Abstract: An apparatus for in-situ measurement of residual surface stresses comprises a compact x-ray tube and a detector. X-rays emitted by the x-ray tube are diffracted from a specimen surface and intercepted by the detector. The intercepted x-rays are converted into light and transferred by a first fiber optic bundle and a second fiber optic bundle to light detection devices. Intensities of the received light are digitized by the light detection devices to generate a first ring and a second ring with common centers. The residual stress in the specimen surface is calculated based on a difference between the radii of the first ring and the second ring.

Abstract: A radioisotope based x-ray residual stress analysis apparatus having a shielded, monoenergetic radioisotopic source to emit x rays for measurement of the stress state of a polycrystalline material. The isotropic source is selected from spontaneously emissive radioisotopes emitting photons in the 5-100 keV energy range. The emissions of the source assembly are measured using either a conventional, solid-state, position sensitive detector or a gas filled position sensitive proportional counter (PSPC). In addition to normal residual stress analysis, the use of a PSPC allows the identification of characteristic photons emitted by particular isotopes to identify trace elements within a sample. As a result of the minimal shielding required for the source assembly and the small size of the isotropic source, the x-ray residual stress analysis apparatus of the present invention is uniquely suited to be configured with an area detector.

Abstract: A method for characterizing a structure including single-crystal silicon-germanium areas on a single-crystal silicon substrate, including the steps of measuring the X-ray diffraction spectrum of the structure, simulating the diffraction spectrum of a single-crystal silicon substrate, simulating the diffraction spectrum of a single-crystal silicon substrate entirely coated with a single-crystal SiGe layer, adding the simulated spectrums while assigning them weights a and 1-a to obtain a sum spectrum, comparing the sum spectrum with the measured spectrum and adjusting the simulation parameters and weight a to reduce the distance between the sum spectrum and the measured spectrum, and after optimizing, adopting the simulation parameters as the measurement parameters.

Abstract: A method of determining if an alloy article (28) has any remaining working life comprises taking a sample from an alloy article (28) and removing all metal matrix material from the sample to leave the carbide particles. The carbide particles are analysed using x-ray diffraction to determine the ratio of the amount of the M23C6 carbide phase to the amount of the MC carbide phase. This ratio is compared with a database, containing the ratio of the amount of the M23C6 carbide phase to the amount of the MC carbide phase as a function of temperature of heat treatment and time of heat treatment, to determine the temperature of heat treatment and the time of heat treatment of the sample of the alloy article (28). This is compared with a database of heat treatment temperatures and associated heat treatment times corresponding to the full working life of the alloy article (28) to determine if the alloy article (28) has any remaining working life.

Abstract: An x-ray diffraction system for determining stress in integrated circuit materials includes a source of x-rays (3) that are directed toward a sample holding mechanism for diffracting from the test sample (8). An x-ray detector (14) is arranged for detecting high back reflected diffracted x-ray intensity data representing stress in the test sample. A two-dimensional detection and storage arrangement (24) is arranged for detecting and storing the data representing stress in the test sample. A data processor (2) accesses the stored data from the two-dimensional detection and storage arrangement and processes the data representing stress in the test sample to determine stress in the test sample.

Abstract: Improved methods for managing a population of metal components subject to fatigue failure are provided. The residual compressive stress in the critical surfaces of such components, especially in areas of high stress concentration, are measured non-destructively using x-ray diffraction techniques. The measured surface residual compressive stress is used as a management criterion. A component having a surface residual compressive stress greater than a predetermined value can be returned to service. However, once the measured surface residual compressive stress of a component falls below the predetermined value, it can either be removed permanently from service, or it can be reworked to increase its surface residual compressive stress and then returned to service. Additionally, by measuring the surface residual compressive stress of an individual component, the remaining service life of that individual component can be estimated.

Abstract: Improved methods for managing a population of metal components subject to fatigue failure are provided. The residual compressive stress in the critical surfaces of such components, especially in areas of high stress concentration, are measured non-destructively using x-ray diffraction techniques. The measured residual compressive stress is used as a management criteria. A component having a residual compressive stress greater than a predetermined value can be returned to service. However, once the measured residual compressive stress of a component galls below the predetermined value, it can either be removed permanently from service, or it can be reworked to increase its residual compressive stress and then returned to service. Additionally, by measuring the residual compressive stress of an individual component, the remaining service life of that individual component can be estimated.

Abstract: Measurements are made on a sample (1) to obtain an experimental profile (2) having structural features (3, 4) determined at least in part by the given characteristic and an expected profile (5) calculated for the sample using selected parameters. A degree of smoothing is applied to the experimental profile (2) to reduce the structural features (3,4) thereby producing a smoothed experimental profile (21 a) and the same degree of smoothing is applied to the calculated profile (5) to produce a smoothed calculated profile 51 a. The smoothed calculated profile (51 a) is compared with the smoothed experimental profile (21 a) to determine the difference between the smoothed profiles. The calculated profile is then modified by varying at least one of the parameters until the smoothed modified profile fits the smoothed experimental profile.

Abstract: An accurate, real-time method for monitoring and analyzing crystalline specimens having polycrystalline platings. The method is capable of individual or simultaneous analysis of any combination of the following: 1) composition of the substrate and plating (even when the plating and substrate having common elements); 2) analysis of thickness of the plating(s); 3) analysis of the depth of the plating(s), e.g., the thickness of any overlay; 4) analysis of the crystalline phase depth simultaneous with phase composition; 5) the preferred crystalline orientation; 6) the strain in the substrate; and (7) crystallinity and grain size. The apparatus is similar to that of U.S. Pat. No. 5,148,458 issued to Ruud, with the apparatus of this invention having the several detectors placed on different arcs and/or radial distances from the specimen surface under investigation.

Abstract: The process measures a characteristic (X) which is difficult to measure of a continuously produced product and comprises:choosing at least one easily measurable second characteristic (Y) whose variations are correlated to the variations of the first characteristic;modifying, by means acting on the product in a given zone of the production line, the first characteristic so as to put it into a known predetermined reference state (X.sub.o);taking at least in said zone a measurement of the second characteristic, and;processing said measurement for determining a variation in the first characteristic relative to the reference state (X).Application in the measurement of the flatness of a strip continuously travelling through a levelling machine.FIG. 2.

Abstract: A method of evaluating the degree of fatigue in a material to be inspected before the occurrence of a microcrack from data measured nondestructively through the measurement of diffracted beams of X-rays. A fatigue test is performed by applying a predetermined class of repeating stress predicted in a service environment of the material to be inspected to a reference piece of a quality corresponding to the material. A diffracted X-ray measurement is performed on the reference piece at a plurality of points of time during the fatigue test so that in accordance with the measurement results a fatigue characteristic curve is obtained which corresponds to the relation between the integrated amounts of the repeating stress and the intensities of the diffracted beams of X-rays.

Abstract: It is often important to measure the phase composition and residual stress resultant from many materials processing procedures. For example, the carburization and heat treatment of steel components where the phase content of austenite versus ferrite or martensite, and residual stress are important characteristics with respect to the ultimate performance of the component. The x-ray diffraction techniques are used extensively to measure both of these characteristics of steel parts. However, the procedures for these measurements are time consuming and must be performed sequentially with any x-ray instrument except that of the present invention. This invention describes a method and apparatus that is able to perform the measurement of retained austenite and residual stress simultaneously. The advantages that the invention offers include very short measurement times and measurement of the characteristics in exactly the same spot of a sample at the same time.

Abstract: A circuit configuration for synchronizing pulse-shaped signals includes a clock-controlled flip-flop having a data input for receiving a pulse-shaped signal to be synchronized, a data output for supplying a synchronized signal, and a clock input. A test circuit has an input connected to the data input of the clock-controlled flip-flop for receiving the pulse-shaped signal to be synchronized, another input for receiving at least one clock signal, and an output connected to the clock input of the clock-controlled flip-flop. The test circuit generates an output signal at the output of the test circuit to be supplied to the clock input of the clock-controlled flip-flop being either equal to or phase-offset relative to the at least one clock signal supplied to the other input of the test circuit. The test circuit ascertains a phase difference between an edge of the pulse-shaped signal to be weighted and a weighting edge of the output signal of the test circuit.

Abstract: Procedure based on X-ray diffraction for measuring the stress state of metals, in particular austenitic steels. In the procedure the detector surface (10) is inclined about an axis (A--A) lying on the surface of the sample (20) being examined which is substantially perpendicular to the direction of the stresses (.sigma..sub.xx) being examined. By means of the detector surface (10) the diameters (2S.sub.ax) of the so-called Debye rings in the direction of the surface being examined are recorded at two or several inclination angles (.psi.). The detector surface (10) has arcuate shape, as viewed in the direction (B--B) at right angles against the inclination axis (A--A), and in the procedure is used such as arcuate detector surface (10) elongated in the direction of said inclination axis (A--A) and narrow enough in the opposite direction that an inclination angle (.psi.) of the detector surface (10) large enough in view of the procedure's implementation is feasible.

Abstract: A method for estimating the press formability of galvannealed steel sheets provided, wherein: the values found by: ##EQU1## wherein I(.gamma.)=the total X-ray diffraction intensity of the .gamma. phase,I(.GAMMA.)=the total X-ray diffraction intensity of the .GAMMA. phase,I.sub.B (.gamma.)=the background X-ray diffraction intensity of the .gamma. phase,I(.gamma.)-I.sub.B (.gamma.)=the true X-ray diffraction intensity of the .gamma. phase,I(.GAMMA.)-I.sub.B (.GAMMA.)=the true X-ray diffraction intensity of the .GAMMA. phase,.GAMMA.=the .GAMMA. phase of an Fe-Zn intermetallic compound in coating of galvannealed steel sheet, and.gamma.=the .gamma. phase of the intermetallic compound, are used as an index to determine the press formability.

Abstract: Diffractometer data is collected without the use of a movable receiving s. A scanning device, positioned in the diffractometer between a sample and detector, varies the amount of the beam diffracted from the sample that is received by the detector in such a manner that the beam is detected in an integrated form. In one embodiment, a variable diameter beam stop is used which comprises a drop of mercury captured between a pair of spaced sheets and disposed in the path of the diffracted beam. By varying the spacing between the sheets, the diameter of the mercury drop is varied. In another embodiment, an adjustable iris diaphragm is positioned in the path of the diffracted beam and the iris opening is adjusted to control the amount of the beam reaching the detector.

Abstract: In analyzing the texture of rolled metal sheets and strips by means of X-rays or .gamma.-rays that penetrate them, the total beam emitted by the source of radiation is divided by collimators into several component beams, and each component beam is aimed at a different angle at a component area of the sheet or strip being tested. The diffracted radiation that penetrates the sheet is analyzed in accordance with its energy distribution in detectors and the results are processed in a computer.

Abstract: A method and apparatus for orienting a pulsed neutron source and a multi-angle diffractometer toward a sample of a ceramic-matrix or metal-matrix composite so that the measurement of internal strain (from which stress is calculated) is reduced to uncomplicated time-of-flight measurements.

Abstract: A process for improving the technique of measuring residual stress by x-ray diffraction in pieces of nickel-base alloys which comprises covering part of a predetermined area of the surface of a nickel-base alloy with a dispersion, exposing the covered and uncovered portions of the surface of the alloy to x-rays by way of an x-ray diffractometry apparatus, making x-ray diffraction determinations of the exposed surface, and measuring the residual stress in the alloy based on these determinations. The dispersion is opaque to x-rays and serves a dual purpose since it masks off unsatisfactory signals such that only a small portion of the surface is measured, and it supplies an internal standard by providing diffractogram peaks comparable to the peaks of the nickel alloy so that the alloy peaks can be very accurately located regardless of any sources of error external to the sample.

Abstract: An X-ray analyzer for performing both X-ray fluorescence and X-ray diffraction analysis is provided with an X-ray source, an X-ray guide tube for collimating X-rays from the source, a vacuum tank in which the guide tube is partially disposed, a rotatable sample table for holding a sample adjacent the guide tube, and an X-ray detector movable away from and towards the sample table, and also rotatable independently of the sample table.

Abstract: A method and apparatus is disclosed for measuring the lattice parameters of single crystal material while that material is undergoing a transient shock wave. In a first embodiment, a first target is located at a preselected position in space with respect to a single crystal to be measured. A first laser beam pulse is transmitted through a beam block to the crystal to produce a transient shock wave in part of the crystal. A second laser beam pulse, synchronized to the first laser beam pulse, is transmitted to the first target to cause the first target to produce first and second sets of x-rays which are Bragg-diffracted from shocked and unshocked atomic planes of the crystal as the crystal is undergoing the shock wave. A first x-ray detector records the positions of the first and second sets of Bragg-diffracted x-rays to provide a first measurement of the lattice parameters of the crystal.

Abstract: A method for evaluating a residual fatigue life of mechanical parts, consisting of the steps of grinding a surface layer of a mechanical part to be inspected by a minute amount to form an inspection surface, measuring half-width data of an X-ray diffraction intensity curve on the inspection surface, calculating a depth (do) of a fatigue damaged region from a graph of a half-width ratio (H/Ho) versus a depth (d) below the surface layer, and determining a fraction of fatigue life N/Nf on the basis of data of the depth (do) of the defective region versus the fraction of fatigue life N/Nf which were separately obtained from a test piece.

Abstract: Previous methods for determining internal stress in polycrystalline solids by X-ray diffraction techniques have required that the distance between the X-ray irradiated surface of the sample under investigation and the X-ray detection surface for the diffracted X-rays be known. According to the practice of this invention, stress measurement can be made without determining the sample to detector distance as a separate step. Two or more sets of detection surfaces, i.e., X-ray detector channels, are arranged around the incident X-ray beam, usually on opposite sides of the cone of diffracted X-rays from one another. The invention employs a calibration procedure which provides a set of calibration parameters, which, when used with X-ray stress equations, yields accurate internal stress measurement without the prior art requirement of determining the sample to detector distance.

Abstract: A portable X-ray diffractometer for measurement of residual stress in metallic specimens, especially large structures, such as bridges, pipelines etc. The instrument consists of a pair of position sensitive detectors arranged to be mounted in fixed positions relative to the specimen. An X-ray source that projects a collimated incident beam onto the area of the specimen under examination is located between the detectors so that each receives a diffraction line. The source is scanned stepwise in an arc about the specimen area, while the specimen and both the detectors remain fixed. The diffraction lines received in each detector are stored in a computer as histograms of intensity values. For each angular relationship between the incident beam and the chosen direction of strain measurement, a series of such intensity values corresponding to a given diffraction angle for successive diffraction lines is averaged and a resultant diffraction line obtained for each detector.

Abstract: A polycrystalline sample is irradiated with a collimated beam of substantially monochromatic X-ray radiation to form a diffraction come which extends and expands outwardly from the sample. A substantially planar, two-dimensional, position sensitive detector is disposed across the cone to intercept and thereby form a two-dimensional image of at least a substantial portion of the cone's cross-sectional periphery. A theoretical relationship exists between the shape of the cone's image and the residual stress in the sample such that the image can be analyzed to quantitatively determine the residual stress.

Abstract: The X-ray diffraction apparatus of the invention includes means capable of detecting the position and intensity distribution of the diffracted X-ray with respect to a thin bundle X-ray and means for moving the former means to a position at which the former means is capable of detecting the diffracted X-ray, and makes it possible to reliably and easily carry out rough detection of the position of the diffracted X-ray and fine detection of the intensity distribution of the diffracted X-ray without increasing the size of the diffracted X-ray detecting means.

Abstract: Provided is a method for foreseeing the residual life of a structural member, making use of an X-ray, comprising: preparing a plurality of test pieces made of the same material and subjected to the same working and heat-treating conditions as the structural member to be examined of which the fatigue strength is in question; executing fatigue tests with said test pieces till failure under a plurality of different stress conditions; obtaining for each stress the relationship between the residual life of said test piece and the halfvalue width ratio of X-ray diffraction profile; determining, from the above-mentioned relationships, a first relationship region between the halfvalue width ratio and the residual life that is independent of the level of the stress; measuring the halfvalue width ratio of said structural member; and determining the residual life of said structural member from the measured halfvalue width ratio in accordance with said first relationship region.

Abstract: A method of determining fatigue life of metals that are subject to the cyclic load. A metal that exhibits a half-value width that varies depending upon the degree of deformation by fatigue is melt-adhered onto a recessed portion formed in a metal of which the life is to be determined. The two metals are subjected to the cyclic load simultaneously. Then, the melt-adhered metal is irradiated with an X-ray, and a half-value width of an S-N curve of the resulting diffracted X-ray is measured, thereby to determine the fatigue life of the metal of which the life is to be estimated. The method is effective for accurately determining the life even for the metals which exhibit half-value widths that change very little depending upon the degree of deformation by fatigue.