Haruo Fujiwara

X-ray residual stress measurement of laminated coating layers produced by plasma spraying

Abstract The present paper describes residual stress in laminated layers deposited by thermal spraying on a low carbon steel substrate. Laminated layers were made of Al 2 O 3 −NiCr or Al 2 O 3 −NiAl with various combinations of mixing ratios. X-ray diffraction was used to measure residual stress in the outermost surface layer. The results of finite-element method (FEM) thermal stress analysis were compared with the experimental results of X-ray measurements. From the X-ray stress measurements, tensile residual stress (100–300 MPa) was measured in the as-coated surface layers of all specimens. The effect of annealing on residual stress variation was also examined. In the case of the Al 2 O 3 (100%) layer of the Al 2 O 3 −NiCr system, residual stress of surface layers was not greatly affected by the method of lamination and did not change significantly upon annealing. In contrast, in the layer with mixed Al 2 O 3 and NiAl, residual stress in the as-coated layer was influenced by the mixing ratio of Al 2 O 3 and NiAl. Furthermore, residual stresses were gradually reduced in both the Al 2 O 3 and Ni phase following annealing. FEM calculation revealed that large compressive residual stress (about —2 GPa) was produced in the 100% Al 2 O 3 layer after a full annealing treatment. The value of residual stress depends on the difference between the thermal expansion coefficients of the laminated layers and the substrate. This result was exactly opposite to the experimental results for the fully annealed Al 2 O 3 −NiCr system. However, residual stresses in the mixed layer (Al 2 O 3 −NiAl) depended on the mixing ration of Al 2 O 3 and NiAl. This agrees qualitatively with the experimental results.

An evaluation of mass screening for breast cancer

In Tokushima Prefecture, Japan, 41,922 women (26,669 in actual number) were subjected to mass screening with physical examination from 1970–1977. In 42 including 10 of so-called “interval cancer”, breast cancer was detected. Those with breast cancer detected by mass screening were in the earlier stage of the discase as compared to those diagnosed through regular medical care at our out-patient clinic during the same period. Procedures such as inspection and palpation are readily carried out and early occurrences of breast cancer can be detected.

Residual Microstress Development in Steels After Tensile Deformation

Residual stress development in steels containing spherical cementite particles was investigated with a function of plastic strain and a volume fraction of cementite phase. Residual microstresses in both the matrix and the cementite phase were measured by means of X-ray diffraction. The results were compared with analytical predictions by the theory of micromechanics and the finite element method.

Influence of Microstress on X-ray Residual Stress Analysis

ABSTRACT The criterion of triaxiality in X-ray residual stress analysis is studied in relation to the wavelength of microstress distribution and relaxation of relevant stress components in a near-surface layer. The relaxation of tessellated stress in spherical second-phase particles near the surface layer was analyzed, and the experimental results for M6C carbide particles in a high-speed steel was compared with the theoretical prediction. Examples of residual micro-stress measurement are discussed for ground and stretched specimens of a two-phase system.

Evaluation of Thermal Stresses in Continuous Alumina Fiber-Reinforced Aluminum Composites by X-ray Stress Measurement

ABSTRACT An X-ray diffraction technique was applied to determine both the matrix and fiber stresses during thermal cycling processes for a continuous fiber FP (α-alumina)/A1 composite as well as for a continuous γ-alumina/A1 composite. In-situ X-ray stress measurements at all temperatures throughout the test range were automatically carried out in a vacuum furnace mounted on a computer-controlled diffractometer, which had been improved in such a fashion that the conventional sin 2 Ψ method could be used. It was confirmed that, when the composite systems were subjected to a change in temperature, thermal stresses were induced in the matrix and fibers because of the mismatch in thermal expansion coefficients between the two phases, and that the resultant stresses in the matrix and fibers balanced each other in the composites. Furthermore, it was proved by the X-ray method that, during the cooling process of the composite, the matrix was plastically deformed in tension, and during heating, in compression. The Al matrices of the two composite systems were observed to deform in a similar manner during the thermal cycle. The X-ray technique is shown to be useful for evaluating the thermal stresses as a function of the temperature of a composite.

X-Ray Stress Measurement of Si3N4 Ceramics

X-ray elastic constants of sintered, hot-pressed and HIP’ed Si3N4 ceramics were determined for various diffraction lines with CrKα radiation. With its result, X-ray stress measuring method was applied to investigate the residual stress distribution in a ground surface layer and the thermal stability of residual stresses. The residual stress was compressive over the entire ground surface layer, and the depth in which the residual stress existed was not greater than 20 μm even in the case of heavy grinding condition. Both macro and micro residual stresses are stable under the temperature less than 1000K.

Redistribution of Residual Stresses and Dimensional Change

The present work investigates the relation between the residual stress alteration and the dimensional change of the body. The specimens used in this investigation were a circular plate and a rectangular plate. Both surfaces were covered with thick jigs so as to prevent a heat flow through the surface and then quenched into water from 700°C. By this quenching process a plane residual stress state was produced; compressive residual stress in the outer region and tensile in the inner region. The outer material of the circular plate where the residual stress state was axially symmetric was uniformly removed by electrical discharge machining (EDM). The residual stress distribution changed from the original one and the remained circular plate shrank uniformly. The rectangular plate had initially uniaxial residual stresses varying along the width of the plate. The disk which was cut out from the center of this plate by EDM became elliptic shape even if a cylindrical discharge electrode was used. Simultaneously, the residual stresses in the disk were rearranged greatly in a biaxial state. The shape of bored hole also became an ellipse but the direction of stretch and shrinkage were opposite to that of the disk. The finite element method (FEM) was applied to analyse such alteration of residual stress state as well as shape and dimension of the plates. The results of FEM analysis agreed well with the experimental data.

The X-Ray Measurement of Residual Stress in Stainless Steel Used as Clothing Metal

A stainless steel clad plate, consisting of a stainless steel plate and an other-kind-of-steel plate combined together by rolling, explosion or other technique, becomes equipped with both the properties of the clothing metal and of the base metal. Since reinforcing the base metal by clothing it with stainless steel to raise its resistance against corrosion and pressure has come to be in vogue in recent years for various purposes, the problems regarding the clothing metal have begun to attract attention, particularly with respect to the residual stress on its surface and the internal distribution of stress in it.In the present paper is presented the result of experiment made concerning the residual stress in the stainless steel clad plate which had been subjected to hot rolling in the clothing. Two specimens have been used, the SS41 base metal clad with the SUS28 stainless steel plate (RA material), and the SB42 base metal clad with the SUS38 stainless steel plate (RF material).The residual stress released by cutting the steel plates to clothe the base metal of RA and RF materials into small blocks was found to be within the range of ±6kg/mm2. The X-ray measurement of stress on the surface of the clothing SUS28 stainless steel plate and of stress distribution in its depth revealed that ca. 20kg/mm2 of compressive residual stress was generated in it, and that ca. 15kg/mm2 of tensile residual stress was generated in the SS41 base metal.This difference is considered to be due to the difference between SUS28 and SS41 in thermal expansion coefficient, and it is considered that there was plastic deformation of SUS28 while it was subjected to cooling in air. On the other hand SUS38 and SB42 were approximately equal in coefficient value, and so no residual stress was detected in RF material.From the result of measurement of the residual stress distributed in the plates and of the width of the diffraction line in them, it is supposed that the combination of the steel plates by rolled clothing is effected within very thin scopes of their respective layers.