Ronald Ballinger - Academia.edu (original) (raw)

Papers by Ronald Ballinger

Advances in Cryogenic Engineering Materials, 1996

ABSTRACT

International Heat Treatment and Surface Engineering, 2010

ABSTRACT

AIP Conference Proceedings, 2006

ABSTRACT

Journal of electron microscopy technique, 1989

In this paper, we present a technique for analysis of composition gradients, using an analytical ... more In this paper, we present a technique for analysis of composition gradients, using an analytical electron microscope, within the primary phase of a two-phase alloy for the case where the second-phase particle size is similar to the size of the irradiated volume. If the composition difference between the two phases is large, the detected compositional fluctuations associated with varying phase fractions may mask any underlying composition gradient of the primary phase. The analysis technique was used to determine grain boundary chromium concentration gradients in a nickel-base superalloy, alloy X-750. The technique may also be of use in other alloy systems.

15th IEEE/NPSS Symposium. Fusion Engineering

During the Engineering Design Activity (EDA) of the ITER program a major effort is being devoted ... more During the Engineering Design Activity (EDA) of the ITER program a major effort is being devoted to conductor R&D for the ITER magnets systems. This program includes all aspects of cable-in-conduit-conductor (CICC) manufacturing development such as superconducting strand, large multistage cables, and fabrication of thick-wall and thin-wall conduits. It also includes an extensive program of small scale laboratory measurements and

Metallurgical Transactions A, 1992

INCOLOY 908 is a low coefficient of thermal expansion (COE) iron-nickel base superalloy that was ... more INCOLOY 908 is a low coefficient of thermal expansion (COE) iron-nickel base superalloy that was developed jointly by The Massachusetts Institute of Technology and the International Nickel Company for cryogenic service. The alloy is stable against phase transformation during prolonged thermal treatments and has a COE compatible with that of Nb3Sn. These properties make the material ideal for use as a structural component in superconducting magnets using Nb3Sn. The evolution of microstructure has been studied as a function of time at temperature over the temperature range of 650 °C to 900 °C for times between 50 and 200 hours. A detailed analysis of precipitated phases has been conducted using X-ray diffraction (XRD), transmission electron microscopy (TEM), and analytical scanning and scanning transmission electron mi- croscopy (STEM) techniques. The primary strengthening phase has been found to be γ′, Ni3(Al, Ti). INCOLOY 908 is stable against overaging, which is defined as the transformation of γ′ to η, Ni3Ti, for times to 100 hours at temperatures up to 750 °C. Upon overaging, the strengthening phase transforms to η. A new phase,H x , has been identified and characterized.

Metallurgical Transactions A, 1992

The electrochemical permeation technique has been used to characterize hydrogen transport and tra... more The electrochemical permeation technique has been used to characterize hydrogen transport and trapping in pure nickel and in alloys 600, X-750, and 718 at a temperature of 80 °C. The "effective diffusivity" of hydrogen atoms in alloy 600 is reduced by a factor of about 5 compared to pure nickel. This is attributed to both compositional changes and the presence of [(Ti, Nb)C] carbides. Aging of alloy 600, with subsequent M23C 6 carbide precipitation, does not significantly influence the measured "effective diffusivity," which is explained by the dominant effect of preexisting [(Ti, Nb)C] carbides. The "effective diffusivity" of hydrogen atoms in solution-annealed alloy X-750 is reduced by a factor of about 9 compared to that of pure nickel. This is also attributed to compositional changes and [(Ti, Nb)C] carbides. Aging of alloy X-750, which causes precipitation of y'[Ni3(A1, Ti)], reduces the "effective diffusivity" by an additional factor of 5 or more. Double aging at 885 °C/24 hours, 704 °C/20 hours following hot working yields the greatest reduction in "effective diffusivity." Analysis of permeation transients using a diffusiontrapping model indicates a binding energy associated with trapping due to the y' phase of between-31 and-37 kJ/mol. The "effective diffusivity" of hydrogen in alloy 718 is about 40 pct greater than for alloy X-750 for the same double and direct aging treatments. The average "effective diffusivities" of the double-aged and direct-aged alloy 718 are comparable, but the permeation transients for the double-aged treatment are significantly steeper. The double-aged treatment with predominantly 6 phase (orthorhombic Ni3Nb) yields a binding energy of about-30 kJ/mol. Analysis of the direct aged-treated 718, which contains predominantly 3/' phase (body-centered tetragonal Ni3Nb) gave a binding energy between-23 and-27 kJ/mol. Segregation of hydrogen atoms to the y'/matrix interface, combined with a large volume fraction of y' at grain boundaries, provides the most likely explanation for the enhanced cracking associated with the double-aging treatment in alloy X-750.

Journal of Testing and Evaluation, 1991

We review Charpy impact testing at extreme cryogenic temperatures, especially at liquid helium te... more We review Charpy impact testing at extreme cryogenic temperatures, especially at liquid helium temperature (4 K), considering methods of testing and calibration, thermal behavior during the various stages of testing, and correlations between Charpy absorbed energy and quantitative toughness parameters. Because of the very low specific heats of metals near absolute zero, any surface condensation of gases, convective or conductive heat transfer, or plastic deformation during a test will cause the specimen temperature to rise rapidly. Consequently, valid impact tests of alloys at 4 K can not be performed according to the procedure outlined in ASTM Methods E 23-88. During Charpy tests, the temperature of austenitic steel specimens, initially at or near 4 K, may in fact rise outside the cryogenic regime. Fracture does not occur at the intended temperature, but at an uncontrolled temperature, since materials with different work hardening rates heat differently. In view of the temperature rise variability and scatter in measurements and property correlations, we conclude that it is not possible to accurately estimate the 4 K fracture toughness of ductile steels, or rank them properly, using Charpy tests.

Journal of Nuclear Materials, 1976

Fusion Engineering and Design, 2006

Fusion research in the United States is sponsored by the Department of Energy's Office of Fusion ... more Fusion research in the United States is sponsored by the Department of Energy's Office of Fusion Energy Sciences (OFES). The OFES sponsors a wide range of programs to advance fusion science, fusion technology, and basic plasma science. Most experimental devices in the US fusion program are constructed using conventional technologies; however, a small portion of the fusion research program is directed towards large scale commercial power generation, which typically relies on superconductor technology to facilitate steady-state operation with high fusion power gain, Q. The superconductor portion of the US fusion research program is limited to a small number of laboratories including the Plasma Science and Fusion Center at

CORROSION, 1995

Page 1. CORROSION SCIENCE 651 CORROSION–Vol. 51, No. 9 0010-9312/95/ 000147/$5.00+$0.50/0 © 1995,... more Page 1. CORROSION SCIENCE 651 CORROSION–Vol. 51, No. 9 0010-9312/95/ 000147/$5.00+$0.50/0 © 1995, NACE International Submitted for publication August 1994; in revised form, January 1995. * Department of Nuclear ...

[Proceedings] The 14th IEEE/NPSS Symposium Fusion Engineering

At peak performance the Alcator C-Mod experiment at MIT will require pulses of up to 500 MJ over ... more At peak performance the Alcator C-Mod experiment at MIT will require pulses of up to 500 MJ over a 5 second period. This will be supplied by a commercial alternator supplemented by a 75 ton flywheel. When spun at 1800 rpm, the alternatorrotor combination stores a total kinetic energy of 2000 MJ. The safety analysis for the system must address several concerns, including fracture. To this end an extensive fracture mechanics analysis of the flywheel is being conducted. At present the initial flaw distribution has been determined by ultrasonic and magnetic particle examination. Material samples will be heat-treated to duplicate the thermal histories and properties of various locations within the singlepiece forging. A program of materials tests, including crack growth and fracture toughness, is being conducted for use in predicting the life of the flywheel.

The thermal aging and consequent embrittlement of materials are ongoing issues in cast and duplex... more The thermal aging and consequent embrittlement of materials are ongoing issues in cast and duplex stainless steel. Spinodal decomposition is largely responsible for the well known "475??C" embrittlement that results in drastic reductions in ductility and toughness in cast materials. This process is also operative in welds in either cast or wrought stainless steels where delta ferrite is present. While the embrittlement can occur after several hundred hours of aging at 475??C, it can also occur at lower temperatures where ductility reductions have been observed after several tens of thousands of hours at 300??C. The effect of thermal aging on mechanical properties, including tensile, toughness, fatigue and static crack growth has been investigated at room temperature and in 288??C high purity water simulating BWR operating conditions. The measurement of tensile, microhardness and Charpy-impact energy show an increase in strength and a decrease in impact energy after aging for up to 10,000 hours at 430 and 400 ??C. Stress Corrosion Crack (SCC) growth rates have been measured for material in the as-welded, 1000 hour/400??C and 5000 hour/400??C aged weld metal @ 288??C in high purity water containing 300ppb of Oxygen. Fracture toughness (J IC) have been measured in the 5000 hour/400??C aged condition and estimated in the other conditions. Crack growth rates for material in the as welded and aged for 5000 hours @ 400??C have been measured and are generally within the scatter band for wrought material although the aged material data fall at the high end. Unusual in-situ unstable fracture behavior has been experienced at toughness values significantly below (<50%) the room temperature fracture toughness for material that contains an SCC "precrack". In-situ fracture toughness with a fatigue precrack, is still significantly below the air values. This behavior, termed "environmental fracture" requires further investigation

Journal of Nuclear Materials, 2013

The corrosion characteristics of alloys F91 and Fe-12Cr-2Si in static lead-bismuth eutectic (LBE)... more The corrosion characteristics of alloys F91 and Fe-12Cr-2Si in static lead-bismuth eutectic (LBE) have been investigated at low (600-615°C) and high (700-715°C) temperatures, at oxidative and reductive oxygen potentials with respect to iron oxide formation. Very thin (100's of nm) interaction layers were observed for Fe-12Cr-2Si in both environments, while continued internal oxidation in oxidizing environments or selective liquid metal dissolution of chromium in reducing environments was observed in alloy F91. Fe-12Cr-2Si forms a protective system of Cr, Si, and Fe oxide layers upon exposure to LBE at both oxidizing and reducing oxygen potentials. The iron oxides are shown to disappear with increased exposure in LBE below the oxygen potential for Fe-oxide formation. Following this, a thin layer of more-protective silica forms beneath the chromia layer in both environments.

Advances in Cryogenic Engineering Materials, 1996

ABSTRACT

International Heat Treatment and Surface Engineering, 2010

ABSTRACT

AIP Conference Proceedings, 2006

ABSTRACT

Journal of electron microscopy technique, 1989

In this paper, we present a technique for analysis of composition gradients, using an analytical ... more In this paper, we present a technique for analysis of composition gradients, using an analytical electron microscope, within the primary phase of a two-phase alloy for the case where the second-phase particle size is similar to the size of the irradiated volume. If the composition difference between the two phases is large, the detected compositional fluctuations associated with varying phase fractions may mask any underlying composition gradient of the primary phase. The analysis technique was used to determine grain boundary chromium concentration gradients in a nickel-base superalloy, alloy X-750. The technique may also be of use in other alloy systems.

15th IEEE/NPSS Symposium. Fusion Engineering

During the Engineering Design Activity (EDA) of the ITER program a major effort is being devoted ... more During the Engineering Design Activity (EDA) of the ITER program a major effort is being devoted to conductor R&D for the ITER magnets systems. This program includes all aspects of cable-in-conduit-conductor (CICC) manufacturing development such as superconducting strand, large multistage cables, and fabrication of thick-wall and thin-wall conduits. It also includes an extensive program of small scale laboratory measurements and

Metallurgical Transactions A, 1992

INCOLOY 908 is a low coefficient of thermal expansion (COE) iron-nickel base superalloy that was ... more INCOLOY 908 is a low coefficient of thermal expansion (COE) iron-nickel base superalloy that was developed jointly by The Massachusetts Institute of Technology and the International Nickel Company for cryogenic service. The alloy is stable against phase transformation during prolonged thermal treatments and has a COE compatible with that of Nb3Sn. These properties make the material ideal for use as a structural component in superconducting magnets using Nb3Sn. The evolution of microstructure has been studied as a function of time at temperature over the temperature range of 650 °C to 900 °C for times between 50 and 200 hours. A detailed analysis of precipitated phases has been conducted using X-ray diffraction (XRD), transmission electron microscopy (TEM), and analytical scanning and scanning transmission electron mi- croscopy (STEM) techniques. The primary strengthening phase has been found to be γ′, Ni3(Al, Ti). INCOLOY 908 is stable against overaging, which is defined as the transformation of γ′ to η, Ni3Ti, for times to 100 hours at temperatures up to 750 °C. Upon overaging, the strengthening phase transforms to η. A new phase,H x , has been identified and characterized.

Metallurgical Transactions A, 1992

The electrochemical permeation technique has been used to characterize hydrogen transport and tra... more The electrochemical permeation technique has been used to characterize hydrogen transport and trapping in pure nickel and in alloys 600, X-750, and 718 at a temperature of 80 °C. The "effective diffusivity" of hydrogen atoms in alloy 600 is reduced by a factor of about 5 compared to pure nickel. This is attributed to both compositional changes and the presence of [(Ti, Nb)C] carbides. Aging of alloy 600, with subsequent M23C 6 carbide precipitation, does not significantly influence the measured "effective diffusivity," which is explained by the dominant effect of preexisting [(Ti, Nb)C] carbides. The "effective diffusivity" of hydrogen atoms in solution-annealed alloy X-750 is reduced by a factor of about 9 compared to that of pure nickel. This is also attributed to compositional changes and [(Ti, Nb)C] carbides. Aging of alloy X-750, which causes precipitation of y'[Ni3(A1, Ti)], reduces the "effective diffusivity" by an additional factor of 5 or more. Double aging at 885 °C/24 hours, 704 °C/20 hours following hot working yields the greatest reduction in "effective diffusivity." Analysis of permeation transients using a diffusiontrapping model indicates a binding energy associated with trapping due to the y' phase of between-31 and-37 kJ/mol. The "effective diffusivity" of hydrogen in alloy 718 is about 40 pct greater than for alloy X-750 for the same double and direct aging treatments. The average "effective diffusivities" of the double-aged and direct-aged alloy 718 are comparable, but the permeation transients for the double-aged treatment are significantly steeper. The double-aged treatment with predominantly 6 phase (orthorhombic Ni3Nb) yields a binding energy of about-30 kJ/mol. Analysis of the direct aged-treated 718, which contains predominantly 3/' phase (body-centered tetragonal Ni3Nb) gave a binding energy between-23 and-27 kJ/mol. Segregation of hydrogen atoms to the y'/matrix interface, combined with a large volume fraction of y' at grain boundaries, provides the most likely explanation for the enhanced cracking associated with the double-aging treatment in alloy X-750.

Journal of Testing and Evaluation, 1991

We review Charpy impact testing at extreme cryogenic temperatures, especially at liquid helium te... more We review Charpy impact testing at extreme cryogenic temperatures, especially at liquid helium temperature (4 K), considering methods of testing and calibration, thermal behavior during the various stages of testing, and correlations between Charpy absorbed energy and quantitative toughness parameters. Because of the very low specific heats of metals near absolute zero, any surface condensation of gases, convective or conductive heat transfer, or plastic deformation during a test will cause the specimen temperature to rise rapidly. Consequently, valid impact tests of alloys at 4 K can not be performed according to the procedure outlined in ASTM Methods E 23-88. During Charpy tests, the temperature of austenitic steel specimens, initially at or near 4 K, may in fact rise outside the cryogenic regime. Fracture does not occur at the intended temperature, but at an uncontrolled temperature, since materials with different work hardening rates heat differently. In view of the temperature rise variability and scatter in measurements and property correlations, we conclude that it is not possible to accurately estimate the 4 K fracture toughness of ductile steels, or rank them properly, using Charpy tests.

Journal of Nuclear Materials, 1976

Fusion Engineering and Design, 2006

Fusion research in the United States is sponsored by the Department of Energy's Office of Fusion ... more Fusion research in the United States is sponsored by the Department of Energy's Office of Fusion Energy Sciences (OFES). The OFES sponsors a wide range of programs to advance fusion science, fusion technology, and basic plasma science. Most experimental devices in the US fusion program are constructed using conventional technologies; however, a small portion of the fusion research program is directed towards large scale commercial power generation, which typically relies on superconductor technology to facilitate steady-state operation with high fusion power gain, Q. The superconductor portion of the US fusion research program is limited to a small number of laboratories including the Plasma Science and Fusion Center at

CORROSION, 1995

Page 1. CORROSION SCIENCE 651 CORROSION–Vol. 51, No. 9 0010-9312/95/ 000147/$5.00+$0.50/0 © 1995,... more Page 1. CORROSION SCIENCE 651 CORROSION–Vol. 51, No. 9 0010-9312/95/ 000147/$5.00+$0.50/0 © 1995, NACE International Submitted for publication August 1994; in revised form, January 1995. * Department of Nuclear ...

[Proceedings] The 14th IEEE/NPSS Symposium Fusion Engineering

At peak performance the Alcator C-Mod experiment at MIT will require pulses of up to 500 MJ over ... more At peak performance the Alcator C-Mod experiment at MIT will require pulses of up to 500 MJ over a 5 second period. This will be supplied by a commercial alternator supplemented by a 75 ton flywheel. When spun at 1800 rpm, the alternatorrotor combination stores a total kinetic energy of 2000 MJ. The safety analysis for the system must address several concerns, including fracture. To this end an extensive fracture mechanics analysis of the flywheel is being conducted. At present the initial flaw distribution has been determined by ultrasonic and magnetic particle examination. Material samples will be heat-treated to duplicate the thermal histories and properties of various locations within the singlepiece forging. A program of materials tests, including crack growth and fracture toughness, is being conducted for use in predicting the life of the flywheel.

The thermal aging and consequent embrittlement of materials are ongoing issues in cast and duplex... more The thermal aging and consequent embrittlement of materials are ongoing issues in cast and duplex stainless steel. Spinodal decomposition is largely responsible for the well known "475??C" embrittlement that results in drastic reductions in ductility and toughness in cast materials. This process is also operative in welds in either cast or wrought stainless steels where delta ferrite is present. While the embrittlement can occur after several hundred hours of aging at 475??C, it can also occur at lower temperatures where ductility reductions have been observed after several tens of thousands of hours at 300??C. The effect of thermal aging on mechanical properties, including tensile, toughness, fatigue and static crack growth has been investigated at room temperature and in 288??C high purity water simulating BWR operating conditions. The measurement of tensile, microhardness and Charpy-impact energy show an increase in strength and a decrease in impact energy after aging for up to 10,000 hours at 430 and 400 ??C. Stress Corrosion Crack (SCC) growth rates have been measured for material in the as-welded, 1000 hour/400??C and 5000 hour/400??C aged weld metal @ 288??C in high purity water containing 300ppb of Oxygen. Fracture toughness (J IC) have been measured in the 5000 hour/400??C aged condition and estimated in the other conditions. Crack growth rates for material in the as welded and aged for 5000 hours @ 400??C have been measured and are generally within the scatter band for wrought material although the aged material data fall at the high end. Unusual in-situ unstable fracture behavior has been experienced at toughness values significantly below (<50%) the room temperature fracture toughness for material that contains an SCC "precrack". In-situ fracture toughness with a fatigue precrack, is still significantly below the air values. This behavior, termed "environmental fracture" requires further investigation

Journal of Nuclear Materials, 2013

The corrosion characteristics of alloys F91 and Fe-12Cr-2Si in static lead-bismuth eutectic (LBE)... more The corrosion characteristics of alloys F91 and Fe-12Cr-2Si in static lead-bismuth eutectic (LBE) have been investigated at low (600-615°C) and high (700-715°C) temperatures, at oxidative and reductive oxygen potentials with respect to iron oxide formation. Very thin (100's of nm) interaction layers were observed for Fe-12Cr-2Si in both environments, while continued internal oxidation in oxidizing environments or selective liquid metal dissolution of chromium in reducing environments was observed in alloy F91. Fe-12Cr-2Si forms a protective system of Cr, Si, and Fe oxide layers upon exposure to LBE at both oxidizing and reducing oxygen potentials. The iron oxides are shown to disappear with increased exposure in LBE below the oxygen potential for Fe-oxide formation. Following this, a thin layer of more-protective silica forms beneath the chromia layer in both environments.