There are two directions of counter scanning when the stress measurement is made by means of X-rays. In the conventional method, the plane determined by the stress direction and the normal of the specimen is coincident with the plane determined by the direction of the incident X-ray and the direction of counter scanning. On the other hand, those two planes are perpendicular in the side inclination method, and In addition, X-ray beams must be irradiated from -η direction to the plane determined by the stress direction and the normal of the specimen. This side inclination method for stress measurement by means of X-rays is useful for measuring the stress in a complicated shape specimen.
When the measurement by the side inclination method is adopted with the apparatus used for the conventional method, however, it occurs quite often that the direction of X-ray beam has to be adjusted to coincident with the plane determined by the stress direction and the normal of the specimen. The value of stress calculated by the sin2Ψ method differs from the true value, depending upon the angle between the direction of stress and the principal axis.
In this study, the stress analysis is performed on the above incidental condition of X-ray beams and the values of stress are calculated numerically for several examples. Moreover, some results of the stress measurements are presented to prove the propriety of the present analysis.

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The stress state of large construction is very important and complex which is composed of residual stresses in their materials and produced stresses in their construction. Several trials have been carried out to evaluate the stresses in large constructions, but unsettled apparatus and approaching techniques prevented us from attaining the requirements of practical engineering objects.
To establish the measuring techniques and to develop some usable X-ray apparatus, the stress measurements were carried out on a large building block of a ship using X-ray method, as a trial. These experiences are reported here.

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In the previous paper, the applicability of the X-ray stress measurement for austenitic steel was examined on cold-rolled austenitic stainless steel plate, and as a result, the constant ψ method with the γ(311) diffraction of Cr Kβ radiation has been recommended. In this paper, the X-ray measurement based on the above results has been applied to the analysis of residual stress in an explosive austenitic stainless clad steel.
The results are summarized as follows:
(1) The error in the stress measurement is caused by various factors such as the constant K(-36.14±7.03kg/mm²/deg) used in the stress calculation, the scatter of the gradient in 2θ-sin²ψ diagram due to the statistical fluctuation of X-ray, and the broadening of half-value breadth as well as the superposition of diffraction intensity curves from γ(311) _CrKβ and α(211) _CrKα diffractions in the wavy bonded interface. However, the resultant stress patterns exhibit the next features.
(2) The biaxial residual stresses acting in perpendicular to each other show much the same patterns independently of explosive direction, being tensile in the surface layer of the stainless steel, highly tensile in the bonded zone, and compressive in the mild steel. These characteristics of the residual stress distributions can be roughly related to the peculiar mechanism of explosive bonding.
(3) The distributions of texture, microhardness and martensite in the cladding metal have peculiarities, and the microhardness and martensite distributions correspond with the plastic flow caused by the cladding.

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A new X-ray diffraction stress analyzer is described in this paper. It has the following features;
(1) Measurements can be switched between the conventional method or the side inclination method,
(2) the side inclination method has η a compensating mechanism, (3) the goniometer is oscillated at right angles to the plane on which the X-ray incident angle is changed during the side inclination method (x-axis oscillation).
X-axis oscillation and Y-axis oscillation (which means the oscillation around the same axis as rotation of Ψ) were experimentally compared for several coarse grained α-iron (211), of which sizes are 15∼300μ.
The results are summarized as follows. (1) The accuracy of the stress measurement for coarse grained specimens depends on the standard deviation of the half value width of the peak profile in every Ψ. (2) X-axis oscillation makes the standard deviation smaller than Y-axis oscillation and has a better effect in oscillation.

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It is well known that X-ray diffraction is advantageous when applied to metalic materials; it is very sensitive to changes in the crystalline structure.
In this paper, X-ray diffraction technique which is very important in studies on mechanical behavior of materials, is applied to the relations between the elastic, plastic deformation behavior and submacro- or micro-structure of tempered steels. Ni-Cr-Mo steel (SNCM8) and 0.16%C steel (S15C) are used in this experiment. The main results obtained are as follows.
(1) X-ray elastic constants S₂/2 and S₁ of (211), (200) diffraction planes are decreased with tempering temperature (250°-350°C), but that of (220) diffraction plane does not change over tested tempering temperature.
(2) Half value breadth of X-ray diffraction profile is changed by plastic deformation. At tempering temperature below 200°C, half value breadth of (110), (220), (200) and (211) diffraction planes decrease with less than 1% deformation. With over 2% plastic deformation, the half value breadth essentially remains constant. Its manner is the same as for martensite. On the other hand, at tempering temperature above 400°C, half value breadth of (110), (220), (200) and (211) diffraction planes increase with plastic deformation. Its manner is the same as for annealed metals. Between 250°C and 350°C of tempering temperature, however its behavior depends on the diffraction plane. Half value breadth of (200), (211) diffraction planes change in martensitic manner, but that of (110), (220) diffraction planes in annealed manner.

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Stress corrosion cracks which had occurred on a tank used for cloth dying were studied by means of X-ray diffraction and microscope observation. All cracks occurred in the neighborhood of welding beads on the cup side which was formed by drawing.
The cracked region was very strongly workhardened and it was detected by X-ray diffraction that very much martensite transformation (fcc→bcc) occurred. Residual stresses at this region were also measured by X-ray method, and it was found that most of them were compressive on the surface, but after removing the surface layer they turned out to be tensile.
Those cracks were observed on the surface, cross-section and fracture surface. Principal cracks initiated at corrosion pits, and propagated mostly on intergranular. Many subcracks could be observed and most of them propagated on transgranular. It seems that those crack initiation and growth were made by the tensile residual stresses which had occurred by welding heat and that they were much concerned with the phase change, since the corrosion was also accelerated by the martensite transformation.

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This paper presents some experimental data concerning the sintered steel joint brazed with Ag-Cu filler metal. The purpose of this study is to make clear the hardness distribution, structures of brazed joint, and relation between the mechanical strength of brazed joint and properties of sintered steel or brazing conditions.
The results obtained in this study are summarized as follows;
(1) The melted Ag-Cu filler metal penetrated into the pores of sintered steel. The penetration depth of BAg8-Cu-BAg8 filler metal was less than that with only BAg8 filler metal, resulting the excellent brazed joint.
(2) Both tensile and impact strengths of the brazed joint were degraded according to increase of sintered steel porosity.
(3) Both tensile and impact strengths of the specimen brazed with BAg8-Cu-BAg8 filler metal was greater than that brazed with only BAg8 filler metal. It seemed that penetration tendency of BAg8-Cu-BAg8 filler metal into the pores of sintered steel is less than that with only BAg8 filler metal.
(4) The tensile strength of the specimen with a narrow joint clearance (about 0.1mm) was greater than that with a wide joint clearance, its value being about 17.1kg/mm² (with BAg8-Cu-BAg8).
(5) The impact strength of the specimen with 0.2∼0.3mm joint clearance was the highest, its value being about 1.48kg-m/cm²(with BAg8-Cu-BAg8) and that with below 0.1mm joint clearance was extremely low.

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Ductile-brittle behavior of superplastic Zn-Al eutectoid-base alloys having various grain sizes was investigated by means of tensile and hardness tests over a temperature range from -196 to 30°C at various deformation rates. Fractography observations were also carried out.
A dependence of the ductile-brittle transition temperature (T_T) on grain size (l) and strain rate (ε) was discussed phenomenologically. The present data indicate that the T_T is given by the equations
T_T=(k_y-k_F)l^-1/2/Bσ_0F-ln(σ_0F/A')/B,
and
T_T=mln(ε)/B+ln(C'/F)/B
where k_y and k_F are Hall-Petch slopes, m is the rate sensitivity index, and B, σ_0F, A', C', F are constants. The T_T is in direct proportion to l^-1/2 since k_y is always greater than k_F for these alloys.
It is found that an addition of 0.43%Cu and 0.01%Mg to the Zn-Al eutectoid lowers the T_T by 35°K. The fracture mode is ductile intergranular failure due to nucleation and growth of cavities by grain-boundary sliding and dislocation pile-ups at temperatures above the T_T. In the vicinity of the transition temperature, the major fracture mode is coexistence of cleavage of basal plane in zinc-rich grains and the intergranular failures.

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The comprehension of the statistical fatigue property of structural steels is increasingly considered to be important as the basic data in designing with high reliability.
The authors had formerly reported the results of statistical fatigue tests performed on several structural alloys. The distribution characteristics in fatigue strength of the material were discussed by examining the distribution of the deviations in stress of individual test data from the median S-N curve. The present paper deals with heat-to-heat change of the statistical fatigue property analysed by the same method as before, for each 3 heats of 0.45%C carbon steel and 1%Cr-0.2% Mo-0.35%C low alloy steel. The effects of heat treatments and sharp notch were studied for 12 test conditions in total, each comprising more than 120 test specimens.
It was revealed that the Vickers hardness of heat treated materials coming from one heat obeyed the normal distribution law, and the fatigue strength of smooth specimens could be predicted by the same distribution law; while the fatigue strength of notched specimens showed an asymmetric distribution having a larger scatter in the weaker side and being approximated by Weibull's function. The variation coefficient of fatigue strength increases under the effect of notch, in varying degree depending upon heat treatment condition, probably reflecting microstructural differences at the fatigue crack tips. The heat-to-heat change in variation coefficient of fatigue strength for smooth specimens was explained by the variation of material's homogeneity, e. g. chemical composition, and by the substantial fatigue variation which increases with increasing fatigue strength of the material.

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The influences of cast skin, inner defects such as shrinkage, blowholes and mechanical notches on zero-tension fatigue strength of a 100kg/mm² 13 Cr stainless cast steel were investigated.
Three grades of cast steels, A, B and C, were produced by three kinds of casting procedures, varying the size and distribution of inner defects. The highest grade in the cast steels is C, followed by B and A.
Five types of specimens employed were unnotched specimens with or without cast skin (machined and no machined), circular notched specimens with or without cast skin, and Weibull notched specimen without cast skin. All five types of specimens made of A, three types of specimens without cast skin made of B, and an unnotched specimen without cast skin made of C were tested.
The results are summarized as follows.
(1) The fatigue limits of unnotched specimens were 21, 31 and 39kg/mm² for A, B and C, respectively. These values corresponded well to the respective elongation values. The ratio of the fatigue limit of C to a 13 Cr stainless steel, HUS 80, was 0.72.
(2) It was shown that the effects of cast skin, inner defects and mechanical notches on the fatigue strength can be illustrated by a schematic diagram in which the fatigue strength reduction factor is considered to be closely related to the highly stressed volume or suface area in a specimen.
(3) It was indicated that fatigue cracks started at inner defects in the case of unnotched specimens made of A and B. Thus, the estimation of their fatigue life was made using fracture mechanics, in which it was assumed that (a) the initial crack size equals the maximum inner defect size on the fracture surface, (b) the fatigue life is determined only from the crack propagation life. It was found that fracture mechanics is a useful tool to predict the fatigue life in such a cast steel.

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Two kinds of crankshafts for automotive engines were employed in the present study. One was the forged product of 0.55%C steel, quenched & tempered (crankshaft A), and the other was the normalized nodular iron casting (crankshaft B).
The states of stress under uniform bending were investigated on the crank-pin, web and journal along with the stress concentration on the fillet with the use of brittle coating and strain gages. The stress distributions on the middle section of the crank-pin and on the web section across the pin and journal fillets were, also, studied by photoelastic observation and Finite Element Method for a two dimensional model of crankshaft A.
Then, reversed plane bending fatigue tests were made on both kinds of crankshafts with a resonance type fatigue test device. Based on the results of stress analysis, the nominal stress on the web section across both fillets was selected as the significant stress of the crankshaft under bending. Reversed bending fatigue tests were also carried out with plain specimens of nodular iron taken from B crankshafts.
Finally, the S-N diagrams of the crankshafts expressed in terms of nominal stress of the web section were discussed in relation to the S-N diagrams of plain and notched specimens of the same material as the crankshafts.
The results obtained are as follows:
(1) The stress distribution on the crank-pin section seemed to be similar to that of a curved beam under bending. On the other hand, the stress distribution of the web section across the pin and journal fillets could be fundamentally regarded as simple bending of a straight beam.
(2) The stress concentration factor (the measured maximum stress over the nominal stress) of crankshaft A on the web section across both fillets was estimated to be about 2.9 at the journal fillet.
(3) Reversed bending fatigue fracture of crankshafts A and B occured actually through the web sections.
(4) The fatigue test results of crankshaft A expressed by the nominal stress of the web section mostly agreed with the evaluated S-N diagram of the crankshaft A based on the stress concentration factor of web section and the S-N relation of crankshaft material. The fatigue strength of the material of crankshaft A (quenched & tempered 0.55%C steel) was also evaluated from its hardness and microstructure.
(5) The S-N relation of crankshaft B under reversed bending was found to lie about a quarter nominal stress level lower than the S-N relation of crankshaft A. Reversed bending S-N relations of plain specimens of normalized nodular iron (material of crankshaft B) were also found a quarter stress level lower than the evaluated S-N relation of the material of crankshaft A.

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In recent years, considerable attention has been given to the life prediction of the member used at high temperatures. Especially, a number of data concerning interaction between fatigue and creep have been reported. It seems, however, that no study on life prediction have been published at high temperatures under random load. The present authors have undertaken the studies on life prediction by replacing random stress with superimposed stress pattern.
This report is concerned with the new life prediction method and fatigue-creep interaction. Experiments were conducted with SUS 304 stainless steel test pieces of 11.28mm diameter under axial loading at 600°C in air.
The results are summarized as follows;
(1) The effect of mean stress should not be evaluated solely by creep damage, but should be treated by taking fatigue damage into account also.
(2) The experimental life was one-fifth to five times as much as the predicted life which was calculated by the following equation;
N_es(ΣD_C+ΣD_f)=1
where ΣD_C=Σ∫^t0₀|σ|d^act/K_C……(creep damage)
ΣD_f=Σσ_a^afn/K_f……(fatigue damage)
σ_a=σ_a/{1-(σ_m/σ_B)^γ}^1/γ……(mean stress evaluation)
a_C, K_C; experimental constants for creep
a_f, K_f; experimental constants for fatigue

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The anisotropic fatigue behavior in 95% cold rolled pure aluminium is discussed in connection with the {111} pole figure, by means of optical microscopy and X-ray diffraction methods.
The results obtained are summarized as follows:
(1) The preferred orientation of 95% cold rolled pure aluminium is {112}-<111>+{110}-<112>, and the former is more dominant than the latter.
(2) Directions of the coarse and island-like slip bands correspond very well with those predicted from the {111} pole figure of rolled aluminium. Hence the anisotropic fatigue behavior can be qualitatively explained by the pole figure.
(3) The fatigue strength of rolled aluminium increases in the order of perpendicular, 45°and parallel direction. By regarding cold rolled material as an aggregate of single crystals having the same orientation with the rolling texture, the anisotropy in the fatigue strength is well accounted for.
(4) The texture of recovered material is more uniform or homogeneous than that of as-rolled one. The rolling texture does not make any change during fatigue process. The anisotropy in fatigue strength of recovered material owes to only the rolling texture, but that of as-rolled one is affected as well by the directional variation in residual stress.

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A new model of a growing fatigue crack is proposed based on the rigid-plastic-strip yielding approximation under the assumption that the pressure distribution existing between contacting crack faces behind the tip determines the value of stress intensity factor at the crack-tip opening point and also affects the amount of subsequent opening of crack faces. This model was verified in the experiment of fatigue crack propagation in two kinds of quenched-and-tempered carbon steel, where the behavior of opening and closure of crack faces was examined with an optical microscope. The amount of contact pressure was found to be a sole function of the mean value of the applied stress intensity factor.
Finally, the propagation rate of a fatigue crack was expressed as a function of the reduced range of stress intensity factor without respect to the values of stress ratio R.

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Notch tensile and fatigue tests have been made on 3% Si iron with various grain sizes. The plastic zone size associated with cleavage and fatigue crack propagation has been studied by a sensitive etching technique for detecting plastically deformed material. The mechanism of stable to unstable transition of fatigue crack propagation and the effects of grain size on the fracture toughness (K_c) and on the fatigue fracture toughness (K_fc) have been investigated.
The main conclusions are as follows.
(1) When the maximum stress intensity factor (K_max) is less than 0.7K_fc, the sizes of the slip band zone and the heavily deformed zone near a fatigue crack are proportional to the square of the variation of stress intensity factor (ΔK), while the plastic zone size associated with fatigue crack propagation is proportional to the square of K_max.
(2) The thickness of plastic zone formed near an unstable propagating crack does not depend on the stress intensity factor calculated by the compliance technique, but depends on the temperature and plate thickness.
(3) The process of fatigue fracture in a sharp notched specimen of low toughness material is divided into the following three cases:
(a) K_max<0.7K_fc: Stable crack propagation by fatigue.
(b) 0.7K_fc≤K_max<K_fc: A crack propagates stepwise by the interaction of fatigue and local cleavage, and the rate of crack propagation shows a large scatter. Micro-cleavagecracks are frequently observed ahead of a main crack on the plate surface as well as in the midsection.
(c) K_max≥K_fc: A crack propagates unstably.
(4) Fatigue fracture toughness is not influenced by the mean stress, and its dependence on grain size is smaller than that of K_c.

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In order to investigate the behavior of metals on impact fatigue, the new-type universal impact fatigue testing machine suitable for the tests under various conditions of stress or impact velocity was devised. Then, the three tests under different load conditions, the impact tensile tests, the impact tensile fatigue and non-impact push-pull fatigue tests, have been carried out on 0.21%C steel circular notched specimens at room temperature. To understand the surface features on the impact fatigue fracture, each fractured surfaces were observed by means of scanning electron microscope. The main results obtained were as follows:
(1) The four features, the lamella pattern on stage I fractured surface, the striation pattern, the dimple pattern and the cleavage pattern, were observed on both impact fatigue and non-impact fatigue fracture surface. The appearances of lamella and striation pattern on the impact fatigue fracture surface were clearer than that on the non-impact fatigue fracture surface at the same stress level.
(2) And also, the striations with chasms were observed on the former surface, but not on the latter one. It can be considered that the existence of this topography is the individual features on the impact fatigue fracture surface due to the variation of stress at crack tip.
(3) According to the increase of mean stress level, the area of stage I fractured surface decreased and the area of dimple pattern increased consequently. Also, the striations had a tendency to disappear with the increase of mean stress.

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With the intention of applying the X-ray diffraction technique to the failure analysis of metal components, X-ray observations were conducted on the surfaces of a super alloy Inconel X-750 fractured by impact, tensile, creep-rupture, low-cycle fatigue and fatigue crack propagation tests at high temperatures. The comparison of fracturing processes at the surface and the measurement of plastic zone size under the surface were attempted by measuring the tangential length S_T of diffraction arcs in X-ray patterns.
The results obtained are as follows:
(1) An X-ray pattern with larger S_T was obtained from a fracture surface having the larger ratio of dimple area in the cases of static loading and low-cycle fatigue.
(2) S_T had a correlation with the crack propagation rate and/or the repeated stress intensity factor in the case of high-cycle fatigue.
(3) The relation between the depth of the plastic zone ω and the repeated stress intensity factor ΔK was approximately expressed by the equation of
ω=0.15(ΔK/σ₀)²mm,
where σ₀ is 0.2% proof stress.

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