Estimation of the Fatigue Strength of Iron Castings by X-Ray Stress Measurement Technique

Two kinds of electrodeposited copper foils (thickness is 8 and 20 μm) were loaded statically, and the deformation behavior was observed. In-situ X-ray stress measurement was carried out under tensile loading. Fatigue tests were also conducted to observe the effect of the thickness on the fatigue strength. Change in the line broadening with stress cycles was observed to evaluate the fatigue damage. The tensile strength of 8 μm foil was higher than that of 20 μm foil. When the foils were loaded within elastic region, the stress measured by the X-ray method agreed with applied stress. When the plastic deformation occurred, difference between the measured stress and the applied stress became large. The difference of 20 μm foil was larger than that of 8 μm foil. Fatigue strength of 8 μm foil was also higher than that of 20 μm foil. The value of the full width at half maximum, FWHM, increased rapidly at the first cycle, and then the value became nearly constant. Just before fracture, the value increased again. The change in FWHM corresponded to the change in the accumulated ratchet strain.

Download Full-text

Stress Estimation of Titanium Casting Alloy by X-Ray Measurement Technique of Single Crystal

Materials Science Forum ◽

10.4028/www.scientific.net/msf.652.143 ◽

2010 ◽

Vol 652 ◽

pp. 143-148

Author(s):

Nishida Masayuki ◽

Hanabusa Takao ◽

Ayumi Shiro ◽

Tatsuya Matsue

Keyword(s):

Residual Stress ◽

Single Crystal ◽

Measurement Technique ◽

Stress Measurement ◽

Position Effect ◽

Casting Alloy ◽

Diffraction Profile ◽

Titanium Casting ◽

X Ray ◽

Crystal Grains

Residual stresses in titanium casting alloy were estimated by X-ray stress measurement technique. There are two problems in the condition of X-ray stress measurement. Firstly, the titanium casting alloy has the large crystal grains. These coarse grains were generated under solidification processes and those sizes are approximately 2 millimeter in this study. These coarse crystal grains interfere with an accurate stress measurement due to the unstable diffraction profile [1]. This is because the existence of a sufficient number of isotropic crystal grains in the X-ray irradiation area are based on the X-ray diffraction theory. In this study, the stress measurement technique of single crystal materials was adopted for the solution of this fundamental problem [2, 3]. Because the coarse crystal grain was treated as a single crystal, the high intensity diffraction profiles were observed from a certain direction with investigations of crystal orientation. The problem with the coarse crystal grain in titanium casting alloy were cleaned up by the employment of the single crystal measurement technique. Secondly, the results from this study show that the position of crystal grain within the X-ray irradiation area greatly influenced the residual stress values. Therefore, in the present paper the erasing method of this position effect was tried and discussed [4]. Finally, the improvement of the accuracy of this method for the residual stress measurement in titanium casting alloy under the several bending stresses was confirmed. These results show that the erasing method in this study is an effective correction method.

Download Full-text

X-Ray Study on Deformation and Fracture of Solid. Residual Stress Measurement of Ground Composite Materials Prepared by Powder Metallurgy.

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.50.713 ◽

2001 ◽

Vol 50 (7) ◽

pp. 713-718

Author(s):

Shigeki TAKAGO ◽

Toshihiko SASAKI ◽

Yukio HIROSE

Keyword(s):

Residual Stress ◽

Composite Materials ◽

Powder Metallurgy ◽

Stress Measurement ◽

Residual Stress Measurement ◽

X Ray ◽

Deformation And Fracture

Download Full-text

Statistical analysis of the reproducibility of residual stress measurements in cold extruded parts

Archive of Applied Mechanics ◽

10.1007/s00419-021-01953-x ◽

2021 ◽

Author(s):

Fabian Jaeger ◽

Alessandro Franceschi ◽

Holger Hoche ◽

Peter Groche ◽

Matthias Oechsner

Keyword(s):

Residual Stress ◽

Statistical Analysis ◽

Stress Measurement ◽

Industrial Applications ◽

Cold Extrusion ◽

X Ray Diffraction ◽

Forming Process ◽

X Ray ◽

Stress States ◽

Key Aspects

AbstractCold extruded components are characterized by residual stresses, which originate from the experienced manufacturing process. For industrial applications, reproducibility and homogeneity of the final components are key aspects for an optimized quality control. Although striving to obtain identical deformation and surface conditions, fluctuation in the manufacturing parameters and contact shear conditions during the forming process may lead to variations of the spatial residual stress distribution in the final product. This could lead to a dependency of the residual stress measurement results on the relative axial and circumferential position on the sample. An attempt to examine this problem is made by the employment of design of experiments (DoE) methods. A statistical analysis of the residual stress results generated through X-Ray diffraction is performed. Additionally, the ability of cold extrusion processes to generate uniform stress states is analyzed on specimens of austenitic stainless steel 1.4404 and possible correlations with the pre-deformed condition are statistically examined. Moreover, the influence of the coating, consisting of oxalate and a MoS2 based lubricant, on the X-Ray diffraction measurements of the surface is investigated.

Download Full-text