文献类型：期刊文献

英文题名：Effect of aging at 700°C on precipitation and toughness of AISI 321 and AISI 347 austenitic stainless steel welds

作者：Guan, Kaishu[1]; Xu, Xiaodong[2]; Xu, Hong[1]; Wang, Zhiwen[1]

机构：[1]E China Univ Sci & Technol, Res Inst Proc Equipment & Pressure Vessel, Shanghai 200237, Peoples R China;[2]Sinopec Corp, Jinan Co, Jinan 250101, Peoples R China

年份：2005

卷号：235

期号：23

起止页码：2485

外文期刊名：NUCLEAR ENGINEERING AND DESIGN

收录：;EI(收录号：2005469474576);WOS:【SCI-EXPANDED(收录号:WOS:000233503500004)】；

语种：英文

外文关键词：Aging of materials - Fractography - Microstructure - Precipitation (chemical) - Terbium - Toughness - Welding

摘要：A detailed knowledge of changes in microstructures and mechanical behaviour that occur in austenitic stainless steels with or without Nb/Ti-stabilized weld during heat treatment is of great interest, since the ductility and toughness of the material may change drastically after long aging times. Two kinds of materials, i.e. AISI 321 base and without Ti-stabilized weld steel and AISI 347 base with Nb-stabilized weld steel, were compared during aging at 700 degrees C up to 6000h. Both materials present increased amount of precipitate and decreased impact energy as the aging time increases. The decreased extent of impact energy with aging is almost the same for both base materials. However, it presents differences for 347 and 321 weld samples. The latter shows a more drastic decrease of impact energy than the former due to the different amount of precipitates. 321 weld sample precipitates more numerously than 347 weld sample due to the absence of stabilized Ti/Nb on the former. Large amount of carbides is formed on 321 weld sample immediately after welding. The carbides are transformed to sigma phase, which is mainly responsible for the much more sigma phase precipitation compared with other samples, after high-temperature aging. The fractographs showed, in general, brittle fracture mode in 321 weld impact-fractured specimens after aging at 700 degrees C for 6000 h. However, other samples show ductile fracture mode in general. Several approaches should be employed to control sigma phase precipitation in weld material. These approaches include: decreasing content of ferrite and M23C6 carbide in weld and selecting Nb added weld wire during welding. (c) 2005 Elsevier B.V. All rights reserved.