長期高溫服役后HP40Nb鋼爐管的組織及剩余壽命

長期高溫服役后HP40Nb鋼爐管的組織及剩余壽命Structure and Remnant Life of HP40Nb Steel Furnace Tube after Long-Term High-Temperature Service

利用光學顯微鏡、掃描電鏡、能譜儀、拉伸及沖擊試驗機等對服役15 a的制氫轉(zhuǎn)化爐中HP40Nb鋼爐管的顯微組織和力學性能進行了研究，依據(jù)高溫持久試驗結(jié)果估算了爐管剩余壽命。結(jié)果表明：長期高溫服役后，爐管鋼組織中晶界粗化并有G相析出，晶內(nèi)二次碳化物析出明顯，近內(nèi)壁、近外壁和基體中均出現(xiàn)蠕變孔洞，近內(nèi)壁和近外壁發(fā)生氧化和貧鉻，外壁形成脫碳層；與原始鑄態(tài)爐管相比，長期高溫服役后爐管的室溫抗拉強度降幅超30%，高溫抗拉強度降幅約18%，室溫沖擊功下降明顯，剩余壽命不足1 a。

The microstructure and mechanical properties of HP40Nb steel furnace tube in a hydrogen reformer after 15-year service were studied by optical microscope, scanning electron microscope, energy dispersive spectrometer, tensile and impact testers. Based on the high-temperature creep rupture testing results, the remnant life of the furnace tube was evaluated. The results show that after the long-term high-temperature service, in the microstructure of furnace tube steel, the grain boundaries coarsened with the G phase precipitation; secondary carbides precipitated in grains obviously; creep voids were observed near inner and outer wall and in matrix; oxidation and chromium depletion were observed near inner and outer wall; decarburization layer was formed on the outer wall. Compared with the as-cast steel furnace tube, the tensile strength of the furnace tube after the long-term high-temperature service reduced by 30% and 18% at room and high temperature, respectively, the impact energy at room temperature decreased significantly, and the remnant life was less than 1 a.

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