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。
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,but not the cooling rate of ejected fluid.
出处
《热力发电》
CAS
北大核心
2014年第9期129-132,共4页
Thermal Power Generation
关键词
T23
T91
高温过热器
短时超温
爆管
微观组织
组织性能
T23
T91
high temperature
superheater
shot-time over heating
tube buest
microstructure
mechanical properties
