Optimization of Residual Stress Measurement Conditions for a 2D Method Using X-ray Diffraction and Its Application for Stainless Steel Treated by Laser Cavitation Peening

As the fatigue strength of metallic components may be affected by residual stress variation at small length scales, an evaluation method for studying residual stress at sub-mm scale is needed. The sin2ψ method using X-ray diffraction (XRD) is a common method to measure residual stress. However, this method has a lower limit on length scale. In the present study, a method using at a 2D XRD detector with ω-oscillation is proposed, and the measured residual stress obtained by the 2D method is compared to results obtained from the sin2ψ method and the slitting method. The results show that the 2D method can evaluate residual stress in areas with a diameter of 0.2 mm or less in a stainless steel with average grain size of 7 μm. The 2D method was further applied to assess residual stress in the stainless steel after treatment by laser cavitation peening (LCP). The diameter of the laser spot used for LCP was about 0.5 mm, and the stainless steel was treated with evenly spaced laser spots at 4 pulses/mm2. The 2D method revealed fluctuations of LCP-induced residual stress at sub-mm scale that are consistent with fluctuations in the height of the peened surface.

The Assessment of the Residual Stresses Influence on Generation of the Infringement in Shape-Complex Supporting Members

The aim of the paper is to assess the effect of residual stresses on the damage of the slide bearer. To quantify the residual stresses, the drilling method using SINT MTS 3000 drilling machine was chosen. The tensometric rosette application areas were determined based on the analysis of the results obtained by numerical modeling using the finite element method. Experimental measurement was performed on one unused slide bearer and on the other one, which during its present operation had completed about 9.106cycles. At the end of the paper, the analysis of the measured residual stress values in chosen locations is presented.

Residual Stresses in Ultrasonically Peened Fillet Welded Joints

Fatigue cracks mostly initiate at areas subjected to high tensile residual stress and stress concentration. Ultrasonic peening is a mechanical method to increase fatigue life by imparting compressive residual stress. In this study residual stresses are characterized in fillet welded ship structural steel plates with longitudinal attachments. As-welded, ultrasonically peened, and specimens peened then subjected to accelerated corrosion testing were measured. Residual stress characterization was performed by the contour method and neutron diffraction.

Simulating Residual Stress Profiles of Welds With Re-Heat Cracking in an Ex-Serviced AISI 316H Weld Header

In the current study, simulating residual stress distributions has been investigated for an AISI 316H austenitic stainless steels weld header and compared to actual measured residual stresses. These welds connect the outlet nozzle to the archetypal header 1B1/1 which was ex-serviced from Heysham power plant in UK. Finite element (FE) analyses of different load and boundary conditions have been performed to predict the optimum stress distribution around the cracking region to compare with available measured residual stress distributions in the literature. The FE predictions show that a remote displacement control tensile load on the nozzle with fixed vertical movement of cylinder can best fit the measured residual stress distribution. Hardness profile across the weld cross section indicates that the hardness gradually decease from HV 210 in weld metal to HV 160 in base metal, however, in the fusion away from 3 mm, the hardness were over HV 240. The facts indicate that the primary crack is likely to initiate at high hardness boundary and propagate in the direction of the highest principal stress regardless of the material hardness. Hypothesis of mechanism to the crack propagation is considered and proposals to predict damage and cracking in the header using FEM are presented.