Influence of steel characteristics on the corrosion resistance of tubing under carbon dioxide corrosion conditions

Results of bench corrosion tests of tube steels in real well mediums of oil fields of Production Association “Belorusneft” are presented. Corrosion resistance of plain carbon steels 32Mr1A N80 (Q) API Spec 5CT, 37Mr2V E GOST 633, low-allowed steels 30Cr L80(1) API Spec 5CT, 32CrMr P110 API Spec 5CT, 25CrMrB K72 GOST 31446, 30CrMrMoA-1 C90 API Spec 5CT has been evaluated. It was found that hot-rolled plain carbon steel with coarse-grained microstructure is subject to more intense local corrosion than similar steel with a fine-grained microstructure after quenching and high tempering. Analysis of the composi-tion and microstructure data of the investigated materials indicates that, under given conditions, the main factors reducing the corrosion resistance of the investigated materials are the manganese content of more than 1 % wt., the heterogranularity and the presence of metallographic structure of Widmannstetter. It is established that tube steel with chromium content of 0.5 % wt., micro-alloyed with calcium and boron, having fine-grained structure with 12 grain grades according to GOST 5639, can show increased corrosion resistance on a par with tube steel with chromium content of 1 % wt., having fine-grained structure with 10 grain grade according to GOST 5639. The obtained results can be used when selecting materials for operating under the conditions of oil fields in the Republic of Belarus