Abstract The crystallographic aspects after air-quenching treatment and the pitting corrosion resistance after single tempering and double tempering treatments of AISI 420 martensitic stainless steel were studied using optical microscopy, Electron Backscatter Diffraction and potentiodynamic polarization tests. The results showed that the observed average orientation relationship (OR) was closer to the Greninger-Troiano (G-T) OR model with a minimum average deviation of 2.66°. The average OR of AISI 420 steel with respect to austenite matrix was φ1 = 3.6°, Φ = 46.0°, φ2 = 6.2° in the area mapped. Blocks showed variant pairs belonging to the same Bain group forming sub-blocks with misorientation 5.51° < 6 ¯ 0 11> (V1/V4 pair), consequently, the AISI 420 martensitic stainless steel showed higher intervariant boundary density for the same Bain group and close-packed plane group. In the same air-quenching condition, the different sizes of prior austenite grain in the microstructure did not influence the variant selection. The air-quenching and single tempering treatments did not impair the pitting corrosion resistance and did not cause significant loss of hardness in relation to the air-quenched treatment. Therefore, the double tempering should be dispensed saving production costs.

The influence of hot-band grain size and additions of aluminum and manganese on the magnetic properties of non-oriented grain (NOG) low-carbon electrical steel with about 3 wt. (%) Si were investigated using optical microscopy and X ray diffraction. The addition of manganese resulted in larger grains after final annealing. Coarse grains in the hot-band and addition of Mn led to a Goss orientation component after final annealing, which resulted in an increase in the magnetic permeability.

The oxide layer formed on the surface of a grain oriented silicon steel was characterized by SEM and EDS. 3% Si steel substrates were coated by two types of slurries: one formed by MgO and water and other formed by MgO, water and SrSO4. The ceramic films were evaluated by SEM, EDS and X-ray diffraction. Depth profiles of Fe, Si and Mg were obtained by GDS. The magnetic core losses (at 1.7 Tesla, 60 Hz) of the coated steel samples were evaluated as well. The use of MgO containing strontium reduced the volume fraction of forsterite particles beneath the outermost ceramic layer. It was observed a reduced magnetic core loss with the use of the slurry with MgO containing strontium.