Long-term Creep Strength and Fracture of 9Cr Steel Welds
Mod.9Cr-lMo steel (ASME Gr.91 steel) is widely used as a main structural material for boiler components in ultra-supercritieal (USC) thermal power plant at 600 ℃.The decrease of creep strength of welded joint due to Type-Ⅳ failure is a critical issue, however long-term creep rupture data over 10,000 h was scarcely obtained.The present paper conducted long-term creep tests over 10,000h for Gr.91 steel welded joints at 600 and 650 ℃.For the specimens fractured for about 35,000 h at 600 and 650 ℃, creep damages were mainly observed in HAZ (Type-Ⅳ),however they were also observed in the weld metal.The welded joint crept for 600 ℃ and 50 MPa for about 55,000h was fractured in weld metal.It was found that the hardness of 9Cr weld metal decreased after about 30,000 h creep at 600 ℃ due to the recovery of microstructures.Therefore it is considered to be necessary to monitor creep damage not only in HAZ but also in weld metal.
Gr.91 steel Welded joint Long-term creep Type-Ⅳfailure Weld metal
Hiromichi Hongo Tetsuya Matsunaga Masaaki Tabuchi
National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan
国际会议
长沙
英文
172-176
2016-10-16（万方平台首次上网日期，不代表论文的发表时间）