This paper attempted to estimate the values of the cavitation pressures of seal-type thrust bearings with dimples of different diameters and depths, comparing experimental and analytical results. In the experiments, the oil film forces were measured for the various dimpled bearings with a fixed oil film thickness. The measured oil film forces were simulated by CFD analysis and the mass-conserving cavitation algorithm which implemented the JFO theory, using various cavitation pressures. In addition, cavitation pressures for a dimple were measured experimentally in various rotational speeds. As the results, the estimated cavitation pressures from the JFO analysis were slightly larger than those from CFD analysis. Cavitation pressure did not change much for the different dimple diameters, while it increased as the dimple depth increased. The measured cavitation pressure was generally consistent with the estimated results by CFD analysis, and it tended to increase gradually with increasing rotational speed.

It has been reported that pitting corrosion occurs in stainless steel under the specific conditions which a corrosion factor superimposes. In cold and snowy area, welded structures on the outdoors are exposed to combinational environment of the salt damage and the freezing damage, in which the corrosive solution containing Cl― chlorine ions from the sea breeze and snow melting agents undergo freezing-thawing cycles during the winter. The cause of pitting corrosion phenomenon which occurs in the welded stainless steel under such an environment has not yet been clarified. In the previous report, accelerated pitting corrosion is confirmed to have occurred as a result of concentration cell corrosion due to a local concentration of Cl― chlorine ion around a weld bead during freezing and thawing of the solution. In the present study, it is investigated that the effects of different corrosion environment and different welding condition on the residual strength of weld part of the stainless steel. Austenitic stainless steel SUS 304 plates with bead-on-plate welding are used as specimens. The specimens are fully immersed in FeCl₃ solution. The freezing-thawing environment is created by temperature cycling form 20°C to -20°C. One cycle of freezing-thawing is 12 hours. As a result, large-scale pitting corrosion under freezing and thawing environment was induced mostly in the area of a high tensile residual stress and was larger than under the constant temperature environment. It is confirmed that the residual strength of the weld specimen using CO₂ gas are weaker than specimen using argon gas.