Papers by Keyword: AISI 304 Steel

Abstract: It is commonly believed that stainless steel cannot rust. However, this erroneous assumption is very often disproved in practice. Either the stainless steel is chosen for the manufacture of a piece of equipment working in the conditions where its corrosion resistance is no longer satisfactory, or, more often, the prescribed procedures for its protection are not followed during operation. The article gives examples where an incorrectly chosen disinfecting procedure for a food processing plant with a chlorine-based product caused pitting corrosion of ceiling panels and low-quality weld joints caused crevice corrosion of cold drinking water pipes in food processing plants.

Abstract: A two-dimensional elastic-plastic finite element model was built to simulate the closure of a long fatigue crack with arbitrarily shaped crack faces. The model growth is simulated by the successive mesh splitting along the crack path defined by element edges. To obtain a realistic morphology of the fracture surface, fatigue crack growth experiments with CT specimen made from AISI 304 stainless steel were performed and fracture surface topology was determined using a single camera and a depth-from-focus method. Simulated closing loads and closure lengths for the cracks with rough and smooth faces and for plane-stress and plane-strain conditions are compared. A mismatch of rough crack faces, resulting in an additional contact, is visualized.

Abstract: Phosphoric acid treatment is used as a way to improve the high temperature oxidation resistance of a chromia-forming AISI 304 steel. Chromia-forming steels are excellent candidates to resist to high temperature oxidizing atmospheres because of the formation of protective oxide scales. The oxide scale growth mechanisms are studied by exposing phosphoric acid-treated and untreated 304 steel samples to high temperature conditions in air. The analyses were carried out by means of thermogravimetry, and in situ X-ray diffraction (XRD). The experimental results show that the phosphoric acid treatment does not have a beneficial effect on cyclic high temperature oxidation (up to 70h of the oxidation test) of AISI 304 steel because of growth of a layer mainly formed by external cation diffusion which grows very quickly. The isothermal high temperature oxidation of this steel at 800°C in air shows a very fast initial iron oxidation towards the external interface, allowing to chromium element to be more available to the internal interface to form a continuous chromia layer, thus causing the establishment of a parabolic oxidation regime and leading to a beneficial reduction of the oxidation rate (after 70h of the oxidation test).

Abstract: The paper briefly examines the metallurgical effects of shock waves on different metals. Two points are then specifically addressed. The first one regards how X-ray diffraction (XRD) can be usefully employed to get exhaustive information about the microstructure of a shock loaded metal. The second point concerns the mechanisms of martensitic transformation in alloys such as AISI 304 when submitted to repeated explosive deformations.