| ABSTRACT: |
A CORRELATION STUDY BETWEEN INTERGRANULAR STRAINS AND MAGNETIC
PROPERTIES OF MILD STEEL
R. Hutanu1, L. Clapham1, and R. Rogge2
1Department of Physics, Queen’s University, Kingston, Ontario, Canada; 2National Research Council,
Steacie Institute for Molecular Sciences, Neutron Program for Materials Research, Chalk River, Ontario,
Canada.
Residual stresses arise during manufacturing processes and installation of engineering components, and they
add to the active stresses in service. Recently residual stresses have been categorized as being of different
types: Type 1 or macroscopic stresses and type 2 or intergranular residual stresses (IS). Macroscopic
residual stresses exist on the length scale of the deformed specimen, while IS are microscopic (grain size
scale) and appear due to the inhomogeneous deformation of grains oriented in different crystallographic
directions. Neutron diffraction data has shown that in steel alloys, the [100] direction carries the largest
amount of IS. Interestingly, the same direction is the magnetic easy axis direction in steels. Our study
focuses on the correlation between the IS and the magnetic properties of mild steel. A number of mild steel
samples were plastically deformed at different strain levels then unloaded. Samples deformed to low strains
exhibited Luders bands on the surface, while those deformed to higher strains were homogeneous. The
Magnetic Barkhausen Noise (MBN) technique was used to characterize the magnetic behavior, while
neutron diffraction was employed in order to study and measure directly the IS in different crystallographic
directions. A direct correlation was found between the IS in the [100] direction and the bulk magnetic easy
axis direction as determined by MBN.
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