Cracking Of Carbon Steel Components Due To Repeated Thermal Shock

Repeated thermal shock loading is common in the operation of pressure equipment particularly in thermal power stations. Thermal shock can produce a very high stress level near the exposed surface that eventually may lead to crack nucleation and crack growth. This paper presents a unique experimental study and outlines the information being gained from this work. In the experiments, cracks are initiated and then grown in low carbon steel specimens exposed to repeated thermal shock. The test-rigs achieve large thermal shocks through the repeated water quenching of heated flat plate specimens. The effect of steady state loads on the growth and environmental effects due to the aqueous nature of the testing environment are found to be major contributors to the crack growth kinetics. The most important findings are that the conditions leading to the arrest of cracks can be identified and that the depth of a starter notch contributes little to the crack propagation

Sancassania chelone Oudemans, 1916 (Acari: Acaridae) associated with pest beetles: New records and new hosts in Hungary

The hypopi of the species Sancassania chelone Oudemans, 1916 were collected from four pest beetle species, namely Melolontha melolontha (Linnaeus, 1758); Melolontha hippocastani Fabricius, 1801; Holochelus aequinoctialis (Herbst, 1790) and Tropinota hirta Poda, 1761. The infestation rate was the highest in H. aequinoctialis (80%), while it was 50%, 28% and 13% in M. hippocastani, M. melolontha and T. hirta, respectively. The majority of the mites were found on wings in case of the two Melolontha species, in contrary, the mites were present on the abdomen of the H. aequinoctialis and T. hirta. Melolontha hippocastani Fabricius, 1801; Holochelus aequinoctialis (Herbst, 1790) and Tropinota hirta (Poda, 1761) are new host species of S. chelone