Biaxial Thermal Creep of Alloy 617 and Alloy 230 for VHTR Applications

2014 ◽  
Author(s):  
Kun Mo ◽  
Wei Lv ◽  
Hsiao-Ming Tung ◽  
Di Yun ◽  
Yinbin Miao ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Creep ◽  
Secondary Creep ◽  
Alloy 617 ◽  
Creep Equation ◽  
Creep Stress ◽  
High Temperature Mechanical Properties ◽  
Inconel 617 ◽  
Creep Regime ◽  
Secondary Regime

In this study, we employed pressurized creep tubes to investigate the biaxial thermal creep behavior of Inconel 617 (Alloy 617) and Haynes 230 (Alloy 230). Both alloys have been considered to be the primary candidate structural materials for very high temperature reactors (VHTRs) due to their exceptional high-temperature mechanical properties. The current creep experiments were conducted at 900°C for the effective stress range of 15–35 MPa. For both alloys, complete creep strain development with primary, secondary, and tertiary regimes were observed in all studied conditions. The tertiary creep was found to be dominant in the entire creep lives of both alloys. With increasing applied creep stress, the fraction of the secondary creep regime decreases. The nucleation, diffusion, and coarsening of creep voids and carbides on grain boundaries was found to be the main reason for the limited secondary regime, and was also found to be the major cause of creep fracture. The creep curves computed using the adjusted creep equation of the form ε = Aσ cosh−1(1 + rt) + Pσntm agree well with the experimental results for both alloys at the temperatures of 850–950°C. Paper published with permission.

Biaxial Thermal Creep of Alloy 617 and Alloy 230 for VHTR Applications

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Kun Mo ◽  
Wei Lv ◽  
Hsiao-Ming Tung ◽  
Di Yun ◽  
Yinbin Miao ◽  
...  
Keyword(s):  
High Temperature ◽  
Thermal Creep ◽  
Secondary Creep ◽  
Alloy 617 ◽  
Creep Equation ◽  
Creep Stress ◽  
High Temperature Mechanical Properties ◽  
Inconel 617 ◽  
Creep Regime ◽  
Secondary Regime

In this study, we employed pressurized creep tubes to investigate the biaxial thermal creep behavior of Inconel 617 (alloy 617) and Haynes 230 (alloy 230). Both alloys are considered to be the primary candidate structural materials for very high-temperature reactors (VHTRs) due to their exceptional high-temperature mechanical properties. The current creep experiments were conducted at 900 °C for the effective stress range of 15–35 MPa. For both alloys, complete creep strain development with primary, secondary, and tertiary regimes was observed in all the studied conditions. Tertiary creep was found to be dominant over the entire creep lives of both alloys. With increasing applied creep stress, the fraction of the secondary creep regime decreases. The nucleation, diffusion, and coarsening of creep voids and carbides on grain boundaries were found to be the main reasons for the limited secondary regime and were also found to be the major causes of creep fracture. The creep curves computed using the adjusted creep equation of the form ε=Aσcosh−1(1+rt)+Pσntm agree well with the experimental results for both alloys at the temperatures of 850–950 °C.

Microstructure and High Temperature Mechanical Properties of Inconel 617

2007 ◽  
Vol 544-545 ◽  
pp. 411-414 ◽  
Author(s):  
Tae Sun Jo ◽  
Gil Su Kim ◽  
Young Ik Seo ◽  
Woo Seog Ryu ◽  
Young Do Kim
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Oxide Layer ◽  
Tube Material ◽  
Internal Oxide ◽  
High Temperature Mechanical Properties ◽  
Microstructure And Mechanical Properties ◽  
Inconel 617 ◽  
Second Phases ◽  
High Temperature Gas

Inconel 617 is a candidate tube material for high temperature gas-cooled reactors (HTGR). The microstructure and mechanical properties of Inconel 617 were studied after exposure at high temperature of 1050oC. The dominant oxide layer was Cr-oxide. The internal oxide and Crdepleted region were observed below the Cr-oxide layer. The major second phases are M23C6 and M6C types of carbides. The composition of M23C6 and M6C were determined to be Cr21Mo2C6 and Mo3Cr2(Ni,Co)1C, respectively, by EDS. These carbides are coarsened during exposure. M6C carbide is more stable than M23C6 at high temperature. There was not much change in mechanical properties after exposure at 1050oC for 1000 h.

High Temperature Properties of Ti3SiC2-SiC Composites

2010 ◽  
Vol 105-106 ◽  
pp. 222-225
Author(s):  
De Gui Zhu ◽  
Hui Yi Tang ◽  
Hong Liang Sun ◽  
Shuang Quan Guo
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Composite Materials ◽  
Hot Isostatic Pressing ◽  
In Situ Synthesis ◽  
Secondary Creep ◽  
High Tensile Strength ◽  
Sic Composites ◽  
Creep Regime

Fully dense Ti3SiC2-64vol.%SiC(0.5m) composite materials are successfully fabricated by in situ synthesis under hot isostatic pressing. The high temperature flexure, tension and creep of Ti3SiC2-SiC composites were studied, and the results indicated that the composite had a high tensile strength under high temperature. Above 1000°C the composite were displayed a good high temperature plastic. The creep behavior is characterized by two regimes: an initial transient regime, where έ(dε/dt) decreases with t (time); a secondary creep regime in which έ is more or less constant with time.

scholarly journals Low Cycle Fatigue Behaviors of Alloy 617 (INCONEL 617) Weldments for High Temperature Applications

Metals ◽  
2016 ◽  
Vol 6 (5) ◽  
pp. 100 ◽  
Author(s):  
Rando Dewa ◽  
Seon Kim ◽  
Woo Kim ◽  
Eung Kim
Keyword(s):  
High Temperature ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Alloy 617 ◽  
Inconel 617 ◽  
Temperature Applications

Positive Effects of High-Temperature Steel Creep Behavior on Continuous Casting Slab

2016 ◽  
Vol 723 ◽  
pp. 103-110
Author(s):  
Long Guo ◽  
Xing Zhong Zhang
Keyword(s):  
High Temperature ◽  
Continuous Casting ◽  
Creep Behavior ◽  
Casting Machine ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Secondary Creep ◽  
Creep Equation ◽  
Positive Effects ◽  
Continuous Casting Slab

Mechanical properties and creep behavior of continuous casting slab subjected to uniaxial tensile tests at 1100 and 1150 °C were considered in this paper. All of specimens was given a typical in-situ melting thermal history and interrupted cooling cycle before testing. An increase in load and temperature accelerates the creep rate thereby decreasing the steady state range. A new creep equation whose parameters are calculated by inverse-estimation using the regression analysis was proposed based on Norton-Bailey creep law. Primary and secondary creep stages could be described accurately by the new equation. Positive creep effects on straightening technology in continuous casting slab were presented in this paper. Involute continuous straightening technology could give full play to the role of steel creep deformation at high temperature. This research is helpful for the design of the new casting machine and improvement of old casting machine in using depended on high temperature creep behavior.

Origin and Effect of Back Stress on Cyclic Creep Deformation of 316H Stainless Steel

2015 ◽  
Author(s):  
Abdullah Al Mamun ◽  
Richard James Moat ◽  
P. John Bouchard
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Creep Deformation ◽  
Deformation Rate ◽  
Cyclic Creep ◽  
Back Stress ◽  
Secondary Creep ◽  
Creep Equation ◽  
Simplified Approach ◽  
Power Law Creep

Components in power generation plants operate at high temperature and often go through complex cyclic loading sequence during its operations. ‘Back stress’ is generated during such cyclic loading due to inhomogeneity in deformation at micro scale and significantly affects the overall creep lifetime of the materials of these components. Using a time of flight neutron diffraction facility, we studied the origin of back stress and its effects on creep deformation rate of AISI type 316H austenitic steel during cyclic creep at 650 °C. The result shows, during high temperature cyclic loading of this material for any given level of stress, the magnitude of back stress vary significantly depending on the point in the cycle being observed. The effective back stress levels associated with dwells introduced at different points in the cycle shows good co-relation with the measured macroscopic secondary creep deformation rate. Moreover, a simplified approach using modified power law creep equation is proposed to quantify back stress from a known creep deformation rate.

TEM Studies of Grain Boundary Films in Si3N4 Ceramics

1991 ◽  
Vol 49 ◽  
pp. 930-931
Author(s):  
H.-J. Kleebe ◽  
J.S. Vetrano ◽  
J. Bruley ◽  
M. Rühle
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Hot Isostatic Pressing ◽  
Amorphous Film ◽  
Liquid Phase Sintering ◽  
Second Phase ◽  
High Temperature Mechanical Properties ◽  
Triple Points ◽  
Boundary Films

It is expected that silicon nitride based ceramics will be used as high-temperature structural components. Though much progress has been made in both processing techniques and microstructural control, the mechanical properties required have not yet been achieved. It is thought that the high-temperature mechanical properties of Si3N4 are limited largely by the secondary glassy phases present at triple points. These are due to various oxide additives used to promote liquid-phase sintering. Therefore, many attempts have been performed to crystallize these second phase glassy pockets in order to improve high temperature properties. In addition to the glassy or crystallized second phases at triple points a thin amorphous film exists at two-grain junctions. This thin film is found even in silicon nitride formed by hot isostatic pressing (HIPing) without additives. It has been proposed by Clarke that an amorphous film can exist at two-grain junctions with an equilibrium thickness.

Precipitate coarsening during hot-compression testing of NiAl + 2 at.% Nb

1986 ◽  
Vol 44 ◽  
pp. 598-599
Author(s):  
W. M. Sherman ◽  
K. M. Vedula
Keyword(s):  
High Temperature ◽  
Flow Stress ◽  
Weight Ratio ◽  
Constant Strain Rate ◽  
Hot Compression ◽  
Compression Testing ◽  
Second Phase ◽  
Precipitate Coarsening ◽  
High Temperature Mechanical Properties ◽  
Ordered Intermetallic

The strength to weight ratio and oxidation resistance of NiAl make this ordered intermetallic, with some modifications, an attractive candidate to compete with many superalloys for high temperature applications. Recent studies have shown that the inherent brittleness of many polycrystalline intermetallics can be overcome by micro and macroalloying. It has also been found that the high temperature mechanical properties of NiAl can be enhanced through the addition of Nb by powder metallurgical techniques forming a dispersed second phase through interdiffusion in a polycrystalline matrix. A drop in the flow stress is observed however in a NiAl-2 at.% Nb alloy after 0.2 % strain during constant strain rate hot compression testing at 1025°C. The object of this investigation was to identify the second phase and to determine the cause of the flow stress drop.

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