie Houck
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Rupture Strength ◽  
Creep Rupture ◽  
M23c6 Carbide ◽  
Nickel Base Superalloy ◽  
Creep Ductility ◽  
Cast Material ◽  
Guide Vanes ◽  
Significant Difference

Abstract In this paper, AM produced test samples of a IN939 derivative nickel-based alloy were tested for tensile, fatigue and creep properties at temperatures up to 871°C and compared to the traditional cast material. Initial results showed improved tensile and fatigue strength, but a reduction in both long-term creep rupture strength and creep ductility in the AM produced material compared to the cast baseline. Microstructural observations in the AM produced material showed a significant difference in the overall metallurgical characteristics beyond grain size compared to the castings. In addition to the laboratory studies and to provide a direct comparison between AM and traditional castings, both AM and cast components were tested in live engine trials exceeding 4,000 hours. Detailed scanning electron microscopy techniques were used to evaluate the evolution of grain size, gamma-prime, MC carbide and secondary M23C6 carbide size and distribution throughout a 5-step heat treatment process. Post-test evaluations for creep rupture specimens of the AM material showed creep cavitation near grain boundaries. The results from the AM produced material are discussed in comparison to expected properties and characteristics from traditional casting methods. Results have shown that material production and short-term metallurgical properties are sufficient to produce quality high temperature stationary guide vanes, but additional research and development is needed to optimize the AM process to achieve high-temperature creep behavior comparable to castings.

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