Effect of temperature on the interaction of ÉP823 steel with lead melts saturated with oxygen

We study the corrosion behavior of ferritic-martensitic éP823 steel in a static lead melt, saturated with oxygen, at 550 and 650°C. At these temperatures, a complex magnetite-base scale is formed on the surface of steel, but the mechanisms of its growth are different. At 550°C, corrosion has a cyclic character. On the surface of steel, a Fe_1+x Pb_2−x O₄−Fe_1+x Cr_2−x O₄ two-layer scale is formed periodically. Reaching the critical thickness (18 μm), it exfoliates along the interface with the matrix, to which oxygen-containing lead penetrates, whereupon this process is repeated. The corrosion rate is ∼0.08 mm/year. At 650°C, the intensification of reactions of formation of chromium spinel and plumboferrite induces the growth of a porous scale, where lead is accumulated. This scale has good adherence to the matrix and is formed as a compact conglomerate owing to the efficient mass transfer at all interfaces, which leads to a catastrophic rate of thinning of the specimen (3.82 mm/yr) in a lead melt. On the basis of experimental data, we propose schemes of the oxidation of chromium steels in a lead melt with a high oxygen activity at different temperatures. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 2, pp. 77–84, March–April, 2007.     

Effects of rolling texture on fatigue failure in 07Kh13N4AG20 steel

Notched circular cylindrical specimens have been cut in the plane of the sheet from 07Kh13N4AG20 steel along and transverse to the rolling fibers and have been tested in bending with rotation, with the determination of the fatigue ridge step (fatigue crack microgrowth rate) together with the stress intensity coefficients K. It is concluded that there is a substantial effect from the rolling texture in the plane of the sheet on the kinetics of the fatigue failure.Translated from Problemy Prochnosti, No. 12, pp. 26–31, December, 1992.     

Corrosion of 12Kh18AG18Sh steel in contact with copper

The anodic dissolution rate of 12Kh18AG18Sh steel increases due to its contact with copper at temperatures of 65–100°C. The difference-effect coefficient is 0.375 at 75°C. A copper cathode is almost twice as efficient as a steel one, and an increase in its area results in a sharp increase in the corrosion current density of steel. We established experimentally that, in the temperature range 85–100°C, the formation of a galvanic element with copper leads to pitting corrosion of 12Kh18AG18Sh steel owing to polarization to a more positive potential than the pitting-formation one. But, at temperatures below 65°C, a protective effect caused by polarization to a more negative potential than the steady-state potential is observed. In this case, the current of anodic dissolution of copper grows insignificantly. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 35, No. 64, pp. 101–104, November–December, 1999.     

Corrosion of armco iron and model Fe−Cr-Al alloys in oxygen-containing lead melts

We studied the influence of oxygen-containing (6·10⁻³ wt.% O) lead on the corrosion of Armco iron and Fe−16Cr, Fe−16Cr−1Al alloys at a temperature of 650°C under stationary conditions. The front of corrosion propagates according to a linear law and this process is periodically repeated. In each period, an oxide film based on Fe₃O₄ magnetite is formed on the surface of the metal and lead penetrates into the suboxide zone. This leads to the exfoliation the external oxide film and then the process is repeated. Under the indicated testing conditions, alloying with chromium and aluminum intensifies the process of corrosion in iron. Karpenko Physicomechanical Institute, Ukrainian Academy of Sciences, L'viv. Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 33, No. 2, pp. 84–88, March–April, 1997.