The surface of steel S235 was oxidized by Cl2 gas and checked for its electrocatalytic efficiency regarding oxygen formation in aqueous solution. If exposed to humid Cl2 gas for 110 min, steel S235 became an electrocatalyst that exhibits an overpotential for the oxygen evolution reaction (OER) of 462 mV at 1 mA cm(-2) at pH 7. The OER activity of the same sample at pH 13 was moderate (347 mV overpotential at 2.0 mA cm(-2) current density) in comparison with OER electrocatalysts developed recently. Potential versus time plots measured at a constant current demonstrate the sufficient stability of all samples under catalysis conditions at pH 7 and 13 for tens of hours. High-resolution X-ray photoelectron spectra could be reasonably resolved with the proviso that Fe2 O3 , FeO(OH), MnO(OH), and Mn2 O3 are the predominant Fe and Mn species on the surface of the oxidized steel S235.

YAG laser riveting of Ti-6Al-4V/CFRP lap joint was successfully realized-Tensile strength is comparable to that of conventional riveted lap joints-Fatigue strength of conventional riveted joint can be increased by adhesive bonding-The effect of adhesive bonding is comparable to surface structuring of Ti-6Al-4V

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The efect of postweld heat treatment PWHT) on 2.6-mm-thick Ti-6Al-4V but joints that were welded using a continuous-wave 8-kW yterbium ibre laser was studied in terms of the microstructure, microtexture, number of welding defects, microhardness, residual stress distribution and high cycle fatigue HCF) properties. Five types of heat treatments in the temperature range of 540-920°C are investigated. The main reasons leading to fatigue life deterioration after the laser welding process are discussed, and possible guidelines for further improvement of the HCF behaviour by a subsequent suitable type of PWHT are provided. Low-temperature annealing T < 600°C) tends to harden both the base material and the welding zone without any signiicant efect on the fatigue properties. Heat treatments at higher temperatures T > 50°C) lead to the transformation of a strong martensitic structure in the fusion zone FZ) into more ductile coarse lamellar, which is more beneicial for fatigue performance. A suitable type of PWHT can increase the fatigue limit of a laser-welded Ti-6Al-4V but joint by 10%; however, a slight decrease in static strength should be considered. The efect of stress relief at elevated temperatures is studied.