NUMERICAL CHARACTERIZATION MODEL OF VECTOR HYSTERESIS FOR MAGNETIC MATERIALS
The paper presents a numerical method based on Preisach model for the characterization and modelling of hysteretic magnetic materials exhibiting vector hysteresis, with acceptable accuracy, based on minimal material measurement data. The identification approach based on the Everett distribution function is a way to obtain accurate numerical solutions when the experimental data of the magnetic material are scarce, for instance: there are known only the initial magnetization curve and the upward major branch for two directions (rolling and transverse ones). The comparison between the measured and simulated major loop curves for another magnetization direction shows good agreements.
A Preisach-Stoner-Wohlfarth Vector Model
In previous papers we presented a new model of vector hysteresis, called RVM. The crux of the model is the definition of a vector hysteron, described in the H-space, and limited by a closed critical surface. Generally, the critical surface may be any closed simply connected surface, such that each surface point has a unique surface normal. The magnetization computed should be a conservative function of the applied field, and constant in magnitude. This paper proposes a new model, called the PSW vector model, for the magnetization outside the critical surface. It is a generalization of the RVM based upon the merging of the vector Preisach model and the Stoner-Wohlfarth model.
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.