Influence of Dry Friction on the Wear Behavior of X52 Steel -Experimental Study and Simulation Using Response Surfaces Method

The objective of this work is to identify the most influential parameters on the friction coefficient and wear rate, using the response surface method. The friction tests were carried out by adopting the methodology of complete planes 23at three factors ("D", "V" et "Py"), at two level for each factor. The results show a decrease in the wear rate when the three factors are at their highest level and a decrease in the friction coefficient when using minimum loads and speeds on important distances. In addition, the developed mathematical models make it possible to reveal a correlation between the test parameters and the responses studied in their studied domain. An evaluation of the volume parameters "Vmc" and "Vvv" was carried out. The morphology of the worn surface shows that the friction under a load of 1 N leads to the predominance of an abrasive wear mechanism, while a load of 10 N favors an adhesive wear mechanism, increasing the parameters "Vmc" and "Vvv" to the maximum.

Performance Assessment of Magnesium Anodes Manufactured by Sintering Process

This work shows the performance of cathodic protection systems formed by an API (American Petroleum Institute) X52 steel exposed to seawater and coupled with galvanic anodes of Mg, Mg-1Cr, and Mg-1Nb fabricate by sintering technique at a temperature of 500 °C. Potential monitoring indicates that X52 steel of the three systems remained in the protection zone. Mg-Nb/X52 system showed the more stable potentials since the first day; the recorded values remained between –1.0 and –1.1 V vs SCE (saturated calomel electrode) during the seven days of exposure time. Current density records show that Mg/X52 system had the most stable values, while the other two systems (Mg-Cr/X52 Mg-Nb/X52,) had current fluctuations. The Mg-X52 system recorded the most negative potential values, which can be attributed to a greater magnitude and a better distribution of the cathodic protection current. However, the Mg-Nb/X52 system had a better result because the current drained by the system was constant throughout the experiment.

Effect of the Physicochemical Properties of Soils on Generalized and Localized Corrosion Rate of API X52 and X60 Pipeline Steels

This work analyzed physicochemical properties of different types of soils on the generalized and localized corrosion rate in two steels (X52 and X60) most used in pipeline transportation of hydrocarbons. The physicochemical properties such moisture content, pH, resistivity and redox potential, which influence the corrosion rate of the pipelines were analyzed. Soils from three different sites in the south of México were obtained. Soils were sampled approximately 1.5 m deep, close to pipeline. From the analysis of generalized corrosion results taking into account the type of soil, it was observed that the most corrosive soil for the two steels was soil-3, generating corrosion rates of 0.119 and 0.097 mm/year, for the X52 and X60 steels respectively, after a period of 6 months. It is important to note that the maximum generalized corrosion rate was obtained after 1 month of exposure of the steels, generating corrosion rates of 0.177 and 0.162 mm/year, for the X52 and X60 steels respectively. In similar way, the localized corrosion rates for the both steels were higher when steels are exposed to Soil-3, generating corrosion rates of 1.1 and 0.45 mm/year, for X52 and X60 steel respectively, after a period of 6 months. In general it was observed that X60 steel presents greater resistance to pitting corrosion rate (in Soil-3), which can be attributed to its more homogeneous microstructure, fine grain size, and its chemical composition that presents elements such as Cr and Ni in greater quantity than X52 steel, which improve the corrosion resistance. However, depending on the type of soil the corrosion resistance behavior of each steel is different. From the analysis of various equations fits, it was determined that the potential equation is the one that gives the best fit for all cases.