Abstract Residual stresses (RS) in pipes welded by a fully automated friction welding process, called FRIEX, are investigated using the contour method (CM) and the X-ray diffraction method (XRD). Samples were produced using a self-developed equipment, which is based on the interaction between a consumable intermediate rotary ring and two stationary pipe sections, by varying the loading rate applied during the welding of API 5L B pipes with an API X65 ring. Mechanical and metallurgical properties were locally analyzed through metallography and microflat tensile tests. RS measured by XRD and CM showed comparable values; tensile zones were found in the pipe HAZ and compressive stresses were found in its adjacent areas. Tensile RS of approximately half the local yield strength of the components were also found, mostly on the internal surface, and their values decrease with increasing welding loads. Microflat tensile tests showed an increase in yield strength of pipe TMAZ and HAZ, with a clear influence of loading rates.

Resonant vibration residual stress relief (R-VSR) is an alternative method to post-weld heat treatments (PWHT) which is said to lead to less distortion and lower costs. The method of superposition of cyclic stresses and residual stresses, which can lead to localized yielding of the material, dislocation movement and subsequent stress relief. This article aims at investigating the efficiency of resonant vibration in the relief of residual stresses in welded joints of HSLA Domex700 steel sheets. Mechanical stress relief was compared to a common PWHT, and stress levels were then quantified through X-ray diffraction. Samples were also characterized by CTOD fracture toughness tests, fractographic analysis and tensile tests. Results indicate that the mechanical method was significantly less effective in relieving stresses in comparison with the PWHT, but led to apparent improvements in fracture toughness and in tensile tests. FWHM values indicated significant distortion for PWHT and less distortion for R-VSR.

In this work, the corrosion resistance of Inconel 625 coatings applied to AISI 4140 steel plates was evaluated. Coatings were produced by High Velocity Oxygen Fuel (HVOF) by use of two different equipment which use either kerosene (liquid) or propane (gas) as fuel. The resulting coatings were evaluated in two conditions: as-deposited and after a surface finishing process by grinding. Residual stress distributions in the coatings were characterized by X-ray diffraction and their morphology was verified through metallography and roughness measurements. Potentiodynamic polarization corrosion testing complemented their analysis. The results show a strong influence of the surface finishing process on the corrosion performance of the coatings.

Abstract The early detection of failures in structures is a subject of great interest in engineering; several of these techniques are linked with the elastic wave propagation, using guided waves is one of these alternatives. Several structures of interest in engineering are laminar arrangements; the wave propagation in this type of structures depends not only on the material properties, but also on the geometric parameters, such as the plate thickness. Tubular structures, pressure vessels, tanks and also parts of ships hulls could be considered laminar. The elastic wave propagation in laminar structures could be considered as a sum of modal shapes that have its wave length and frequencies defined. These mode families are characteristics of each structure and could be represented through the dispersion curves. The definition of these dispersion curves is of crucial importance to understand the propagation of guided waves in the structure studied. In the present work the dispersion curves were generated using three different methodologies, specific for metallic rectangular stems that compound the strengthening armor in flexible riser duct. Each approach presented in the analysis were carried out using standard finite element commercial packages and an experimental verification, as well. The premise is to present the topics in the simplest way, not only to understand how the dispersion curves are built but also how these curves must be interpreted.

The residual stress state of a mechanical component is an important factor in its production planning and in estimates of its lifecycle since it can be responsible for geometric distortions and degradation of fatigue properties. Therefore, the development of reliable methods for non-destructively quantifying these stresses remains in the interest of most manufacturing industries; Barkhausen magnetic noise measurements have been investigated in several applications and remains a viable option. However, its effective implementation has occurred mostly in components with simple geometries and insignificant microstructural gradients; even in these cases, successful industrial adoption of the method depends on previous calibration with samples that are often difficult and costly to prepare and validate. This work aims at investigating the capability of the method of characterizing the residual stress state in a simple but generally useful application: samples of hot-rolled steel sheets collected at two different stages of processing in an industrial mechanical conformation and heat treatment plant. In this analysis Barkhausen noise measurements were compared to X-ray diffraction results, and statistical analysis tools were used to correlate the results.

En el presente trabajo se describe el uso de un método no destructivo que combina las medidas de los parámetros micromagnéticos para cuantificar las tensiones durante los ensayos de tracción en alambres que componen la armadura estructural de risers flexibles. Este método consideró las técnicas de análisis armónico del campo magnético tangencial, análisis de ruido Barkhausen y el análisis del incremento de la permeabilidad, mediante el ensayo de tracción con carga controlada. Se utiliza la regresión lineal de multiparámetros para analizar los datos de cada técnica en forma individual y en conjunto, con el objetivo de correlacionar los valores conocidos de las cargas con los valores medidos en los ensayos realizados. Los resultados muestran una buena relación de los valores obtenidos mediante el método micromagnético y las cargas aplicadas a los cuerpos de prueba, demostrando la eficacia de la técnica en estas aplicaciones.

This paper reports the use of a non-destructive method that uses micromagnetic parameters to measure the stress in a wire during a tensile test in different load levels. This wires forms the structural armature of flexible risers. In this work was considered the parameters of the hysteresis curve based on Harmonic Analysis of the Tangential Magnetic Field Strength, Analysis of Barkhausen Noise Signals and the Analysis of Incremental Permeability Signals during a tensile test with load controlling. A linear regression was used to analyze the data and to correlate with the know data of applied load of the test machine. The results showed an excellent relation between the obtained measures of the micromagnetic parameters and the load applied in the sample, demonstrating a potentiality of the technique in this kind of applications.