pipe flow; determined indirectly by Well inger and Vetz for particles suspended in air.Assuming a value of 10° for a and K 1 m/s, the value of V at which erosion would commence is 5.8 m/s. At 20° and 30°, erosion would commence at 3 m/s and 2 m/s, respectively. Given these values, it is reasonable to suggest that a small amount of surface roughening produced by corrosion would substantially increase the angle of impact and increase the rate of metal loss by erosion. Conversely, the elimination or reduction of the corrosion component could greatly reduce the erosion losses. These suggestions are borne out by the results of the present study. Conclusions1. Surface roughening due to corrosion increases the local angle of impact of use slurry particles and hence greatly increases the erosion rate; in slurry pipelines carrying sand slurries. Hence, an inhibitor-induced reduction in the corrosion rate also reduces the erosion due to the resulting smoother surfaces.2. The bulk of the metal loss in the absence of inhibitors is due to the straight mechanical erosion of the corrosion roughened surfaces. AbstractSulfide corrosion cracking of linepipe steel was studied from metallurgical and environmental standpoints using laboratory and full size tests. Sulfide corrosion cracking can be classified into hydrogen induced cracking (HIC) and sulfide stress cracking (SSC). HIC initiates at an elongated inclusion and tends to propagate along microstructural inhomogeneity. The addition of copper was effective in preventing HIC in a relatively mild BP solution, due to the formation of a protective film, but was ineffective in a NACE solution. Calcium treatment of desulfurized steel was effective in preventing HIC initiation. Optimization of the manganese content for controlled rolled plate, and the quenching and tempering process were effective in controlling HIC propagation in a NACE solution.SSC in linepipe steel was closely related with HIC. Measures for HIC were also effective in increasing SSC resistance. Girth welded joints were the most susceptible since SSC occurred at the hardest point in the heat affected zone of the final welding pass. Critical hardness for SSC under the stress level of 1.3 times the yield deflection was Hy 250 and 280 for 1.0 and 0.1 atm partial pressure of H 2 S gas, respectively. In a full size HIC test simulating an actual pipeline, HIC developed only in the inner side of the steel, resulting in a decrease of the average crack length by one half as compared with laboratory test results. The residual tensile stress of 50 kg/mm 2 due to girth welding did not introduce any SSC by itself. addition of copper (Cu) prevents HIC because of the formation of protective film." The chemical compositions of the recent steel Abstract Corrosion behavior of for steel has been studied in both stagnant and deaerated solutions containing NaCI concentrations of 200, 1000, and 5000 ppm and sodium nitrite concentrations of 10 -3 N, 10 -1 N, and 1N, respectively. The samples did not show corrosion in the presence of 10 -1 ...
This pa/Jer describes a part of results of continued developmental activity to obtain optimum chemical composition and processing conditions in the production of high strmgth steel with high toughness by controlled rolling .I t was noted in laboratory experiment and mill test that niobium most e.ffectively improved the frac ture ap/Jearance transition temperature (v T s) when a strong controlled rolling was applied, while vanadium was less effective in this res/Ject. Steels containing both of niobium and vanadium also /Jossessed a v T s similar to th at of Nb-bearing steels . Addition of a small amount of nickel, chromium, and cop/Jer to Nbor V -bearing steels enhanced precipitation hardening presumably by lowering the r-+a transformation temperature withou t deteriorating the v T s. The improvement of v T , by controlled rolling was consistently described by the total rolling reduction given at below 900"C, and was less de/Jendent on rolling reduction of individual pass .L owering carbon content to below a level of 0 .07 0 0 in the Nb-bearing steel considerably improved impact shelf energy without arry loss in LYS. T ransverse shelf energy was also improved by decreasing sulfur content and application of cross rolling . H owever, an intensive controlled rolling slightly decreased shelf energy.A combination of the above knowledge has made the production q! tough high strength steels possible, and a few such examples qf line/Ji/Jf plate are shown.
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