JASM: DISSIMILAR WELDING OF NEW HIGH OXIDATION MATERIAL – THOR™ 115 WITH GRADE T/P92

The constant development of steels and alloys used in the power generation industry for the production of boilers characterized by high steam parameters presents new challenges. Implementation of new combinations of alloying agents aimed at obtaining the best possible mechanical properties, including creep resistance, greatly affects the weldability of new steels. Every new steel or alloy grade has to undergo many tests, particularly in regards to bending and welding, in order to enable the development of manufacturing technologies, ensuring failure-free production and assembly of complete boiler systems. 9% Cr martensitic steels, used in the manufacturing of steam superheaters, are characterized by good creep resistance and, at the same time, low oxidation resistance at a temperature in excess of 600°C. In turn, steels with a 12% Cr content i.e. THOR™ 115 are characterized by significantly higher oxidation resistance in very high temperatures.

The combination of both steel grades working in perfect harmony could be found in boiler systems where superheater headers are fabricated out of grade 92 while superheater coils are produced from Thor™115 (Tenaris High Oxidation Resistance) material. This paper is focused on extensive research on the weldability of both grades welded with different filler metals.