X-Ray Stress Measurement by The Cos <i>α</i> Method Using Two-Dimensional Detector Part 2: Measurement Procedure and Applications

Abstract

The cos α method utilizes the whole Debye-Scherrer ring recorded on a two-dimensional detector taken by single exposure of X-rays to determine the normal and shear stresses. The simple optical system of the cos α method makes stress analyzers smaller, lighter, and handier to use for on-site measurements. Part 2 of this review describes several precautions of the measurement procedure to acquire accurate stress values in short time. The accuracy of the stress measurement of the cos α method has been confirmed to be equivalent to that of the sin 2 ψ method for various metals.

The cos<i>α</i> method for X-ray residual stress measurement using two-dimensional detector

“…Before determining the diffraction angle or strain, the measured profile of X-ray diffraction intensity is corrected by Lorenz polarization (LP) and absorption factors, and also by geometrical factor (Tanaka, 2017). The penetration depth of X-rays for the cos method is obtained as Tanaka, Mechanical Engineering Reviews, Vol.6, No.1 (2019) [DOI: 10.1299/mer.18-00378]…”

“…Various oscillation techniques are used to overcome this difficulty as described later. Figure 9 shows examples of D-S rings of Fe 211 taken from a carbon steel (JIS-S50C) using Cr-K radiation under normal incidence, where the full-width at half-maximum (FWHM) averaged around the whole circumference of rings is indicated in the caption of each figure (Tanaka, 2017(Tanaka, , 2018. In (a) for annealed surface steel, the variation of intensity around the circumference is large because of coarse grains.…”

“…9 Debye-Scherrer rings of various machined surfaces of carbon steel (S50C). FMHM is the full-width at half maximum averaged around the whole circumference of rings (Tanaka, 2017(Tanaka, , 2018.…”

“…With the use of a recent cos-based analyzer, the time required for one stress measurement is shortened to 60 s. The cosmethod is a genuinely Japanese original product in the sense that both software (fundamental theory) and hardware (IP and equipment) were born in Japan. In recent years, the method has attracted engineers as a new method of X-ray stress measurement abroad (Ling and Lee, 2015, Robinson and Redington, 2015, Ramitec-Rico et al, 2016 as well as in Japan (Tanaka, 2017), and applications of the method have been spreading to various engineering fields.…”

“…The stress on the polished surface of fine-particle bombarded (FPB) S50C steel plate was measured by the cos method under the application of four-point bending load (Tanaka, 2017). Diffraction of Fe 211 by Cr-K was used for stress measurement.…”