Magnetic Studies of Residual Stress in Iron and Steel Induced by Uniaxial Deformation

Abstract

The nature of the residual stress in steel after uniaxial plastic deformation was investigated magnetically. The B-H curve measured in the residual stress state after elongation was similar to the one under compressive stress, and the induced magnetic anisotropy was uniaxial with the easy axis at right-angles to the previous direction of elongation. By employing a newly developed magnetic probe, which detects the sign and the magnitude of the induced uniaxial magnetic anisotropy under deformation, the magnetic yielding phenomenon was observed at the mechanical yield point. The probe output was highest at this point, compared with that observed during the subsequent cycles of loading. These results are interpreted semiquantitatively on the basis of the microscopic stress distribution and the anisotropy of the magnetostrictive strain.

Magnetic NDT technique to evaluate fatigue damage

“…Based on micromagnetics, dislocation theory, and probability theory, Seeger et al [5] have presented a theoretical treatment of the action of internal stresses on domain n alls and uniformly magnetized domains, and have established equations relating magnetic properties with mechanical properties. Abuku [6] has found that after uniaxial plastic defornia- &I. B. SHAH and M. S. C. BOSE tion of steel, the B-H curve in the residual stress state after elongation is similar to the one under compressive stress.…”

Magnetic Methods

“…For other methods refer to Section 9.11 for the magnetic anisotropy system "MAS" or "Sigmatron" [7], stress-induced magnetic anisotropy [8], directional-effective permeability [9], non-linear harmonic analysis [10] and magnetically-induced velocity change [11].…”

Magnetic behaviour of low-carbon steel in parallel and perpendicular directions to tensile deformation

“…5(a)) and BN envelope [6] exhibit a one peak shape, whereas in compression the two peaks are observed [6,7]. On the contrary after unloading from tension, permeability and BN shows two peaks after tension (Figs.…”

“…Despite of this, with recent improvement of measurement techniques the seemingly well-investigated topic stimulates lively debates about some interesting magnetic features of stressed ferromagnetic materials: two-peak form of differential permeability [3,4] and Barkhausen noise (BN) envelope [5,6] as well as corresponding bulging of hysteresis loops [4,7,8] with near onepoint crossing [2,5,8]. The problem is complicated by a wide variety of chemical and structural composition of investigated commercial steels.…”