超（超）临界机组用P91钢老化性能研究

Investigation on Aging Properties of P91 Steelin Ultra-supercritical Power Units

基于在70MPa和650℃下9000h的老化试验，研究了P91钢的显微结构和短时力学性能变化特点。结果表明：在温度和应力的双重作用下，老化后期板条马氏体明显碎化，亚晶数量增加，且向等轴转变；主要析出相M23C6在1000h后尺寸和数量明显增加，3000h后变化特征不明显；同时，老化初期宏观硬度、室温强度和高温强度均出现快速下降，而在3000h后组织趋于稳定。

In order to deal with early failure of the welding joints of water wall of the USC boiler, construction technology and application effect of the stress relief groove on the water wall were studied and developed. After researching, the stress relief groove of the fin near the joints for release and adjustment of local the regional effect of stress distribution of the effect is obvious; in a length, measuring point left the groove closer, stress changes more, with the increase of the distance, the stress values changed become smaller; with the length of the groove gradually lengthened, each measuring point stress value is gradually increased, when the slotting length reaches a certain length （50cm）, the stress value of each point of the measurement is no more increased and tends to be stable, the influence range of the groove is interrelated with its relative position and length and so on; synthesis of each measuring point stress change trend and the values of the measuring points, the slot spacing should be better in the 10 -15 water wall tubes when the length of the groove is about 50 cm.