Fracture Toughness Properties of a Modern Ni-Mo-Cr High Temperature Alloy

2000 ◽  
Author(s):  
R. R. Seeley ◽  
D. L. Klarstrom
Keyword(s):  
Fracture Toughness ◽  
Impact Toughness ◽  
Tensile Ductility ◽  
Charpy Impact ◽  
Thermal Exposure ◽  
Strong Relationship ◽  
Fracture Toughness Test ◽  
Temperature Fracture ◽  
Nickel Base

The Ni-Mo-Cr alloy (HAYNES® 242™) is an age-hardenable alloy that can be significantly strengthened by a simple aging heat treatment at 650°C (1200°F). Long-term thermal exposures at moderate temperatures increase the strength and decrease the ductility and Charpy V-notch impact toughness. Tensile ductility and Charpy impact toughness have traditionally been used to study the effect of long-term thermal exposure on mechanical properties. However, there has been little or no work reported on the effect of long-term thermal exposures on the fracture toughness of nickel-base alloys. The room temperature fracture toughness (KJc) properties have been evaluated for Ni-Mo-Cr plate material in the annealed, annealed and aged, and annealed plus long-term thermal exposed condition. The microstructural and fracture mode characteristics of this alloy were examined as well. The tensile ductility, impact toughness and fracture conditions of the toughness properties were decreased by a long-term thermal exposure at 650°C (1200°F). The fracture toughness test data revealed the crack extension during the KJc tests to be stable throughout the test. The mechanical property data suggest a strong relationship between fracture toughness and tensile ductility. The microstructures and fracture surface morphologies for three metallurgical conditions of the Ni-Mo-Cr alloy are presented.

Impact toughness of a modified HR3C austenitic steel after long-term thermal exposure at 650 °C

2019 ◽  
Vol 740-741 ◽  
pp. 71-81 ◽  
Author(s):  
C.Z. Zhu ◽  
Y. Yuan ◽  
J.M. Bai ◽  
P. Zhang ◽  
J.B. Yan ◽  
...  
Keyword(s):  
Impact Toughness ◽  
Austenitic Steel ◽  
Thermal Exposure

Mechanical Properties of SA508 Gr.4N Model Alloys as a High Strength RPV Steel

2010 ◽  
Author(s):  
Min-Chul Kim ◽  
Ki-Hyoung Lee ◽  
Bong-Sang Lee ◽  
Whung-Whoe Kim
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Impact Toughness ◽  
Power Plants ◽  
Charpy Impact ◽  
Alloying Elements ◽  
Low Alloy Steels ◽  
Charpy Impact Toughness ◽  
Age Related ◽  
Alloy Steels

Demands of RPV materials with higher strength and toughness are rising to increase the power capacity and the operation life of nuclear power plants. The ASME SA508 Gr.4N specification can give a superior toughness and strength to the commercial low alloy steels such as SA508 Gr.3. However, the SA508-Gr.4N steels have not yet been used commercially due to a lack of information of the productivity and the age related properties. While the irradiation embrittlement studies are going-on, the current paper focused on the effects of alloying elements such as Ni, Cr and Mo on the fracture mechanical properties of the SA508 Gr.4N low alloy steels. Various model alloys were fabricated by changing the contents of alloying elements based on the composition range of the ASME specification. Tensile properties, Charpy impact toughness and fracture toughness of the model alloys were evaluated and those properties were discussed with the microstructural characteristics of each alloy. The strengths of the alloys were increased with increase of the Ni and Mo contents while there was no remarkable change of the yield strength with the Cr addition. The Charpy impact and fracture toughness were considerably improved with the increase of Ni, Cr contents. The Mo addition did not change the toughness properties significantly. The Cr contents were more effective on the fracture toughness through changing the carbides precipitation characteristics and the Ni contents were effective on the Charpy impact toughness through changing the effective grain size.

The Microstructure Evolution of a Nickel-Base Single Crystal Superalloy after Long-Term Aging

2015 ◽  
Vol 1088 ◽  
pp. 217-220 ◽  
Author(s):  
Yu Xian Jia
Keyword(s):  
Single Crystal ◽  
Exposure Time ◽  
Microstructure Evolution ◽  
Ageing Time ◽  
Thermal Exposure ◽  
Single Crystal Superalloy ◽  
Phase Precipitation ◽  
Tcp Phase ◽  
Nickel Base

Microstructure evolution of a nickel-base single crystal superalloy during thermal exposure at 982°C was investigated. The SEM studies revealed that the size of γ' phase increased and some of which linked together with the elongation of the exposure time. There is acicular phase precipitation after the long-term ageing treatment. The TCP phase is not increased by the increment of ageing time after reaching a certain amount. There are skeleton shape carbides precipitate after 100h and 300h. The amount of precipitated carbides decreases by the elongation of ageing time.

Crack Arrest Test Results of Unirradiated and Irradiated German RPV Steels

2013 ◽  
Author(s):  
Florian Obermeier ◽  
Julia Barthelmes ◽  
Elisabeth Keim ◽  
Hieronymus Hein ◽  
Hilmar Schnabel ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Lower Bound ◽  
Pressure Vessel ◽  
Charpy Impact ◽  
Crack Arrest ◽  
Reactor Pressure Vessel ◽  
Test Method ◽  
Fracture Toughness Test ◽  
Test Results ◽  
Reactor Pressure

In the CARISMA[1] and CARINA[2] projects comprehensive tensile, Charpy-impact and fracture toughness tests were performed for unirradiated and irradiated original reactor pressure vessel (RPV) steel specimens from German pressurized water reactors (PWR) up to neutron fluences in the range of 60 operational years and beyond. In addition, crack arrest fracture toughness tests were performed to demonstrate the crack arrest behavior of the materials. To determine the crack arrest properties of ferritic steels, the designated test method according to ASTM E1221 [3] was used. However, in particular for irradiated reactor pressure vessel materials with higher irradiation embrittlement, the prescribed standard test specimen does not always provide adequate test results. During starter notch preparation annealing effects occurred in the heat affected zone (HAZ) of the brittle weld of the starter notch causing crack arrest in the HAZ after unstable crack initiation. Therefore a modified test method to perform crack arrest tests with so called duplex specimens was investigated. In this paper this modified method and the test results of five base and four weld metals with a fluence up to 4,69E+19 cm−2 (E >1 MeV) are discussed. The available test results show that the duplex specimen is an appropriate alternative to the standard compact crack arrest (CCA) specimen. The measured KIa fracture toughness data are enveloped by the “lower bound” of the ASME KIa-curve indexed with RTNDTj or TKIa but not all data are enveloped by indexing the “lower bound” curve with RTT0 like described in the ASME Code Case N-629 [4]. Furthermore correlations of the crack arrest test results with Charpy-impact and fracture toughness test results will be shown.

Coarsening Behavior of Precipitates in a Conventional Cast Nickel Base Superalloy during Long Term Thermal Exposure

2014 ◽  
Vol 788 ◽  
pp. 452-458
Author(s):  
Qiang Zeng ◽  
Ping Yan ◽  
Jing Chen Zhao ◽  
Long Fei Zhang ◽  
Lian Li
Keyword(s):  
Aging Time ◽  
Early Stage ◽  
Aging Treatment ◽  
Thermal Exposure ◽  
Nickel Base Superalloy ◽  
Coarsening Behavior ◽  
Nickel Base ◽  
The One ◽  
Base Superalloy

A long term aging treatment at 900oC for 3000h was carried out on a conventional cast nickel base superalloy with standard solution and aging treatment. The microstructural evolution including the phases within grains and at grain boundaries (GBs) during thermal exposure in the alloy was observed using OM and SEM. It was shown that the major phases in the alloy after standard heat treatment were γ' precipitates and coarse blocky MC carbides, both of which were distributed not only within grains but also at GBs. During aging, the size of MC carbides and γ' precipitates both within grains and at GBs increased with increasing aging time. It was found that two characteristics of MC carbide and γ' precipitates evolved with aging time: the one is that the coarsening ratio of carbides and γ' precipitates at GBs were significantly higher than that of carbide and γ' precipitates inside the grains; the other is that the coarsening ratio of carbides was markedly higher than that of γ' precipitates. M6C carbide and η phase initially formed in the edge of MC carbide at the expense of MC carbides and γ' precipitates in the vicinity of MC during the early stage of aging. After 3000h, MC carbides inside the grains were covered by η phase films, while those distributed at GBs were completely decomposed into η phase and M6C particles.

Processing and Mechanical Properties of RuAl-Based Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1469-1474 ◽  
Author(s):  
T.D. Reynolds ◽  
M. Acosta ◽  
David R. Johnson
Keyword(s):  
Fracture Toughness ◽  
Cyclic Oxidation ◽  
Room Temperature ◽  
Single Phase ◽  
Tensile Ductility ◽  
Tensile Behavior ◽  
Directionally Solidified ◽  
Two Phase ◽  
Heat Treated ◽  
Temperature Fracture

Alloys of Ru-Al-Cr with compositions between Ru-10Al-35Cr and Ru-3Al-39Cr (at.%) were directionally solidified and heat treated to produce single phase hcp-Ru(Cr,Al) and two phase B2-hcp microstructures. The room temperature fracture toughness, tensile behavior, and cyclic oxidation behavior at 1100°C were investigated and compared to previous results measured from RuAl and Ru-Al-Mo alloys. For microstructures consisting of a Ru(Cr,Al) matrix with fine RuAl precipitate, a good room temperature fracture toughness, tensile ductility, and oxidation resistance at 1100°C were measured.

Topological phase inversion after long-term thermal exposure of nickel-base superalloys: Experiment and phase-field simulation

2017 ◽  
Vol 124 ◽  
pp. 151-158 ◽  
Author(s):  
J.V. Goerler ◽  
I. Lopez-Galilea ◽  
L. Mujica Roncery ◽  
O. Shchyglo ◽  
W. Theisen ◽  
...  
Keyword(s):  
Phase Field ◽  
Phase Inversion ◽  
Thermal Exposure ◽  
Topological Phase ◽  
Phase Field Simulation ◽  
Field Simulation ◽  
Nickel Base Superalloys ◽  
Nickel Base

Effects of Ruthenium on Microstructure and Stress Rupture Properties of a Nickel-Base Single Crystal Superalloy

2013 ◽  
Vol 747-748 ◽  
pp. 777-782
Author(s):  
Shuai Yang ◽  
Jian Zhang ◽  
Yu Shi Luo ◽  
Yun Song Zhao ◽  
Ding Zhong Tang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Stress Rupture ◽  
Thermal Exposure ◽  
Microstructural Stability ◽  
Stress Rupture Properties ◽  
Tcp Phases ◽  
Mean Size ◽  
Nickel Base ◽  
Rupture Properties

The effect of Ru addition (0 wt.%, 3 wt.%, 5 wt.%), on γ morphology, elemental segregation, microstructural stability under long-term thermal exposure at 980 and stress rupture properties at 1100°C/130MPa have been studied. The results showed that with the increase of Ru content, the γ/γ eutectic volume fraction and the dendrite arm spacing decreased gradually. The γ' phase mean size in three alloys decreased with the increase of the Ru content. On the other hand, the dendrite segregation of Al, Ta towards interdendrite area and ReW towards dendrite core area was alleviated gradually with the increase of the Ru content. The increase of Ru content from 0 wt.% to 5 wt.% pronouncedly enhanced the stress rupture properties by suppressing the precipitation of TCP phases effectively at high temperature.

Fracture Toughness and Charpy Impact Test of MIM Steels and Correlation of Results by KIC- CVN Relationships

2019 ◽  
Vol 810 ◽  
pp. 1-6
Author(s):  
Radek Tomášek ◽  
Vratislav Mareš ◽  
Lukáš Horsák
Keyword(s):  
Fracture Toughness ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Impact Testing ◽  
Test Method ◽  
Transition Curve ◽  
Fracture Toughness Test ◽  
Average Deviation ◽  
Charpy Impact Testing ◽  
Shelf Region

This paper presents results of fracture toughness and Charpy impact tests of 4 steels prepared by metal injection moulding (MIM) method: AISI 4140, 4605, 17-4 PH and SS 420W Grade. Charpy impact testing was performed on the series of machined specimens with sub-size cross-section to obtain values of CVN impact energy. Fracture toughness test method according to ASTM E1820 was performed on SENB specimens, fatigue pre-cracked, to obtain values of KIC. All tests were performed at the room temperature. After the material testing, next step was to evaluate the results and apply known correlation relationships between fracture toughness KIC and Charpy impact CVN energies. Many empirical relations exist and describe existence of such relationship. Procedure was used to correlate energies of sub-size Charpy specimens to full-size specimens. Several proposed correlation relationships from transition and upper shelf region of transition curve were used, where the best correlation was found to be Robert-Newtons with average deviation of 22% in comparison to tested values.

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