Metallurgy of Zircaloy-2. Part I. The Effects of Fabrication Variables on the Anisotropy of Mechanical Properties

The anisotropy of mechanical propertles of Zircaloy-2 was studied as a function of fabricatlon variables. The variatlon in tensile and impact properties with specimen orientation was taken as the measure of the anisotropy of mechanical properties for each material. A qualitative separatlon of the effects of the fabrication variables on the resulting anisotropy of mechanical properties is made, but it is valid only in the rolling plane of the plate. A contractile strain ratio, a ratio of the nataral contractile strain in the rolling plane to that in the direction normal to the rolling plane (measured on the round tensile specimen after testing), is introduced to aid in the interpretation of the tensile data. A Zircaloy-2 fabrication schedule (consisting of, in succession, ingot breakdown at a temperature of 1800 to 1900 gas-cooled F, major reduction at a temperature of 1800 to 1900 or 1350 to 1450 gas-cooled F, a to 1000 deg F. heat treatment of 1800 to 1850 gas- cooled F for 30 min, followed by either a water-quench or a rapid aircool to below 1200 gas-cooled F, a final reduction of 25 to 40% at l000 gas-cooled F, and an anneal at 1400 to 1425 gas-cooled F for 30 min) was found to produce a much more nearly isotropic material than any of the schedules investigated. This material is anisotropic in strain behavior and tensile properties in comparison to the common cubic materials. The elimination of the intermediate to 1000 deg F. heat treatment from the fabrication schedule resulted in the production of a material with tensile properties for all directions in the plane of rolling essentially the same, but which allowed little cortractile strain to occur in the thickness direction of the plate. This indicated that a high degree of three-dimensional anisotropy existed in the material. The effect of cross rolling on the anisotropy of mechanical properties of Zircaloy-2 was found to be a function of the temperature and stage of fabrication at which it was performed, the position of the relative to the final fabrication directions, and the type of cross rolling, whether unidirectional or rotational. It was concluded that the use of other methods of examination and interpretation was necessary to satisfactorily evaluate the effects of variation of the fabrication variables on the anisotropy of Zircaloy-2. (auth

METALLURGY OF ZIRCALOY-2. PART II. THE EFFECTS OF FABRICATION VARIABLES ON THE PREFERRED ORIENTATION AND ANISOTROPY OF STRAIN BEHAVIOR

The preferred orientation and anisotropy of strain behavior of Zircaloy- 2 were studied as functions of fabrication variables. An inverse-pole-figure technique was used for the preferred orientation determinations. Evaluation of the effects of the fabrication variables on the anisotropy of strain behavior was accomplished by a contractile strainaxial strain analysis. An analysis of strain behavior in the normal direction was developed on the basis of theory of plastic flow of anisotropic metals. A simple intuitively derivable relation was found to exist between the strainstrain analysis and the preferred orientation data. Correlations of the strain-strain data with true-stress-truestrain diagrams and mechanical properties were attempted. The preferred orientation of Zircaloy-2 produced by the Oak Ridge National Laboratory-Homogeneous Reactor Project (ORNL- HRP) metallurgy fabrication schedule (ingot breakdown at 1500 to 1900 deg F, major reduction at 1800 to 1900 deg F or 1350 to 1450 deg F, a heat treatment of 30 min at 1800 at 1550 deg F followed by a water quench or rapid air cool to below 1200 deg F, a final reduction of 25 to 40% at 1000 deg F. and a 3O-min anneal at 1400 to 1425 deg F) was weak compared to that of most of the other schedules investigated. Elimination of the beta heat treatment (1800 to 1850 deg F for 30 min) between the major reduction and final reduction steps resulted in a material with a high degree of preferred orienation and with a state of pseudoisotropy in ihe rolling plane. A unique and quite high degree of preferred orientaion was developed when the ORNL-HRP metallurgy fabrication procedure was used, but the ingot axis was in the transverse rather than the rolling direction of the finished plate permitting more contractile sirain to occur in the normal direction than in either the rolling or transverse directions. The strain-strain analyses of the materials were consistent with the conclusions reached by the preferred orientation analyses. The effects of cross rolling on the anisotropy of strain behavior of Zircaloy-2 were found to depend on the type of cross rolling (unidirectional or rotational), the temperature of cross rolling, and the stage of fabrication at which the cross rolling was done. Unidirectional cross rolling at 1000 deg F after beta heat treatment caused only a slight increase in anisotropy of strain behavior over that for straight-rolled material, but roiational cross rolling at 1000 deg F after beta heat treatment resulted in a material with a state of isotropy of strain behavior only in the rolling plane. Rotational cross rolling before beta heat treatment, for one material at 1450 deg F and for another from 1900 deg F, produced different states or degrees of anisotropy of strain behavior. Because of flow constraints which exist in sheettype tensile specimens with width-to-thickness ratios > 1.0, it is imperative that round tensile specimens be used in the contractile strain-axial strain analysis. Since the principal axes of anisotropy are generally not the major sheet directions, they must be found by the preferred orientation analysis. (auth

The present and future of QCD

This White Paper presents an overview of the current status and future perspective of QCD research, based on the community inputs and scientific conclusions from the 2022 Hot and Cold QCD Town Meeting. We present the progress made in the last decade toward a deep understanding of both the fundamental structure of the sub-atomic matter of nucleon and nucleus in cold QCD, and the hot QCD matter in heavy ion collisions. We identify key questions of QCD research and plausible paths to obtaining answers to those questions in the near future, hence defining priorities of our research over the coming decades

EXAMINATION OF Zr AND Ti RECOMBINER LOOP SPECIMENS

Cold-worked specimens of iodide zirconium, Zircaloy-2, iodide titanium, and A-55 titanium were tested in a high-pressure recombiner loop in an attempt to duplicate anomalous results obtained in a prior recombiner loop. Hydrogen analyses and metallographic examinations were made on all specimens. The titanium materials and Zircaloy-2 picked up major amounts of hydrogen in the cell section. None of the materials tested showed appreciable hydrogen absorption in the recombiner section. Complete recrystallization occurred in all cell specimens while only Zircaloy-2, of the recombiner specimens, showed any degree of recrystallization. No explanation for this behavior can be given. A survnnary of the data obtained in previous recombiner loops is compared with the results of this loop. Conclusions were based on the results of three recombiner loops. Primarlly because of the hydrogen absorption data obtained in all three recombiner loops it is recommended that the zirconium and titunium materials tested not be used in environments similar to those encountered in high pressure recombiner loops. (auth

HTGR structural-materials efforts in the US

The status of ongoing structural materials programs being conducted in the US to support development and deployment of the high-temperature gas-cooled reactor (HTGR) is described. While the total US program includes work in support of all variants of this reactor system, the emphasis of this paper is on the work aimed at support of the steam cycle/cogeneration (SC/C) version of the HTGR. Work described includes activities to develop design and performance prediction data on metals, ceramics, and graphite

Relationship between carburization and zero-applied-stress creep dilation in Alloy 800H and Hastelloy X. [HTGR]

Typical HTGR candidate alloys can carburize when exposed to simulated service environments. The carbon concentration gradients so formed give rise to internal stresses which could cause dilation. Studies performed with Hastelloy X and Alloy 800H showed that dilations of up to almost 1% can occur at 1000/sup 0/C when carbon pickup is high. Dilation was normally observed only when the carbon increase was >1000 ..mu..g/cm/sup 2/ and ceased when the diffusing carbon reached the center of the specimen

EXAMINATION OF HIGH PRESSURE RECOMBINER LOOP SPECIMENS

Speciments of iodide zirconium, Zircaloy-2, Zr-15Nb, iodide titanium, TMCA-45 titanium, A-110AT titanium, and 430 stainless steel were corroded in a highpressure recombiner loop. Analyses were performed to determine the amount of hydrogen pickup. The titanium materials and iodide zirconium showed very high hydrogen pickups, while the zirconium alloys and the 430 stainless steel absorbed smaller amounts of hydrogen Metallographic examination of the specimens showed that recrystallization occurred in all but the Ar-15Nb specimens. There seems to be little difference in the extent of recrystallization and grain growth whether the in the recombiner section at 430 to 500 deg C. Recrystalliplained or correlated in any way with the amount of f hydrogen sion that occured. Since hydrogen is known to seriously embrittle zirconium and titanium, it is recommended that crystal-bar zirconium and titanium alloys not be used as materials of construction in environ ments sinmilar to that of the High Pressure Recombiner Loop. (auth

Long-term creep testing of 2 1/4 Cr-1 Mo steel in HTGR helium

Long-term creep tests have been conducted on three heats of 2 1/4 Cr-1 Mo ferritic steel, a candidate alloy for a number of applications in gas-cooled reactors. These tests, run at temperatures from 482 to 649/sup 0/C, have reached times of 40,000 h and greater. Essentially no effect of environment, either air or simulated gas-cooled reactor helium, was seen at temperatures up to about 600/sup 0/C. At the highest test temperature the creep behavior of the steel was degraded both by oxidation in air (fall off in creep resistance and lower creep ductility) and decarburization in gas-cooled reactor helium (lower creep resistance). 5 figures