Magnetostriction of duplex stainless steels

Abstract

To identify suitable non-destructive examination techniques, the saturation magnetostriction of a number of ferritic–austenitic (duplex) stainless steel samples from various manufacturers has been measured using a dilatometric technique. The values were found to lie in two distinct ranges, which suggested that two types of material structure were present, often in the same steel type. By examination of optical micrographs of all the samples, it was confirmed that the two ranges of saturation magnetostriction corresponded to two types of structure as follows: (15·5 ±3·3) ×10⁻⁶ (average) in the rolling direction for highly anisotropic material structure and (5·7 ± 2·2) × 10⁻⁶ (average) for isotropic material independent of orientation and for highly anisotropic material perpendicular to the rolling direction.

MST/945