应用金相扫描电镜、透射电镜和X 射线衍射等分析技术,研究了电站锅炉用 TP304H不锈钢管显微组织老化的主要特征,明确了σ析出相含量与管子寿命的定量关系。结果表明:一定的压力条件下,TP304H 钢管的显微组织变化与运行温度和时间相关,在设计温度下,随着运行时间的延长,TP304H 钢管晶界开始析出呈链状分布的碳化物,继续运行σ相开始沿晶界(特别是三角晶界处)析出;当σ相含量达到15%时,爆管几乎不可避免,因此,可以采用定量分析方法通过测定σ相含量来监测 TP304H 钢管的寿命。

The microstructure degradation characteristics of TP304Hstainless steel tubes used in power plantboilers were studied by means of optical microscope,scanning electron microscope,transmission electron microscopeand X-ray diffractometer,and the relationships between theσ-phase content and the life of the tubes were alsogiven.The results show that under constant pressure,the microstructure transformation of TP304H tubescorrelated with operating temperature and time,and as the operating time lasting,chain-like carbides wouldprecipitate along grain boundaries at the design temperature and σ-phase would also precipitate along grainboundaries,especially in triangle ones.Tube bursting must happen if the totalσ-phase content reached 15%,soquantitative method can be used to supervise the life of TP304Htubes by measuring theσ-phase content.