SHI Zhigang, MA Hong, CUI Xionghua, et al. Mechanical properties and microstructure transformation of T23 and T91 superheater tubes failed by short-term overheating[J]. Thermal power generation, 2014, 43(9): 129-132.
SHI Zhigang, MA Hong, CUI Xionghua, et al. Mechanical properties and microstructure transformation of T23 and T91 superheater tubes failed by short-term overheating[J]. Thermal power generation, 2014, 43(9): 129-132.DOI:
T23和T91高温过热器短时超温爆管的组织性能分析
摘要
某亚临界700MW机组锅炉T23和T91高温过热器服役近105 h时
发生短时超温爆管。为此
对其组织性能进行了试验。发现:T23微观组织明显异常
为铁素体+无位向碳化物
抗拉强度和硬度略有升高
而规定塑性延伸强度(Rp)却显著降低;T91微观组织略有变化
为细碎马氏体+微量碳化物
抗拉强度和硬度显著升高。研究表明
铁素体耐热钢制高温过热器短时超温爆管后
决定其相变后组织形态的主要因素是其随炉冷却速率
并非爆管后所喷射出的工质冷却速率。
Abstract
Several T23 and T91 steel superheater tubes in a subcritical pressure 700 MW unit boiler had failed for short-term overheating after serving for 105 h.The mechanical properties and microstructure of the failed tubes were studied.The results show that there was an obvious change of microstructure for the failed T23 steel
whose microstructure was made of ferrite and no-orientation carbide.Its tensile strength and hardness increased weakly
while its proof strength of non-proportional elongation(Rp)decreased dramatically.The results for T91 went the opposite way
with a slight change of microstructure and a significant rise of tensile strength and hardness.It indicates that the factor determining the microstructure of failed superheater tubes made by ferrite high temperature-resistance steel is the cooling rate of furtance