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Porto Salvo, Portugal

Milovic L.,University of Belgrade | Vuherer T.,University of Maribor | Blacic I.,Military Technical Institute Belgrade | Vrhovac M.,Institute Soldadura e Qualidade ISQ | Stankovic M.,University of Belgrade
Materials and Design | Year: 2013

The subject of this paper is the microstructural and mechanical characterisation of regions of the heat-affected zone (HAZ) in steels containing 9-12% Cr that are used for operation at elevated temperatures. Tests were performed on regions in the HAZ, which was created by physical simulation using a thermal welding simulator. Half of the simulated samples (SSs) were tested at room temperature (RT) and at an operating temperature (OT) of 600. °C immediately after simulation/welding, while the rest of the simulated samples were tested at RT and at the OT after heat treatment following the welding, i.e., post-weld heat treatment (PWHT). In addition to the results from mechanical testing, the results from microstructural analysis using light microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are also presented. The manner in which PWHT contributes to the creep resistance of the HAZ in P91 steel is demonstrated. © 2012 Elsevier Ltd. Source


Liaptsis D.,Twi Ltd. | Nicholson P.I.,Twi Ltd. | Courinha J.A.,Institute Soldadura e Qualidade ISQ | Boynard C.A.,Institute Soldadura e Qualidade ISQ | Pinto M.,Institute Soldadura e Qualidade ISQ
7th International Conference on Condition Monitoring and Machinery Failure Prevention Technologies 2010, CM 2010/MFPT 2010 | Year: 2010

In the rail industry, manual Non Destructive Testing (NDT) is applied to wheelsets both during production and routinely at maintenance. As part of the development of a new manual NDT system combining complementary inspection techniques, a phased array ultrasonic inspection system for inspection of railway axles is being developed. This paper presents the initial study, which includes the phased array ultrasonic testing experimental setup and the initial results obtained after testing the system on railway axle calibration blocks. Two phased array probes, one with 64 elements and the other with 60 elements, each with differing excitation centre frequencies of 5 MHz and 7.5 MHz respectively, have been tested. The results have been compared to assess the probe's detection and sizing capabilities and to determine the sensitivity that can be achieved. In addition to practical experimentation, a series of modelling studies were undertaken using CIVA ultrasonic modelling software, to simulate the wave propagation and the interaction of ultrasound with the introduced flaws in the axle. For the axle inspection, it is shown that although the 5 MHz probe has shown a good versatility when inspecting from the surface, the 7.5 MHz probe delivers a better performance when inspecting from positions further away from the flaws. This is because the 7.5MHz probe has a higher focal range, which makes it more adequate to cover further regions. Furthermore, the ultrasonic simulation results have shown a good agreement with the experimental results obtained during this study. Source


Liaptsis D.,Twi Ltd. | Cooper I.,Twi Ltd. | Jian J.,Twi Ltd. | Boyle K.,Twi Ltd. | And 5 more authors.
Non-Destructive Testing Conference 2010, NDT 2010 | Year: 2010

As part of the development of a new manual Non Destructive Testing (NDT) system combining complementary inspection techniques, an inspection system based on Phased Array Ultrasonic Testing (PAUT) for detection of transverse cracking in solid railway axles is being developed. This paper presents the initial study, which includes the PAUT experimental setup and the initial results obtained after testing the system on railway axle test blocks. In this study the inspection of solid axles from their axle end face is investigated. The goal to performing the inspections from the axle end face is the advantage that the wheelset can be inspected whilst still on the train and therefore with minimal wheelset disassembly. Different end face inspection scanning configurations are presented including pulse echo and pitch-catch techniques. The experimental results are compared to assess the probe's detection capabilities and to determine the sensitivity that can be achieved. Experimental results show that spark eroded notches of depth 1mm, 3mm and 5mm introduced on the wheel seat and on adjacent curved areas of the axle test blocks were all detectable from the axle end face. In addition to practical experimentation, a series of modelling studies were undertaken using CIVA ultrasonic modelling software, to simulate the wave propagation and the interaction of ultrasound with the introduced flaws in the axle blocks. © (2010) by the British Institute of Non-Destructive Testing All rights reserved. Source

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