Abstract
There are strong environmental and economic pressures to increase the thermal efficiency of fossil fuel fired power stations, and this has led to a steady increase in steam temperatures and pressures resulting in worldwide plans for ultrasupercritical power plants. Basic investigations on the weldability of advanced 9–12%Cr steels which are either currently in use or which are intended to fulfil this requirement were performed on pipes of P91, E911 and a tungsten containing cast steel G-X 12 CrMoWVNbN 10 1 1. Gleeble simulations representing the manual metal arc welding process were applied to produce HAZ simulated microstructures. After different post-weld heat treatments they were tested using hardness tests, metallographic investigations, constant strain rate tests, and creep tests. Particular attention was given to the softening effect in the HAZ and its influence on the creep resistance of the welded material. This decrease, shown by simulated and manufacturing welded samples, seems to be less pronounced for the tungsten modified versions than observed with the P91 material.
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