scholarly journals Mechanical Behavior of Inconel 625 at Elevated Temperatures

2018 ◽  
Author(s):  
Mauro M. de Oliveira ◽  
Antônio A. Couto ◽  
Gisele F. C. Almeida ◽  
Danieli A. P. Reis ◽  
Nelson B. de Lima ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Aging Effect ◽  
Tensile Tests ◽  
Constant Load ◽  
Anomalous Behavior ◽  
Inconel 625 ◽  
Dynamic Strain ◽  
Intergranular Cracking ◽  
Creep Tests ◽  
Temperature Range

Abstract: The Inconel 625 is a nickel-based alloy has been widely used in the high-temperature application. The Inconel 625 exhibits unstable plastic flow at elevated temperature characterized by serrated yielding, known as Portevin-Le Chatelier effect. The aim of this work is to evaluate the mechanical properties at high temperatures of the Inconel 625. The tensile tests were performed in the temperature range of room temperature until 1000 °C and strain rate of 2x10^-4 to 2x10^-3 s^-1. The creep tests were performed in the temperature range of 600-700 °C, in the stress range of 500-600 MPa in a constant load mode. The surface fracture was observed by optical and scanning electron microscopy. Serrated stress-strain behavior was observed in the curves obtained at 200 to 700 °C, which was associated with the dynamic strain aging effect. The yield strength and the elongation values show an anomalous behavior as a function of the test temperature. An intergranular cracking was observed specimen tensile tested at 500 °C that can be attributed to the decohesion of the carbides along the grain boundaries. The fracture surface of the specimen tensile tested at 700 °C showed the predominance of transgranular cracking with tear dimples with a parabolic shape.

scholarly journals Mechanical Behavior of Inconel 625 at Elevated Temperatures

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 301 ◽  
Author(s):  
Mauro de Oliveira ◽  
Antônio Couto ◽  
Gisele Almeida ◽  
Danieli Reis ◽  
Nelson de Lima ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Aging Effect ◽  
Tensile Tests ◽  
Constant Load ◽  
Anomalous Behavior ◽  
Inconel 625 ◽  
Dynamic Strain ◽  
Intergranular Cracking ◽  
Creep Tests ◽  
Electron Microscopes

Inconel 625 is a nickel-based alloy that is mainly used in high-temperature applications. Inconel 625 exhibits an unstable plastic flow at elevated temperatures characterized by serrated yielding, well-known as the Portevin-Le Chatelier effect. The evaluation of the mechanical properties of Inconel 625 at high temperatures is the aim of this work. The tensile tests were executed in temperatures ranging from room temperature to 1000 °C with strain rates of 2 × 10−4 to 2 × 10−3 s−1. The creep tests were executed in the temperature range of 600–700 °C and in the stress range of 500–600 MPa in a constant load mode. The optical and scanning electron microscopes were used for surface fracture observation. In the curves obtained at 200–700 °C the serrated stress-strain behavior was observed, which was related to the dynamic strain aging effect. The yield strength and the elongation values show anomalous behavior as a function of the test temperature. An intergranular cracking was observed for a specimen tensile tested at 500 °C that can be attributed to the decohesion of the carbides along the grain boundaries. The fracture surface of the specimen tensile tested at 700 °C showed the predominance of transgranular cracking with tear dimples with a parabolic shape.

Tensile and Creep Properties of the Refractory Nb Base In-Situ Composite

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1608-1614
Author(s):  
Jin Hak Kim ◽  
Tatsuo Tabaru ◽  
Hisatoshi Hirai
Keyword(s):  
Fracture Surface ◽  
Tensile Tests ◽  
Constant Load ◽  
Tensile Creep ◽  
Tensile Fracture ◽  
Creep Tests ◽  
Tensile Fracture Surface ◽  
In Situ Composite ◽  
Temperature Ranges

Niobium-base in-situ composite Nb-18Si-5Mo-5Hf-2C (in mol%) was prepared and heat-treated at 2070 K for 20 hour. The uni-axile tensile tests at high temperature ranges and the constant load tensile creep tests at 1570 K were performed. The specimen tensile-tested at 1470 K exhibited the excellent UTS of 450 MPa, and the brittle to ductile transition temperature is between 1470 and 1670 K. The specimens creep tested showed good creep strength; the stress exponent is about 5. The tensile fracture surface of the in-situ composite is complex and attributed to cleavage of the Nb 5 Si 3, Nb ss / Nb 5 Si 3 interface separation, ductile rupture of the Nb ss and correlations of these. On the otherhand, the fracture surface of creep tested consists of intergranular above 150 MPa and transgranular below 120 MPa with severely deformed Nb ss .

Time Dependent Deformation During Indentation Testing

1996 ◽  
Vol 436 ◽  
Author(s):  
B. N. Lucas ◽  
W. C. Oliver ◽  
G. M. Pharr ◽  
J-L. Loubet
Keyword(s):  
Loading Rate ◽  
Time History ◽  
Tensile Tests ◽  
Constant Load ◽  
Indentation Creep ◽  
Creep Tests ◽  
Constant Rate ◽  
Indentation Tests ◽  
Constant Loading Rate ◽  
Indentation Strain

AbstractConstant loading rate/load indentation tests (1/P dP/dt) and constant rate of loading followed by constant load (CRL/Hold) indentation creep tests have been conducted on high purity electropolished indium. It is shown that for a material with a constant hardness as a function of depth, a constant (1/P dP/dt) load-time history results in a constant indentation strain rate (1/h dh/dt). The results of the two types of tests are discussed and compared to data in the literature for constant stress tensile tests. The results from the constant (1/P dP/dt) experiments appear to give the best correlation to steady-state uniaxial data.

scholarly journals Microstructural Evolution of 9CrMoW Weld Metal in a Multiple-Pass Weld

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 847
Author(s):  
Yu-Lun Chuang ◽  
Chu-Chun Wang ◽  
Tai-Cheng Chen ◽  
Ren-Kae Shiue ◽  
Leu-Wen Tsay
Keyword(s):  
Weld Metal ◽  
Elevated Temperatures ◽  
Creep Condition ◽  
Heating System ◽  
Infrared Heating ◽  
Coarse Grained ◽  
Intergranular Cracking ◽  
Creep Failure ◽  
Creep Tests ◽  
Multiple Pass

9CrMoW steel tubes were welded in multiple passes by gas-tungsten arc welding. The reheated microstructures in the Gr. 92 weld metal (WM) of a multiple-pass weld were simulated with an infrared heating system. Simulated specimens after tempering at 760 °C/2 h were subjected to constant load creep tests either at 630 °C/120 MPa or 660 °C/80 MPa. The simulated specimens were designated as the over-tempered (OT, below AC1, i.e., WT-820T) and partially transformed (PT, below AC3, i.e., WT-890T) samples. The transmission electron microscope (TEM) micrographs demonstrated that the tempered WM (WT) displayed coarse martensite packets with carbides along the lath and grain boundaries. Cellular subgrains and coarse carbides were observed in the WT-820T sample. A degraded lath morphology and numerous carbides in various dimensions were found in the WT-890T sample. The grain boundary map showed that the WT-820T sample had the same coarse-grained structure as the WT sample, but the WT-890T sample consisted of refined grains. The WT-890T samples with a fine-grained structure were more prone to creep fracture than the WT and WT-820T samples were. Intergranular cracking was more likely to occur at the corners of the crept samples, which suffered from high strain and stress concentration. As compared to the Gr. 91 steel or Gr. 91 WM, the Gr. 92 WM was more stable in maintaining its original microstructures under the same creep condition. Undegraded microstructures of the Gr. 92 WM strained at elevated temperatures were responsible for its higher resistance to creep failure during the practical service.

Evaluation of Inconel 718 Creep Behavior

2012 ◽  
Vol 326-328 ◽  
pp. 525-529 ◽  
Author(s):  
Karina Martinolli ◽  
Tarcila Sugahara ◽  
Danieli A.P. Reis ◽  
Carlos de Moura Neto ◽  
Ana Cláudia Hirschmann ◽  
...  
Keyword(s):  
Inconel 718 ◽  
Elevated Temperatures ◽  
High Surface ◽  
Constant Load ◽  
Good Resistance ◽  
Creep Tests ◽  
High Mechanical Strength ◽  
Surface Stability ◽  
Aerospace Applications ◽  
Experimental Parameters

Superalloys are used primarily in aerospace applications. These applications require a material with high mechanical strength, good resistance to fatigue and creep, good corrosion resistance and ability to operate continuously at elevated temperatures. These alloys were developed for elevated temperature service, where relatively severe mechanical stressing is encountered, and where high surface stability is frequently required. Inconel 718 has being investigated because it is one of the most widely used superalloys. Constant load creep tests were conducted on a standard creep machine at 600 and 700°C and stress levels of 300 MPa. Sets of curves and experimental parameters for the primary, secondary and tertiary regions, as a function of stress and temperature applied were obtained. The ductility, the creep rate and lifetime was evaluated.

Thermal and Loading Effects on Mechanical Properties of a Hot Isostatically Pressed Si3N4

1994 ◽  
Author(s):  
Jagannathan Sankar ◽  
Jayant Neogi ◽  
Suneeta S. Neogi ◽  
Marvln T. Dixie ◽  
Ranji Vaidyanathan
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Silicon Nitride ◽  
Elevated Temperatures ◽  
Heat Engine ◽  
Tensile Tests ◽  
Tensile Creep ◽  
Uniaxial Tensile ◽  
Creep Tests ◽  
Loading Effects

The effect of thermal soaking on the mechanical properties of a candidate material for advanced heat engine applications namely, hot isostatically pressed (HIPed) silicon nitride (GTEPY6) are reported here. Pure uniaxial tensile tests conducted at room and at elevated temperatures indicated that the tensile strength of this material dropped significantly after 1000°C. The residual tensile strength of PY6 material after thermal soaking at 1200° and 1300°C was also investigated. Test results showed that thermal soaking at 1200° and 1300°C increased the residual tensile strength. The thermal soaking time had a greater effect on the residual tensile strength at 1300°C. Tensile creep tests performed at 1200° and 1300°C showed that the steady state creep rate was influenced by both the temperature and the applied stress. The higher stress exponent in HIPed as compared to a sintered silicon nitride shows higher creep resistance in the case of HIPed materials.

Creep Properties of a High Niobium Containing γ-TiAl Alloy Sheet Material

2002 ◽  
Vol 753 ◽  
Author(s):  
A. Bartels ◽  
S. Bystrzanowski ◽  
R. Gerling ◽  
F.-P. Schimansky ◽  
H. Kestler ◽  
...  
Keyword(s):  
Activation Energy ◽  
Stress Exponent ◽  
Elevated Temperatures ◽  
Sheet Material ◽  
Rolling Direction ◽  
Constant Load ◽  
Alloy Sheet ◽  
Tensile Creep ◽  
Creep Tests ◽  
Fine Grained

ABSTRACTIn this study Ti-46Al-9Nb (at%) sheet material processed by a powder metallurgical route was examined. Subsequent to hot rolling the sheets were subjected to a stress-relief treatment at 1273K for 3 hours. During this heat treatment a fine-grained near gamma microstructure has been formed. 100 hours tensile creep tests under constant load were carried out at 700°C in rolling direction, transverse direction as well as 45° direction. Using the method of load changes a stress exponent of 4.1 was determined. Furthermore, the apparent activation energy was determined in the temperature range of 715 – 775°C. Both stress exponent and activation energy suggest that diffusion assisted dislocation climb is the dominant creep mode. A comparison of these results with those of so-called conventional or so-called “2nd generation” γ-TiAl based alloys, e.g. Ti-46.5Al-4(Cr,Nb,Ta,B) (at%) and Ti-47Al-4(Cr,Mn,Nb,Si,B) (at%), indicates a significantly better creep resistance and a higher activation energy of the high Nb containing alloy. Additionally, internal friction experiments were conducted in order to analyze the deformation behavior under very small strains at elevated temperatures.

Observations on Dynamic Strain Aging Manifestation in Inconel 718 Superalloy

2018 ◽  
Vol 930 ◽  
pp. 390-394 ◽  
Author(s):  
Monica Costa Rezende ◽  
Leonardo Sales Araújo ◽  
Sinara Borborema Gabriel ◽  
Jean Dille ◽  
Luiz Henrique de Almeida
Keyword(s):  
Dynamic Strain Aging ◽  
Inconel 718 ◽  
Strain Aging ◽  
Aging Treatment ◽  
Tensile Tests ◽  
Dynamic Strain ◽  
Dynamic Precipitation ◽  
Intergranular Cracking ◽  
Thermally Activated ◽  
Inconel 718 Superalloy

The manifestation of dynamic strain aging (DSA) in Inconel 718 is reported in this work. Analysis were performed in the material with different microstructures resulting from solution anneal and aging treatment. Tensile tests were made under secondary vacuum with temperature ranging between 200 and 950°C and strain rates of 3.2 x 10-3 to 3.2 x 10-5 s-1. Results showed the range of DSA occurrence. Analysis indicates that at lower temperatures, from approximately 200 to 450°C, serrations are controlled by the diffusion of carbon. At higher temperatures, until 800°C, DSA coincided with the occurrence of other thermally activated phenomena: dynamic precipitation, especially γ’’, and Oxidation Assisted Intergranular Cracking (OAIC). It was observed that competitive phenomena affect DSA manifestation directly due to the availability of niobium in solid solution.

Stress Corrosion Cracking of 13Cr Steels in CO2-H2S-Cl− Environments

CORROSION ◽  
1985 ◽  
Vol 41 (4) ◽  
pp. 211-219 ◽  
Author(s):  
H. Kurahashi ◽  
T. Kurisu ◽  
Y. Sone ◽  
K. Wada ◽  
Y. Nakai
Keyword(s):  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Tensile Tests ◽  
Constant Load ◽  
Corrosion Cracking ◽  
Low Alloy Steels ◽  
Intergranular Cracking ◽  
Cracking Behavior ◽  
Alloy Steels ◽  
Absorption Measurements

Abstract Stress corrosion cracking (SCC) behavior of two 13Cr steels was investigated in aqueous CO2-H2S environments. U-bend tests, constant load tensile tests, and corrosion tests were performed in CO2 environments containing different amounts of H2S. In addition, the slow strain rate tensile (SSRT) tests and hydrogen absorption measurements were done under cathodic hydrogen charging conditions to determine why 13Cr steels are more susceptible to SCC in H2S environments than low alloy steels are. The 13Cr steels were less resistant to SCC in the CO2-H2S environments than low alloy steels were, but some 13Cr steels were not subject to SCC even at a hydrogen sulfide partial pressure of 0.3 atm. Furthermore, it was found that SCC in a CO2-H2S environment was caused by hydrogen embrittlement and that the SCC susceptibility of 13Cr steels was affected by their intergranular cracking behavior. Thus, their microstructures and carbide dispersions are important factors in defining SCC susceptibility of 13Cr steels.

The Effect of Slow-Constant Strain Rates on the Tensile Properties of Selected Alloys at Room and Elevated Temperatures

1974 ◽  
Vol 96 (2) ◽  
pp. 115-122 ◽  
Author(s):  
C. L. Dotson
Keyword(s):  
Strain Rate ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Strength Properties ◽  
Strain Rate Range ◽  
Dynamic Strain ◽  
Strain Rates ◽  
Lower Strain ◽  
Temperature Ranges ◽  
Design Stress

Tensile tests were performed at constant strain rates from 10−2 to 10−5 min−1 on 5454-O and 1100-O aluminum alloys, A515 Grade 70 steel and B166 nickel alloy at room temperature and at elevated-temperature ranges where the design stress basis normally changes from tensile to creep-rupture controlled. The results in general showed that the strength of the alloys decreased at lower strain rates, and the sensitivity to strain rate was greater at elevated temperatures except where metallurgical phenomena such as dynamic strain aging negate the effects of strain rate. At the highest temperature the decrease in strength properties ranged from 11 to 50 percent over the strain rate range for different alloys.

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