Optimization of image synthesis for complex geometry objects in the robotic ultrasonic system
This paper is devoted to the optimization of image synthesis for complex shape objects in the robotic system of ultrasonic testing. The basis of this process is a preliminary analysis of the object with complex geometry to ensure reproducibility and accuracy of the tests in the specified range. It includes such stages as digital model creation, geometric surface analysis, creating of control points and vectors, searching for optimal model location, model verification on reachability, collisions and singularity.
Ultrasonic Sampling Phased Array Testing as a Replacement for X-ray Testing of Weld Joints in Ship Construction
According to European Standard EN 1712 ultrasonic testing of thin-walled welded joints is mandatory for wall thicknesses of more than 8 mm only. Any thinner components do have to undergo X-ray inspection. Besides various advantages of X-ray testing viz. high sensitivity to smallest inclusions, high acceptance in the ship building sector and 'automatic' documentation of inspection results, there are also several deficiencies (like radiation protection issues, inspection time expenditure etc.) creating a reasonable request for more cost-effective alternatives. Sampling Phased Array technology introduced by Fraunhofer-IZFP provides significant improvement of flaw detectability also in thin-walled welded joints due to its tomographic approach in processing of signals obtained by ultrasonic phased array transducers. It allows high-quality imaging of welded joints and detection of relevant material flaws. Real-time ultrasonic imaging with tomographic quality offers a great alternative to X-ray testing with respect to inspection speed and modern documentation of inspection results. The basic principles of Sampling Phased Array are presented in the paper and several application results obtained on welded joints of marine objects are presented.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.