Effect of Temperature and Specimen Thickness on Toughness of Nickel Alloy 22

2007 ◽  
Vol 345-346 ◽  
pp. 529-532
Author(s):  
John F. Grubb ◽  
Michael P. Manahan Sr.
Keyword(s):  
Nickel Alloy ◽  
Impact Test ◽  
Spent Nuclear Fuel ◽  
High Energy ◽  
Effect Of Temperature ◽  
Specimen Thickness ◽  
Test Machine ◽  
Energy Capacity ◽  
Full Size ◽  
Alloy 22

Nickel Alloy 22, UNS N06022, is being evaluated for use as the material of construction in permanent containers for spent nuclear fuel in Yucca Mountain, NV. To meet nuclear design criteria, Charpy impact data were required for the N06022 plate material, but conventional full-size specimens exceed the energy capacity of typical 400 J impact test machines, which results in stopping the pendulum during the test. Half-size specimens break with about 40% of the machine energy capacity, but their use raises questions concerning energy scaling to full size equivalent data. To address this, a range of subsize specimens were tested at room temperature using a standard 400 J impact test machine, and full-size, 3/4-size, and 2/3-size specimens were tested on a high energy capacity, 950J machine. Additional tests were performed at temperatures ranging from -196 to +200°C. Impact energy and lateral expansion measurements for the various test conditions are presented, their implications are examined, and a new model for absorbed energy correlation between subsize specimens and full size conventional Charpy specimens is proposed.

Overview of NIST Activities on Sub-Size and Miniaturized Charpy Specimens: Correlations With Full-Size Specimens and Verification Specimens for Small-Scale Pendulum Machines

2015 ◽  
Author(s):  
Enrico Lucon ◽  
Chris N. McCowan ◽  
Raymond L. Santoyo
Keyword(s):  
Impact Test ◽  
Energy Levels ◽  
High Energy ◽  
Maximum Force ◽  
Small Scale ◽  
Test Results ◽  
Absorbed Energy ◽  
Line Pipe ◽  
Full Size ◽  
Alloy Steels

NIST in Boulder Colorado investigated the correlations between impact test results obtained from standard, full-size Charpy specimens (CVN) and specimens with reduced thickness (sub-size Charpy specimens, SCVN) or reduced or scaled cross-section dimensions (miniaturized Charpy specimens, MCVN). A database of instrumented impact test results was generated from four line pipe steels, two quenched and tempered alloy steels, and an 18 Ni maraging steel. Correlations between specimen types were established and compared with previously published relationships, considering absorbed energy, ductile-to-brittle transition temperature, and upper shelf energy. Acceptable correlations were found for the different parameters, even though the uncertainty of predictions appears exacerbated by the expected significant experimental scatter. Furthermore, we report on the development of MCVN specimens for the indirect verification of small-scale pendulum machines (with potential energies between 15 J and 50 J), which cannot be verified with full-size verification specimens. Small-scale pendulum machines can now be verified at room temperature with certified reference specimens of KLST type (3 mm × 4 mm × 27 mm), supplied by NIST at three certified absorbed energy levels (low energy, 1.59 J; high-energy, 5.64 J; super-high energy, 10.05 J). These specimens can also be used to verify the performance of instrumented Charpy strikers through certified maximum force values. Certified reference values for both absorbed energy and maximum force were established by means of an interlaboratory comparison (Round-Robin), which involved nine qualified and experienced international laboratories.

scholarly journals Impact Testing of Stainless Steel Materials

2005 ◽  
Author(s):  
R. K. Blandford ◽  
D. K. Morton ◽  
T. E. Rahl ◽  
S. D. Snow
Keyword(s):  
Stainless Steel ◽  
Strain Rate ◽  
Impact Test ◽  
Spent Nuclear Fuel ◽  
Impact Testing ◽  
Radioactive Material ◽  
Test Machine ◽  
Strain Rates ◽  
Stress Strain ◽  
The Impact

Stainless steels are used for the construction of numerous spent nuclear fuel or radioactive material containers that may be subjected to high strains and moderate strain rates (10 to 200 per second) during accidental drop events. Mechanical characteristics of these materials under dynamic (impact) loads in the strain rate range of concern are not well documented. The goal of the work presented in this paper was to improve understanding of moderate strain rate phenomena on these materials. Utilizing a drop-weight impact test machine and relatively large test specimens (1/2-inch thick), initial test efforts focused on the tensile behavior of specific stainless steel materials during impact loading. Impact tests of 304L and 316L stainless steel test specimens at two different strain rates, 25 per second (304L and 316L material) and 50 per second (304L material) were performed for comparison to their quasi-static tensile test properties. Elevated strain rate stress-strain curves for the two materials were determined using the impact test machine and a “total impact energy” approach. This approach considered the deformation energy required to strain the specimens at a given strain rate. The material data developed was then utilized in analytical simulations to validate the final elevated stress-strain curves. The procedures used during testing and the results obtained are described in this paper.

Overview of NIST Activities on Subsize and Miniaturized Charpy Specimens: Correlations With Full-Size Specimens and Verification Specimens for Small-Scale Pendulum Machines

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Enrico Lucon ◽  
Chris N. McCowan ◽  
Raymond L. Santoyo
Keyword(s):  
Energy Use ◽  
Impact Test ◽  
High Energy ◽  
Maximum Force ◽  
Small Scale ◽  
Test Results ◽  
Line Pipe ◽  
Full Size ◽  
Alloy Steels ◽  
Reference Specimens

NIST in Boulder, CO investigated the correlations between impact test results obtained from standard, full-size Charpy V-notch (CVN) specimens and specimens with reduced thickness (subsize Charpy V-notch specimens (SCVN)) or reduced or scaled cross section dimensions (miniaturized Charpy V-notch specimens (MCVN)). A database of instrumented impact test results was generated from four line pipe steels: two quenched alloy steels, a tempered alloy steel, and a 18 Ni maraging steel. Correlations between specimen types were established and compared with the previously published relationships, considering absorbed energy (KV), ductile-to-brittle transition temperature (DBTT), and upper shelf energy (USE). Acceptable correlations were found for the different parameters, even though the uncertainty of predictions appears exacerbated by the expected significant experimental scatter. Furthermore, we report on the development of MCVN specimens for the indirect verification of small-scale pendulum machines (with potential energies between 15 J and 50 J), which cannot be verified with full-size verification specimens. Small-scale pendulum machines can now be verified at room temperature with certified reference specimens of KLST type (3 mm × 4 mm × 27 mm), supplied by NIST at three certified KV levels (low energy (LL), 1.59 J; high energy (HH), 5.64 J; and super-high (SH) energy, 10.05 J). These specimens can also be used to verify the performance of instrumented Charpy strikers through certified maximum force values. Certified reference values for both KV and maximum force were established by means of an interlaboratory comparison (Round-Robin), which involved nine qualified and experienced international laboratories.

The effect of temperature on high-resolution TEM image contrast

1995 ◽  
Vol 53 ◽  
pp. 640-641
Author(s):  
T. Geipel ◽  
W. Mader ◽  
P. Pirouz
Keyword(s):  
Form Factor ◽  
Inelastic Scattering ◽  
Accurate Method ◽  
Waller Factor ◽  
Effect Of Temperature ◽  
Specimen Thickness ◽  
Influence Of Temperature ◽  
Debye Waller Factor ◽  
Influence Of Temperature On ◽  
Atomic Form Factor

Temperature affects both elastic and inelastic scattering of electrons in a crystal. The Debye-Waller factor, B, describes the influence of temperature on the elastic scattering of electrons, whereas the imaginary part of the (complex) atomic form factor, fc = fr + ifi, describes the influence of temperature on the inelastic scattering of electrons (i.e. absorption). In HRTEM simulations, two possible ways to include absorption are: (i) an approximate method in which absorption is described by a phenomenological constant, μ, i.e. fi; - μfr, with the real part of the atomic form factor, fr, obtained from Hartree-Fock calculations, (ii) a more accurate method in which the absorptive components, fi of the atomic form factor are explicitly calculated. In this contribution, the inclusion of both the Debye-Waller factor and absorption on HRTEM images of a (Oll)-oriented GaAs crystal are presented (using the EMS software.Fig. 1 shows the the amplitudes and phases of the dominant 111 beams as a function of the specimen thickness, t, for the cases when μ = 0 (i.e. no absorption, solid line) and μ = 0.1 (with absorption, dashed line).

Experimental Determination of Dynamic Characteristics of a Full Size Gas Turbine Tilting-Pad Journal Bearing by an Impact Test Method

1991 ◽  
Author(s):  
S. H. Chan ◽  
M. F. White
Keyword(s):  
Gas Turbine ◽  
Impact Test ◽  
Journal Bearing ◽  
Estimation Procedure ◽  
Response Spectra ◽  
Test Method ◽  
Full Size ◽  
Tilting Pad ◽  
Tilting Pad Journal Bearing ◽  
The Impact

Abstract Measurements have been taken on an experimental rotor-bearing test rig which consists of a full size gas turbine shaft supported by two five-pad tilting-pad journal bearings. The impact test method was applied by exciting one end of the shaft in-situ by means of a hammer blow. Impact forces and response displacements were collected and analysed with suitable corrections for runout effect. Averaged frequency response spectra thus obtained were used in a parameter estimation procedure to calculate the dynamic coefficients of the tested tilting-pad journal bearing. An analytical single degree-of-freedom model was employed and one of the input parameters in the mechanical model, the effective mass, was found to significantly influence the estimated results. The measured stiffness and damping coefficients are compared with results predicted by a bearing design program. Possible sources of discrepancies between experimental and theoretical results are discussed.

Characterization of Melting and Solidification Phenomena in Electromagnetic Punching of Aluminum Tubes

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
De Waele Wim ◽  
Faes Koen ◽  
Van Haver Wim
Keyword(s):  
Plastic Deformation ◽  
Energy Levels ◽  
High Energy ◽  
Effect Of Temperature ◽  
Fracture Mechanisms ◽  
Time Interval ◽  
Short Time Interval ◽  
Total Width ◽  
Premature Failure ◽  
Charging Energy

Electromagnetic punching of tubular products is considered to be a promising innovative perforating process. The required punching energy decreases when using high velocities. Also, less tools are required when compared to conventional mechanical punching. However, the increase in punching speed can involve new strain and fracture mechanisms which are characteristic of the dynamic loading. In high energy rate forming processes the effect of temperature versus time gradient on the material properties becomes important due to the heat accumulated from plastic deformation and friction. The deformation induced heating will promote strain localization in it, possibly degrade its formability and cause premature failure in the regions of high localized strain. The feasibility of the electromagnetic pulse forming process for punching holes in aluminum cylindrical specimens has been investigated on an experimental trial-and-error basis. Experiments were performed using a Pulsar system (model 50/25) with a maximum charging energy of 50 kJ and a discharge circuit frequency of 14 kHz. Microscopic and metallographic inspection of the punched workpieces, together with hardness measurements, was performed to critically evaluate the quality of the cuts. It was observed that damage occurred at part of the edge of the punched hole during some of the perforation experiments. It was evidenced that in most workpieces, especially those performed at higher charging energy levels, a considerably high temperature must have been reached in the regions near the punched hole. The aluminum in this region was assumed to have melted and resolidified. These assumptions were affirmed by the following observations. Microscopic-size precipitates present in the unaffected base metal microstructure, had completely dissolved in that region; shrinkage cavities and dendrite rich regions were clearly visible. Next to this region, a heat affected zone was present where the grain boundaries had partially melted and precipitates partially disappeared. Considerably high temperatures, in the order of 520 to 660 °C, were reached in the regions around the punched holes, leading to melting and resolidification of the material. The total width of the thermally affected regions appeared to be larger at higher energy levels. The combination of heat generated by ohmic heating and by plastic deformation in a very short time interval is the most probable cause of the high peak temperatures that have occurred during the electromagnetic punching process.

Effect of Temperature on the Evolved Microstructure During Laser Beam Forming of Sheet Steels

2017 ◽  
Author(s):  
Stephen Akinlabi ◽  
Madindwa Mashinini ◽  
Esther Akinlabi
Keyword(s):  
High Temperature ◽  
Energy Density ◽  
Laser Beam ◽  
Laser Energy ◽  
High Energy ◽  
Phase Changes ◽  
High Energy Density ◽  
Effect Of Temperature ◽  
Beam Forming ◽  
Heating And Cooling

Laser Beam Forming (LBF) being a novel technique and non-contact manufacturing process, employs laser beam as the tool of shaping and bending metal sheets into different shapes and curvatures for various applications. LBF is a high-temperature process, where rapid heating and cooling occurs causing microstructural changes like dynamic recrystallization and phase changes. The study becomes necessary to ensure that the structural integrity of the processed material is not compromised. Hence, the investigation focuses on the effect of temperature on the developed microstructure during the LBF process. The design of experiment was considered, using three levels and five factors. The experimentally measured curvatures were validated with the predicted measured curvatures, which were found to be in agreement. The result shows that the developed ferrite and pearlite grains were due to the heating and cooling. Furthermore, the average grain sizes at a low energy density of about 355°C and high energy density of about 747°C were found to be about 10 μm and 6 μm respectively. It is implied that the high temperature from the high laser energy aided the deformation of the grains significantly. However, such high temperature must be closely monitored so to avoid metallurgical notches in the processed component.

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