Nondestructuctive testing of stress states in samples and products are performed by different methods. Among them are well-known X-ray methods called X-Ray Tensometry. This paper describes: - the outline of development of stress states testing by X-ray methods in Poland, - the scientific literature main by books in this branch in Poland. For important papers of X-ray tensometry in Poland belong: Ziolowski Z., X-Ray Method of Stress Determination in Metals Kasprzak W., Measurement of the Deformation State in the Area of One Grain Range of a Polycrystal by Means of X-Rays Mikiewicz T., Recovery in Mild Steel Treated with Aluminium Karp J., Zapalska-Nowal K, The Application of X-Ray Radiography to Determine the Strain of the Structural Lattice of Cast Steel Kasprzak W., Theoretical Principles of Measurements Methods of Strain State and Derivative Values Hebda M., Selected Methods of Experimental Analysis of Internal Stresses in the Surface Layer Senczyk D., The Analytical Methods of a Precise Defining of the Angular Diffraction Line Position in the Methods of Very Accurate Macrostresses and Lattice Constants Measurements Senczyk D., The Simultanous Defining Method of the 1st and 2nd Kind of Stress and the Mosaic Blocks Parameters Defining Based on the Angular Intensity Distribution of Diffraction Line Analysis Sencyk D., Seeming Variation of Interplanar Distance of Broad Diffraction Line in Metals and Alloys X-Ray Analysis Senczyk D., Accuracy Analysis Determination of Interplanar Distance by Some Precision X-Ray Methods Pszonka A., Ziaja J., X-Ray Methods of Measurements of Stresses Kasprzak W., Pszonka A., Ziaja J., Determination of The State of Strain in Single Crystalites of the Regular System with the Help of X-Rays Pszonka A., Ziaja J., Proposal of Measuring The State of Strain in a Single Crystallite of a Polycrystal Test Piece With The Diffractometric Method Pszonka A., Ziaja J., Quick Determination of the X-Ray Peak at Stress Measurements Senczyk D., X-Ray Laboratory Ziaja J.. X-Ray Diffraction Methods of Determining the Real Structure Parameters of a Polycrystalline Material Frydman S., X-Ray Measurements of Elastic Constants un - and -Brasses Senczyk D., The Analysis of Error Sources and Experimental Determination of Precision in Measurements of Macrostresses by X-Ray Methods for Chosen Polycrystalline Materials Sencyk D., X-Ray Methods and Technics for Materials Structure Investigations Senczyk D., Macrostress Measurements in polycrystalline Materials by X-Ray Methods Senczyk D., X-Ray Diffractometry in Stress States Investigations and Elastic Properties of Polycrystalline Materials Senczyk D., Internal Stresses. Introduction to generation, control and application

1) Ziolowski Z., X-Ray Method of Stress Determination in Metals,
Scientific Papers of Institutes of Ministry of Metallurgy, p. 252 . 225, 1957 (in polish).

On the basis of extensive theoretical background the author discusses the methods of X-ray determination of main stresses and their directions. Investigations followed by an analysis of errors have shown, that the obtained accuracy is not of a very high order and depends upon a number of factors. In industrial applications, when determining the conditions of residual stresses, an approximate information on stress magnitude is frequently sufficient. A modified method of "oblique screened photographs" has been worked out for this purpose, the photographs were made by means of a gap screen. This method makes possible a rapid and simple determination of the sign and the magnitude of stress components directly from one X-ray diagram. The technique which was worked out by the author of making photographs made possible the shortening the time of exposures from several hours to under an hour. In order to make stress photographs from objects of venous sizes special appliances were build, such as: transportable hood for the X-ray camera together with a support and a device for aligning the apparatus venous types of X-ray cameras for back exposures equipped with movable diaphragms, section screens and transmission gears. Methods of measurement and of calculation of stresses from diagrams made by conventional and rapid methods are described and illustrated. In order to establish the causes of closing of tabular cells during the miring and straightening of railway rails the deposition of longitudinal stresses on rail surfaces has been determined Investigations have confirmed the assumption that the closing of tubular cells is due to a partial deformation of the web and the flange of rails made during the straightening operation.

2) Kasprzak W., Measurement of the Deformation State in the Area of One Grain Range of a Polycrystal by Means of X-Rays,
Scientific Papers of Wroclaw Technical University, No 46, Series: Mechanics, No VII, p. 55 243, 1961 (in polish)

Investigations presented in this paper deal with the X-ray radiographic measurements of the stress, and the author comes to the following conclusions:
The methods of interpretation of strain measurements by means of X-rays, given by Ageev [Ageev V. A., Zurnal Techniceskoj Fiziki, 1958, v. XXV111, No 11, p. 2515] and Glocker [Glocker R., Verfahren und Einrichtungen zur röntgenographischen Spannungsmessung, Handbuch der Werkstoffprüfung, Springer, Berlin, 1958] assume the continuous structure of the tested material. Such an assumption is contradictory to the physical principles of measuring, and for this reason, the calculation of stress by measurements seem to be rather risky.

3) Mikiewicz T., Recovery in Mild Steel Treated with Aluminium,
Scientific Papers of Poznan Technical University, series: Mechanics, No 4, pp. 121-151, 1962 (in polish)

The removal of internal stresses by annealing at low temperature of not much ageing, mild steel treated with aluminium, is a matter of considerable importance industrially on account of its can be carried through on a large scale, taking advantage of the recovery phenomenon, what is readily shown in the present paper. However recovery in mild steel is carried out by a complicated connection with other processes, above all of ageing, and that is way especial attention is paid to slow cooling of steel, in order to avoid supersaturation and thermal stresses both: in making ready the stock for tests and in annealing after cold work.
An enlargement of research method exactness was a further object of the paper, particulary of radiographic estimate of the state of stresses. This was obtained by applying:

1. Rachinger's method of resolution of the doublet K _{1 2},
2. a calculate method of computing the huff-value broadness and considering the influence of line contours of microphotometric profile after the separation of the doublet constituents
3. the introduction of a new, additional informer of the stresses delta-b, defined as the difference of half-peak widths on both sides of the back-reflection pattern. This referred to diagrams obtained by the back-reflection technique without rotating films and test pieces, to stabilise measurement of parameters in the same direction. Test pieces were annealed below the temperature range of the recrystallization.

4) Karp J., Zapalska-Nowal K, The Application of X-Ray Radiography to Determine the Strain of the Structural Lattice of Cast Steel, Scientific Papers of Institute of Foundry in Cracow (Poland), No 2/66, p. 93-99, 1966 (in polish)

The aim of the paper was to present the possibilities of the application of X-ray structural analysis to the investigation of the degree of the cast steel lattice strain. The investigation was carried out on two cast steel test pieces subjected previously to function by a rotary-alternating motion. Using the method of back-reflection photography a radiogram of the strained surface was made first and then the consecutive subsurface layers were analysed while the test piece was dissolved electrolytically. The etching was finished when the diffractogram obtained gave a picture identical or approaching that of the unstrained surface. The assumed depth of the lattice strain which may in some way characterise the given material and make possible conclusions about future applications of the material was determined for both test pieces.

5) Kasprzak W., Theoretical Principles of Measurements Methods of Strain State and Derivative Values, Scientific Papers of Wroclaw Technical University, No 165, series: Mechanics, No XXI, p. I 51, 1967 (in polish)

A method of the planning of strain state measurements in structural components, constructions of their models, is presented in this paper. The adopted method makes it possible to obtain by means of approximation correspondingly transformed results of measurements for the determination of stresses s_xx, s_yy, s_xy, fulfilling the dependences:

where: F - Aire's function, determined by means of a measurement The components of stress state may be expressed additionally as the functions of outside loads, and the sizes of a structural component. As it shown below, it is possible too, to determine the values of outside loads by means by experimental investigations, at the same time, there is a possibility to estimate the systematic measuring error of the method.
In the next part of the paper, there have been given the opinions of the author concerning the conditions which the size of area on which the measuring of strain is being made, has to fulfill. The result of these considerations was that 1> n_o d, where: n_o - limiting quantity of grains (in the paper the approximate method of no calculation was given), d - mean size of crystallite grain.
In the concluding part of the paper, the author deals with X-ray radiographic measurements of stress state, coming to the following conclusions:

1. the methods of interpretation of strain measurements by means of X-rays, given by Ageev [Ageev V A, Zumal Techniceskoj Fiziki, 1958, v. XXV111, No 11, p. 2515] and Glocker [Glocker R., Verfahren und Einrichtungen zur röntgenographischen Spannungsmessung, Handbuch der Werkstoffprüfung, Springer Verlag, Berlin, 1958] assume the continuous structure of tested material. Such an assumption is contradictory to the physical principles of measuring. And for this reason, the calculation of stress by means of such measurements seem to be rather risky;
2. it is possible to measure the strain by means of X-rays within the limit of one grain.

6) Hebda M., Selected Methods of Experimental Analysis of Internal Stresses in the Surface Layer, Scientific Bulletins of the Academy of Mining and Metallurgy, No 183, Series: Electrification and Mechanisation in Mining and Metallurgy, Bulletin 22, p. 1-129, Cracow 1967 (in polish)

A diagrammatic representation of zonal structure of the top layer has been made in this paper. Reasond have been given for the existence of a general interdependence between the quality of machine elements and the condition of surface layer. A suggestion has been made about the determination of the condition of surface layer by a dependence comprising the essential parameters of its structure.
It has been shown that internal stresses are one of the main factors determining the condition of surface.
In connection with this analysis three methods have been selected or adapted, viz., a Weissman-Phillips [Waisman J. W., Phillips A., Simplified measurement of residual stress, Exp. Mech. Soc. Proc., 1952], a X-ray and an Oppel method [Oppel R., Die zerstörungsfreie Ermittlung von Eigen-Spannungen mittels Härtemessung an der Oberfläche von metallischen Bauteil, Materialprüfung, Bd B, H. 1, S. 6.10, 1964] of testing the value, distribution, gradient and depth of internal stresses in the surface layer.
Two series of specimens have been made of steel 10, and annealed. Following this one surface of each specimen has been ground. The depth of grinding was 0.04 mm in the first series of specimens and 0.08 mm m the second series. The internal stresses in the top layer caused by grinding have been tested by the three above named methods, and the results obtained have been shown in this work. The gradient of internal stresses in the surface layer was tested by the method of venous depths of penetration of X-rays into the material of the surface layer (various value of mass absorption factor, various value of geometrical factor). On the basis of oblique photographs the values of components of the flat condition of stresses have been examined. Moreover, a use has been made of a X-ray microtube to identify the local condition of internal stresses in the surface layer of metal.
In the Oppel method the load applied to the Knoop indenter was changed (the depth of penetration of the indenter into the surface layer). In this way the gradient of 1st type internal stresses in the surface layer was examined.
In the ending of the work a comparison has been made between the numerical results of testing the values, distribution, gradient and the depth of internal stresses in the surface layer, by the aforesaid three methods.
On the basis of the analysis of test results an estimate of each method for testing the internal stresses in the top layer has been made. The most essential elements of the work being discussed are contained m the conclusions.

7) Senczyk D., The Analytical Methods of a Precise Defining of the Angular Diffraction Line Position in the Methods of Very Accurate Macrostresses and Lattice Constants Measurements, Scientific Papers of Poznan Technical University, No 63, Series: Mechanics, No 10, p 45 - 68, 1969 (in polish)

This paper is devoted to the analysis of the methods of defining the angular diffraction line position in consequence of the 1st kind very precise macrostresses and lattice constants measurements. Five newly worked out methods have been described, enabling such definitions based on: parabolic approximation, the condition of the smallest sum of squares, the appointing curvilinear regression with the help of orthogonal multinomials, the condition of the tangent parallelism to the diffraction line in the maximum point of diffraction line and the background line, the condition of curvature maximum or the minimum of the curvature radius.
The correcting way of results on the account of the Lorentz's, polarization and absorption factors have been given. The mathematical analysis of the problems above made the introduction of formulas possible, allowing the quick and precise defining of lattice constants and of the macrostresses with the statistics grasp of these problems.

8) Senczyk D., The Simultanous Defining Method of the 1st and 2nd Kind of Stress and the Mosaic Blocks Parameters Defining Based on the Angular Intensity Distribution of Diffraction Line Analysis, Scientific Papers of Institut of Poznan Technical University, No 63, Series: Mechanics, No 10, p. 69-81, 1969 (in polish)

A new method of the line profile K₁ separation from washed out doublet K₁₂, based on the harmonic analysis of the angular intensity distribution of an inseparable doublet. The mathematical analysis of this problem enabled an introduction of simple formulas directly binding the distribution coefficients into Fourier's series of K₁ diffraction lines with the inseparable distribution coefficients of the line doublet K₁₂. The worker out method of separating into components line doublet enables the simulations defining and unification of the defining method of the 1st and 2nd kind of stress, and mosaic block parameters based on the harmonic analysis of the angular intensity distribution of a diffraction line.

9) Sencyk D., Seeming Variation of Interplanar Distance of Broad Diffraction Line in Metals and Alloys X-Ray Analysis, Poznan Science Society, 1969 t. II zeszyt 1 s. 87-155

In many problems concerning crystallography and metal physics the knowledge of the exact value Bragg angles of diffraction lines in the phase being investigated is indispensable. Resulting from a nonhomogenity of a solid solution or dispersion of areas of coherent dissipation of X-ray radiation, or at last from microstress these lines are quite often considerably broad reflected. A similar event is encountered in the determination of stress by the method of oblique photographs. While the width of the diffraction line increases, the maximum of the line shifts always towards the component K₂. The measured value of Bragg's angle will differ frame the real one. In precise measurements of lattice constant a suitable correction has therefore to be introduced for this displacement. The discussion about this problem is just the aim of this work. A mathematical analysis of this problem performed for different functions (e. g. Gauss'function, Cauchy's function, function sin²kx/(kx)²) describing the distribution of the intensity of the diffraction line showed, that a seeming relative change of interplanar distance may be expressed by the equation:

where: x_m - maximum position of nonseparated doublet diffraction lines,
- distance inter doublet component.
This change results from a broad reflection and may be eliminated by the introduction of a suitable correction. It has been stated, that the effect of a seeming interplanar distance change depends virtually on the wave length of the radiation being used. The mathematical analysis of this problem allowed to draw curves enabling the introduction of a suitable correction

to the determined parameter value of the lattice (h, k, I - Miller indices). The phenomenon of seeming variation of interplanar distance of broad reflection in connection with defects of atomic layers in the crystal and Suzuki's atmospheres have been discussed as well. The application of the method worked out for corrective calculation of seeming variation of interplanar distance in the process of determining this distance and lattice constants leads in the effect to a diminution of mistakes in the determination of these magnitudes basing on reflection.

10) Senczyk D., Accuracy Analysis Determination of Interplanar Distance by Some Precision X-Ray Methods, Poznan Science Society, 1969 t. II zesyt 1 s. 50-86

In precise methods determination of lattice parameters several corrections are introduced which take into account the systematic mistakes in Bragg's angle determination. The accuracy of these methods will mostly depend on accidental mistakes, the most important of which is that of distance measurement between diffraction lines on the rentgenogram. The analysis of influence of this mistake-magnitude on the determination-accuracy of interplanar distance is the aim of this work. This problem has been analysed for several cameras and methods as follows: Debye's-Scherrer's-Hull's camera (Straumanis'-Jevins's method), flat camera (Sachs'-Weerts'method), Preston's camera, Seemann's-Bohlin's camera. In all methods, except that of Sachs-Weerts, it has been confirmed, that the mistake of determining the interplanar distance diminishes till zero with the increase of Bragg's angle to 90°. For the flat camera this mistake is described by the function having its maximum at = 70° and tending towards zero for -> 90° and -> 45°:

where:
D' - distance sample-film,
Dl - measurement accuracy of distance diffraction lines
- Bragg's angle of investigated substance,
_wz - Bragg's angle of standard.
The faculty of separation acquired by using different X-ray cameras has been analysed as well.

11) Pszonka A., Ziaja J., X-Ray Methods of Measurements of Stresses, Scientific Papers of Institut of Materials Science and Applied Mechanics of Wroclavv Technical University, No 8, Series: Studies and Research, No 6, pp 130, Wroclaw 1971 (in polish)

In this paper theoretical and experimental methods of examination of the state of strain and of stress on the grounds of shifts of the position of the diffraction lines of X-ray photographs and diffractograms are discussed. It has been assumed that the respective strains of the material are elastic strains, hence strains described by equations of the theory of elasticity.
Various methods of measurements are mentioned: beside the commonly known and applied theories of Sachs and Weerts or Glocker and Oswald the relatively newly elaborated so-called "Method sin²" is inserted, as well as also the most general theories of Aghieev and Kasprzak which are missing in other elaborations. It can be shown that the earlier elaborated methods are particular cases of the latter of the above mentioned theories of X-ray measurement of stresses.
A matter by no means trivial of the value of the material constants, occurring in the formulae of stress measurements, for the proper interpretation of the results of the measurements. Therefore there also is mentioned the method of determination of the material constants of polycrystal on the ground of the knowledge of these constants for the monocrystals, which gives fair approximation of the material constants for selected regions of the polycrystal.
Measurements of the position of diffraction lines are performed either with the plate or with the diffractometric technique. Both theses measuring techniques have been elaborated separately, out of regard for their specific features. In the chapter about the photographic technique, beside a series of cameras the description of which can be found in earlier general elaborations, two new cameras for special purposes have been inserted: a plano-cylindrical camera and the plano-conical camera Szanto.
The application of diffractometers made it possible to extended measurements of stresses to substances which give broadened X-ray diffraction lines and which, therefore, cannot be examined with the plate technique. This fact imposed the necessity to take into consideration additional factors, having effect on the change of the shape of the profile of the lines. These factors are connected with the geometry of the oblique exposure of the examined surface. The manner how to effect correction of the shape of the diffraction line has been precise discussed, and the values of the correction factors C' = LPA have been tabulated, for the convenience of those, who make such measurements (L - Lotrentz factor, P - polarization factor, A - absorption factor).
Beside the above information, a number of supplementary information's has been mentioned which have effect on the result of a measurement of stresses and on its interpretation there also has been mentioned a side application of this method of measuring stresses: change of stresses inside the specimen, hardness measurement, effect of plasctic strains etc.
For information, certain numerical values, obtained by the different authors, are indicated. Because the aim this work was to compile the basic knowledge about the problem contained in the title, details must be found in the original works. Therefore, the bibliographic part for the different problems has been treated as comprehensively as possible in order to allow the reader to get quickly to the sources of information.

12) Kasprzak W., Pszonka A., Ziaja J., Determination of The State of Strain in Single Crystalites of the Regular System with the Help of X-Rays, Scientific Papers of Institut of Materials Science and Applied Mechanics of Wroclaw Technical University, No 5, Series: Studies and Research, No 3, pp. 27 36, Wroclaw 1971(in polish)

In this paper, a description and methods of the measurement of the state of strain in since crystallites of a polycrystal, belonging to the regular system, are given. Strain measurement is performed after a selection of crystal grains and after the determination of their spatial orientations in relation to the system connected with the examined specimen, thus of the orientation of system X'_j in relation to X_j (X_j - system (external) connected with the specimen X'_j - system connected with crystallographic axes in investigated crystallit, X''_j - system of principal strains in investigated crystallit.

13) Pszonka A., Ziaja J., Proposal of Measuring The State of Strain in a Single Crystallite of a Polycrystal Test Piece With The Diffractometric Method, Scientific Papers of Institut of Materials Science and Applied Mechanics of Wroclaw Technical University, No 5, Series: Studies and Research, No 3, pp. 37-46, Wroclaw 1971(in polish)

In this paper, the description of a new method of diffractiometric measurement of the state of strain within the limits of one crystallite of a polycrystal body is given. The analytic elaboration was made for crystallites of the regular system. but the described method is valid also for crystallites of other crystallographic systems. A comparison of the potentialities of the described techniques and of a method of a similar measurement in [Kasprzak W., Pszonka A. Ziaja J., Scientific Papers of Instiut of Materials Science and Applied Mechanics of Wroclaw Technical University. Series: Studies and Research, No 5, Wroclaw 1970] with that described in this paper as a new method shows a significant superiority of the new method which consists in a simplification of the experimental technique and in shortening the time necessary for the performance of the experiment, where the accuracy of measurement is increased. For the purpose of determining the changes of six interplane distances ⁱ_hkl for the selected planes (h_ik_il_i) which are necessary for the determination of the external system X_j (connected with the specimen). two angles are sufficient: one of the diffractometer. the other of the rotation of the specimen.

14) Pszonka A., Ziaja J., Quick Determination of the X-Ray Peak at Stress Measurements, Scientific Papers of Institut of Materials Science and Applied Mechanics of Wroclaw Technical University, No 5, Series: Studies and Research, No 3, pp. 47 · 52, Wroclaw 1971(in polish)

A new method of determining the position of the vertex of a X-ray peak which can be applied particularly for diffraction lines strongly broadened, which we meet while testing stresses in hard steels is described. To the recorded peak. a curve gauge with traced reference curves is applied. The central situation of the intersections with the diffraction line of the reference curve, which is at a level of about 85% of the intensity in the X-ray peak, indicates the position of the vertex of the line. This method considerable shortens the time of determining the stress in the specimen at application of the X-ray technique.

15) Senczyk D., X-Ray Laboratory, Poznan University of Technology, Poznari, ed. I 1974, ed. 2 - 1982, 425 pages,

16) Ziaja J.. X-Ray Diffraction Methods of Determining the Real Structure Parameters of a Polycrystalline Material. Scientific Papers of Institut of Matenals Science and Applied Mechanics of Wroclaw Technical University, No 27, Series: Monographs, No 8, pp. 85, Wroclaw 1975 (in polish)

A critical review was carried out concerned with the X-ray diffraction methods applied to determine parameters describing the structure and deformation in polycrystalline materials, on the basis of their phenomenological and physical models. Principles of the formation of diffraction lines are briefly discussed. Physical and geometrical factors exerting an influence on their distribution were considered as well. For a phenomenological model, methods of determining the lattice defects and the subgrain dimensions are given in terms of an approximation and harmonic analysis as well as by means of moments variance method included. Methods of determining the deformation of the first and second order are discussed too. Special attention was paid to a preliminary analysis of the diffraction line. Problems dealing with the estimation of the background intensity, the distribution of the Ka doublet and the position of the diffraction line were also considered.
There is discussed, in this paper, the influence of real structure defects on the position and shape of the diffraction line in the physical model of the polycrystalline material. Special emphasis was put on the point defects. the dislocation structure (like: screw dislocation. edge dislocation. and dislocation loops), stacking faults, twins and microcracks. With the aim to illustrate the fundamentals of the diffraction analysis, the kinematic theory of X-ray diffraction methods was discussed.
All the X-ray diffraction methods considered in this paper are based on extensive literature studies.

17) Frydman S., X-Ray Measurements of Elastic Constants un - and -Brasses, Scientific Papers of Institute of Materials Science and Applied Mechanics of Wroclaw Technical University, No 24. Series: Studies and Research, No 15, pp. 59 69, Wroclaw 1975 (in polish)

The basic formulae of X-ray stress measurements are summarised. The elastic constants were determined using the sin² method. Experimental procedures and the elastic constants values obtained by the X-ray method for single-phase - and -brasses are reported. The values of the elastic constants obtained by means of the X-ray method are compared with those measured by mechanical ways. The X-ray elastic constants were used to determine the state of stress in and -phases of single- and two-phase brasses. Experimental results: a) for -brasses in [331] direction: s = -3.58*10¹² Pa^-1, 1/2s₂ = 14.8 10*¹² Pa^-1. b) for -brasses in [222] direction: s₁ = -3.58 *10¹² Pa^-1. 1/2s₂ = 17.8*10¹² Pa^-1.

18) Senczyk D., The Analysis of Error Sources and Experimental Determination of Precision in Measurements of Macrostresses by X-Ray Methods for Chosen Polycrystalline Materials, Poznan University of Technology, series: Dissertations, No 110, pp 171, Poznan 1980 (in polish)

The aims of the paper are: 1) an attempt to systematise all possible sources of error in macrostresses measurements by X-ray methods. 2) systematic analysis of the effects and factors influencing on the precision of macrostresses measurements by these methods, performed on the grounds of both literature and our experimental data, 3) determination of the practically reached precision in macrostresses measurements by the commonly used sin² method, 4) a comparison between the X-ray method with other methods of macrostresses measurements, using our own devices to deform samples in counter goniometer.
The attempt to systematise sources of errors in macrostresses measurement by X-ray methods is performed both for photographic and counter methods. The errors of these measurements are connected with physical effects and factors, with the equipment employed in measurements, the sample studied and the employed method and technique of measurement. All effects and factors considered are listed in section 4.
A general method of investigating venous factors influences on macrostresses measurements by X-ray methods is also described. It is a method general enough to enable to study not only the influence of various factors but also may be applied to study various stresses states with analysing the influence of only one given factor, neglecting all others. The usefulness of the method described is proved by its employment described in the paper.
Systematic analyses is performed of venous factors influence on macrostresses measurements by the following X-ray methods: sin² method of measuring principal stresses, diffractiometric method, the methods of Glocker-Hesss-Schaaber and Gisen-Glocker-Osswald concerning the measurement of stresses in a given direction and the method of Sachs-Weens concerning the measurement of the sum of principal stresses. The synthesis presented covers both literature data and our theoretical results. The analysis performed indicates factors which should be included in macrostresses measurements and those which can be neglected.
The further part of the paper is aimed to determine the practically reached precision in macrostresses measurements by the sin² method for the polycrystalline materials: Armco iron, constructional steels: 15, 25, 45, 45H, 35HM, bearing steel LH15, tool steel NC7VL (under Polish Standards), in the annealed state and in the state tempered after hardening. Flat samples of these materials were deformed (pure bending or traction) directly in a counter goniometer by the specially prepared devices. The results of macrostresses measurements were statistically analised with the accepted upper limit of an absolute error equal to three standard deviation values.
The studies performed proved also that the precision of the macrostresses measurements by X-ray methods is constant through a long time.
Literature does not provide any accuracy solution as to the problem of counting the elasticity constants s, and 52 for polycrystalline materials and also does not present any values of them for the materials studied in our work. Therefore our paper presents the results of their measurements by X-ray methods for the materials studied. The following pan of the paper is concerned with a comparison between the X-ray method of macrostresses measurements and the resistance strain gauge and the mechanical method based on deflection of flat samples. The linear correlation between the stresses values obtained by all those methods is proved to be univocal and essential. Then, the project was proposed to standardise the methodology of measurements of macrostresses, microstresses and some other quantities characterising the mosaic blocks based on the harmonic analysis of the angular distribution of the diffraction line intensity.
Summarising the results of the paper we find that the studies performed proved the X-ray methods to be advantageous in macrostresses measurements and showed that the results obtained with it are comparable with those obtained by other methods macrostresses measurements.

19) Sencyk D., X-Ray Methods and Technics for Materials Structure Investigations, Poznan University of Technology, Poznan, 1984, 378 pages

20) Senczyk D., Macrostress Measurements in polycrystalline Materials by X-Ray Methods, Poznan University of Technology, series Dissertations, No 194. pp 145, Poznan 1988 (in polish)

This work consists of seven parts. In the first part being the introduction to problems considering in this work the proposition, the purpose of the work and research tasks are submitted. Then types, classification and methods of internal stresses measurements are described as well as elements of X-ray methods and technics of macrostresses measurements.
The part two contains an analysis of different effects and factors that influence on accuracy of macrostresses measurement by different X-ray methods. In introduction to this chapter a trial of systematisation of errors sources due to physical effects and factors, a type of apparatus used in investigation, a sample investigated as well as investigation method and measurement technics in macrostresses measurement by X-ray methods is performed.
In the third part results of elastic constants measurements for selected polycrystalline materials and two, necessary in these measurements, self-construction devices for direct samples strain in a goniometer of X-ray diffractometer are described. Detailed description of a procedure of experimental data analysis in the case of elastic constants measurements of polycrystalline materials by X-ray method is also shown as well as selection principles of X-ray diffractometer optimum working conditions illustrated by proper examples. The part four concerns determination of practically obtainable precision and accuracy of macrostresses measurements by sin² method as well as the time stability of these quantities for materials selected.
In the part five an analysis and investigations concerning others except precision and accuracy, estimation and selection criterion of X-ray macrostresses measurement methods in polycrystalline materials are described. The following criterion are reckoned among them: sensitivity of these methods, stress detectability, reproductibility and pepeatability of measurements as well as effciency and velocity of X-ray methods of macrostresses measurements. Theoretical analysis and experimental investigations have allowed to confirm a rightness of some measurement conditions used as yet only intuitively and to obtain several new conclusions indicating on possibility of increase or ensure of a determined accuracy for macrostress measurement by X-ray methods. This analysis is the first and original trial of solution of this problem. In the part six a comparison of X-ray and electric resistance wire strain gauge as well as mechanical, based on deflection measurement of flat specimens, methods of macrostress measurements are done. These investigations have indicated on synonimity and substantial of linear correlation between stress values determined by X-ray and the above mentioned two method. Comparative investigations performed in this work are in a good agreement with the literature data quoted.
The part seven contains four practical examples illustrating the selection of experimental conditions for macrostresses measurement in different units using X-ray methods. Self-construction devices enabling large and heavy units measurement with the aid of conventional X-ray diffractometers are also described. It would be impossible to lead measurements without these devices. In all examples conclusions resulting from theoretical analysis and experimental results performed previously were used.
Finally the summarizion of results obtained in this work was done. It indicates that the purpose of the work and research tasks are fully realised and the proposition of the work is proved.

21) Senczyk D., X-Ray Diffractometry in Stress States Investigations and Elastic Properties of Polycrystalline Materials, Poznan University of Technology, pp 283, Poznan 1995 (in polish)

22) Senczyk D., Internal Stresses. Introduction to generation, control and application, Poznan University of Technology, pp. 311, Poznan 1996 (in polish)

Acknowledgment

This research was supported by Poznan University of Technology (Poland) under Grant No. 24-217/DS/97.