Microstructural investigation on the failure in APMT/KHR45A dissimilar weld interface after long-term service at high temperature

NbC TRANSFORMATION DURING AGING IN HP40-Nb HEAT RESISTANT ALLOY

“…They contain in their heat exchange surfaces, which are necessary for the process, an arrangement of metal tubes that are generally vertical and make up, together with other parts, the surfaces where the reforming reactions take place. The reformer furnace tubes are the most critical components, as they are exposed to severe conditions in terms of high temperature and internal pressure for long time during service, and have inner diameter of 60-200 mm, wall thickness in the range 10-25 mm and length of 10-15 m and with a designed nominal life of up to 100,000 h [1][2][3][4][5]. Since service conditions involve high temperatures and moderate pressures, the materials used for reformer tube demand for higher creep and oxidation resistance.…”

“…Since service conditions involve high temperatures and moderate pressures, the materials used for reformer tube demand for higher creep and oxidation resistance. Therefore, the centrifugal cast HP40-Nb alloy, namely 25Cr35Ni1Nb, has been developed by adding a small amount of Niobium into HP40 alloy [5][6][7][8][9][10]. This austenitic alloy contains in its composition large concentrations of chromium (up to 35%) and nickel (up to 45%), which improves a high resistance to oxidation and carburization [11][12][13].…”