Effect of thermal and mechanical treatments on corrosion of API X-52 grade line pipe steel in flowing 3.5% NaCl solution

611-614Commercial API X-52 grade line pipe steel was studied for its corrosion resistance in 3.5% NaCl solution under static and dynamic conditions. Heat treatments and cold rolling resulted in considerable variations in mechanical properties and microstructure of the steel. These treatments resulted in insignificant changes in static corrosion rate, whereas considerable variations in corrosion rate were observed under dynamic conditions. Quenched and tempered steel showed the maximum corrosion resistance and annealed steel showed the minimum resistance under dynamic conditions

Microbiologically influenced corrosion of mild steel of cultures of sulphate reducing bacteria

327-329<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Microbiologically influenced corrosion (MIC) of mild steel samples were studied in two different bacterial strains, Pseudomonas fiuorescens and Desulphovibrio vulgaris, isolated from cutting oil emulsions by potentiostatic polarization technique. The relationship between the corrosion behaviour and presence of biofilm on mild steel samples were determined. Bacteria were mixed with corrosion products hindering the formation of a protective layer. In both media, anodic depolarization was observed in the presence of ferric iron reducing bacteria. Anodic depolarization was achieved by the bacterial reduction of ferric to ferrous compounds. In the absence of the bacteria, both anode and cathode were polarized.</span

Low-cycle fatigue behaviour of a low-alloy high-strength steel

The low-cycle fatigue behaviour of a high-strength CrMoV steel has been evaluated in the as-received (AR) and the quenched and tempered (QT) conditions, at room temperature. While the quenching and tempering treatment causes a marked increase in the tensile strength and hardness, it leads to an impairment of the fracture toughness and the low-cycle fatigue (LCF) resistance of the material. A fractographic examination reveals that while there is a large zone of fatigue crack propagation the AR condition, in sharp contrast there is small zone of fatigue crack propagation and a large zone of static fracture in the QT condition. The reduction in fatigue resistance of the QT material is attributed to a loss in fracture toughness and a fall in the values of ε'<SUB>f</SUB> and n'