Hot corrosion of the weldment is the result of the reaction between oxidation and sulfidation, which affects welded joints exposed to combustion gases containing sulfate coal ash at high temperature. It is also demonstrated that welding processes, weld consumables, temperature of exposure, and mixture of salt environment are important factors in hot corrosion of the weldment.Hot corrosion is the main failure mode of welded components in the hot sections of gas turbines, boilers, metallurgical furnaces, and petrochemical installations. In this regard, the cyclic heating and cooling can mainly influence the corrosion behavior due to possible thermal stress on the weldment and their corrosion products. Hence, the maximum service temperatures of welded joints are decreased when exposed to hot corrosion environments.
<div class="section abstract"><div class="htmlview paragraph">The current work investigates the hot corrosion demeanour of Hastelloy X weldment produced with autogenous mode through key-hole plasma arc welding (K-PAW). The hot corrosion test has been performed for weldment in molten salt-1 (MS-1) (75 % Na<sub>2</sub>SO<sub>4</sub> + 25 % V<sub>2</sub>O<sub>5</sub>) and molten salt-2 (MS-2) (75 % Na<sub>2</sub>SO<sub>4</sub> + 20 % V<sub>2</sub>O<sub>5</sub> + 5 % NaCl) circumstance for 25 hrs (25 cycles) at 900 °C. The MS-1 substrate of both base metal and weldment provided the lowest weight gain than the MS-2 substrate. The NaCl in the MS-2 causes severe hot corrosion on the substrate, whereas the absence of NaCl in MS-1 reduces the hot corrosion effects. The highest parabolic constant is observed for K-PAW weldment in MS-2 condition. The tendency of hot corrosion rate follows the order of, Base Metal MS-1 < K-PAW MS-1 < Base Metal MS-2 < K-PAW MS-2. The occurrence of protective phases like chromium oxides (Cr<sub>2</sub>O<sub>3</sub>), spinel oxides (NiCr<sub>2</sub>O<sub>4</sub> and NiFe<sub>2</sub>O<sub>4</sub>) Nickel oxide (NiO) on the substrate resist the further oxidation. But, the development of MoO<sub>3</sub> and Fe<sub>2</sub>O<sub>3</sub> phases are increased the cracking as well as spallation rate which promotes severe corrosion of the substrates. The plasma arc welded substrate and base metal in MS-1 condition are giving better resistance than in MS-2 at 900 °C.</div></div>
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