Model-based investigation of the role of grain morphology in Ultrasonic and Magnetic NDE of the microstructure of steels

volker, arno; TNO; Netherlands

Volker, A.; TNO; Netherlands
Zhou, L.; University of Warwick; United Kingdom
Davis, C.; University of Warwick; United Kingdom
Kok, P.J.J.; Tata Steel; Netherlands

ID: ECNDT-0301-2018
Download: PDF
Session: Modeling and data processing Electromagnetic Techniques 1
Room: J2
Date: 2018-06-12
Time: 10:00 - 10:20

Rolling of strip steel causes texture, dislocations and grain elongation. To monitor the product uniformity during production these parameters should ideally be measured independently, either magnetically or ultrasonically. The objective of this study is to evaluate the measurability of grain elongation only, using numerical modelling of both methods. The crystallographic orientation is kept random such that the modelled microstructure does not contain any texture. Numerically modelled microstructures are used with varying aspect ratios from 0.2:1 to 5:1 in length. Each grain is described by its single crystal properties, and the three Euler angles define its rotation in space. The modelling of the magnetic flux density is performed using a 2D finite element model in COMSOL. The modelling of the elastic ultrasonic wave propagation is done using a 2D rotated staggered-grid finite-difference model. In both approaches each individual grain is included in the numerical model. Analysis of the modelling results shows that grain elongation has a minor influence. The model outputs indicate a 4% change in relative permeability and no significant difference was observed in the measured sound velocity and attenuation.