Characterization of microstructure of HAZs in as-welded and service condition of P91 pipe weldments
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- 作者：C. Pandey ; A. Giri ; M. M. Mahapatra ; P. Kumar
- 关键词：tempering ; grain boundary ; toughness ; microstructure ; scanning electron microscopy (SEM)
- 刊名：Metals and Materials International
- 出版年：2017
- 出版时间：January 2017
- 年：2017
- 卷：23
- 期：1
- 页码：148-162
- 全文大小：
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Metallic Materials; Operating Procedures, Materials Treatment; Magnetism, Magnetic Materials; Engineering Thermodynamics, Heat and Mass Transfer; Characterization and Evaluation of Materials; Continuu
- 出版者：The Korean Institute of Metals and Materials
- ISSN：2005-4149
- 卷排序：23
文摘
Steels 9-12% Cr, having the high creep rupture strength are advocated for the modern low polluting thermal power plants. In the present investigation, the P91 pipe weldments have been characterized for microstructural responses in as-welded, post-weld heat treatment (PWHT) and ageing conditions. The PWHT of welded samples were carried out at 760 °C for time of 2 h and ageing at 760 °C for 720 h and 1440 h, respectively. The effect of time has been studied on precipitates size, distribution of precipitates and grain sizes present in various zones of P91 steel weldments. The impact toughness and hardness variation of heat affected zone (HAZ) have also been studied in as-welded condition as well as at different heat treatment condition. A significant change was observed in grain size and precipitates size after each heat treatment condition. The maximum impact toughness of HAZ was obtained after PWHT at 760 °C for 2 h. The main phase observed in weld fusion zone in as-welded, PWHT and ageing conditions were M<sub>23sub>C<sub>6sub>, MX, M<sub>7sub>C<sub>3sub>, Fe-rich M<sub>3sub>C and M<sub>2sub>C. The unwanted Z-phase (NbCrN) was also noticed in weld fusion zone after ageing of 1440 h.