Donald R. Thornburg

Magnetic properties of (110) [001] oriented low alloy iron

Magnetic characteristics have been determined for several 6 mil thick samples of low alloy iron with strong (110)[001] orientations. These textures have been obtained by primary recrystallization and normal grain growth in iron base alloys with small additions of Si, Cr, and Mn. This presentation will discuss how highly oriented specimens were obtained by the control of chemical composition, processing, and final annealing. Both the texture and magnetic properties of these alloys will be described. The strong (110)[001] textures were confirmed by torque measurements, magnetic properties, reflective X‐ray pole figures, and quantitative domain analyses.

The effect of coatings on the stress dependent magnetic properties of oriented silicon steel

The effect of laboratory applied mill-glass and high stress secondary coatings on the magnetic properties of oriented 3% Si Fe was determined by examining the dependence of the core losses and exciting characteristics on uniaxial stress. The results indicate that bare specimens required the least compressive stress to cause an increase in losses. Mill-glass and secondary coated specimens could withstand larger compressive stress before the losses are degraded. For quantitative analysis, a loss-degradation stress parameter (σ.1) was defined. Typical values of (σ.1) for bare, mill-glass, and secondary coated specimens were 0.66, 2.58 and up to 4.94 MPa respectively. It is shown that the (σ.1) values increase linearly with applied secondary coating weight. The (σ.1) values are apparently related to the residual or coating induced stress in the specimen. It was noted that the minimum in the exciting characteristics occurred at a compressive stress close to the (σ.1) value.

The effect of force fitting on the magnetic properties of iron-cobalt alloy ring samples

Ring samples of annealed iron-27% cobalt (Fe-27 Co) and iron-cobalt-2% vanadium (FeCo-2V) alloys were subjected to a number of force fitted conditions where the maximum tensile and compressive hoop stresses were varied from 0 to 50 MPa. Various dc and 400 Hz ac magnetic characteristics were determined at each stress level. The dc and 400 Hz ac characteristics of both alloys changed in the force fitted condition, with the compressive hoop stress having more of an effect than the tensile hoop stress on most of the magnetic properties. The most drastic changes were observed in the 400 Hz exciting characteristics at 2.0 T in the FeCo-2V alloy, where the unstressed value of 111 VA/kg was increased to 1700 VA/kg at a calculated maximum compressive hoop stress of -49 MPa. The Fe-27 Co alloy, although having poorer exciting characteristics at the same induction level, changed from 880 VA/kg to 1500 VA/kg at -50 MPa, the conclusion being that the Fe-27 Co alloy is less stress sensitive than the magnetically superior FeCo-2V.

Effect of annealing on the magnetic characteristics of iron-27% cobalt alloys

This paper describes the changes in magnetic properties of iron-27% cobalt alloys undergoing various annealing treatments. Two commercial heats (0.2 and 0.1 mm thick respectively) of similar compositions were studied. The anneals were carried out in both dry hydrogen and vacuum for a variety of temperatures up to 1200°C. After annealing, the magnetic properties were measured, the samples were examined metallographically, and the residual carbon and sulfur contents were determined. Results indicated that annealing in a dry hydrogen atmosphere was superior to heat treating under vacuum. The best annealing temperature to obtain good overall magnetic properties was 900°C. A slightly higher annealing temperature, 925°C, caused severe degradation in magnetic properties. It is suggested that the poorer properties are related to the presence of the alpha/gamma phase transformation at 925°C. Annealing at temperatures above 925°C caused improvement in some of the magnetic properties. Coercive force (H c ) seemed most sensitive to annealing conditions, with a strong positive correlation being found between H c and the carbon plus sulfur contents after annealing.

The effect of manganese and sulfur on the development of orientation (110) [001]‐oriented low‐alloy iron

An investigation was made to determine the role of manganese and sulfur concentration on the development of (110) [001] orientation in low‐alloy iron specimens by primary recrystallization and normal grain growth. Fifteen heats, containing nominally 0.8% Si and 0.6% Cr with varying Mn and S contents, were used for the study, with three‐stage processing to 0.15 mm thick strip. The manganese content was varied between 0 and 0.15% with nominal sulfur contents of 0.001, 0.006, and 0.012%. Torque and magnetic properties, as well as X‐ray pole figures, were used to evaluate the orientation after final annealing. The low‐sulfur alloys (0.001% S) did not develop the best (110) [001] orientations. Those specimens containing the higher sulfur concentrations (0.012% were poorly oriented, except for one specimen which contained essentially zero Mn (<0.01%). All the specimens with nominal 0.006% S content developed strong (110) [001] textures with B10 values of up to 1.93 T and 60 Hz core losses at 1.7T as low as 1.5 ...

Optimized compositions for (110)[001]-oriented low-alloy iron

A statistically-designed experiment was performed to identify optimum compositions for high permeability and low core loss in