超超临界机组锅炉用不锈钢管表面冷作硬化处理对其抗蒸汽氧化性能的影响

INFLUENCE OF COLD WORK HARDENING SURFACE OF AUSTENITIC STEEL TUBES USED IN ULTRASUPERCRTICAL BOILERS UPON THE TUBES' STEAM OXIDATION BEHAVIOR

通过对一组运行了4年的不锈钢过热器管样内表面机加工区和非机加工区氧化皮的结构和形貌特征进行对比分析,探讨内表面冷作硬化处理对于超超临界机组锅炉用不锈钢管蒸汽氧化性能的影响。结果表明,内表面冷作硬化处理对于改善细晶TP347HFG和Super304奥氏体不锈钢在相对较低温度蒸汽中的抗氧化性能非常有效,但在600℃左右高温蒸汽中Super304管样内表面冷作硬化效应消失,除冷作硬化试样氧化皮的总体厚度略薄外,氧化皮的结构形貌特征与未冷作硬化处理的管样没有多大区别。另外,含Cr量大于22%的SAVE25具有非常优秀的抗蒸汽氧化性能,其机加工区域和未机加工区域的蒸汽氧化行为没有任何区别。

The influence of cold work hardening inner surface of austenitic stainless steel tubes used in ultra - supercritical boilers upon the tubes＇ steam oxidataion behavior has been discussed after comparative analysis of microstructure and form - appearance features of steam oxidation scale formed on the machined area and non-machined area on the inner surface of tube spcimens taken from superheater tubes which had already been in operation for 4 years. The results show that the cold work hardening inner surface is very effective to improve the steam oxidation resisting behavior of TO347HFG and Super 304 fined grain austenitic stainless steel under relatively lower temperature, but the effect of cold work hardening inner surface upon Super 304 steel disappeared entirely in high - temperature steam of about 600℃, excepting the scale thickness is slightly thiner,there is little difference of microstructure and formappearance features between tube specimens with cold work hardening inner surface and that without cold work hardening inner surface. In addition, the steam oxidation resisting behavior of SAVE 24 steel,whose Cr content is more than 22%, is very excellent, there isn＇t any difference of steam oxidation behavior on the machined area and the non - machnied area of the tested tube specimens.