Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness
Appropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat...
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doaj-0db5d374ceb742a8a21a025ee7537f942020-11-25T02:30:43ZengMDPI AGMetals2075-47012020-09-01101215121510.3390/met10091215Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact ToughnessGorazd Lojen0Tomaž Vuherer1Faculty of mechanical engineering, University of Maribor, Smetanova ulica 17, 2000 Maribor, SloveniaFaculty of mechanical engineering, University of Maribor, Smetanova ulica 17, 2000 Maribor, SloveniaAppropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat affected zone (HAZ) subzones was studied. Thereby, coarse grained HAZ, two different fine grained HAZ areas, and intercritical HAZ were subjected to 20 different PWHTs at temperatures 740–800 °C and durations 0.5–8 h. It was found that the most commonly recommended PWHT, of 3 h or less at 760 °C, is insufficient with respect to the hardness and impact toughness of coarse grained HAZ. To obtain a Vickers hardness ≤ 265 <i>HV</i> and impact toughness at least equal to the impact toughness of the base metal (192 J) in the coarse grained HAZ, it took 8 h at 740 °C, 4 h at 760 °C, more than 1 h at 780 °C, and 0.5 h and 800 °C. Even after 8 h at 800 °C, mechanical properties were still within the target range. The most recommendable post weld heat treatments at 780 °C for 1.2–2 h or at 760 °C for 3–4 h were identified. All specimens subjected to these treatments exhibited appropriate hardness, impact toughness, and microstructure.https://www.mdpi.com/2075-4701/10/9/1215post weld heat treatmentHAZ subzone simulationimpact toughnesscrack initiation energycrack propagation energy. |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Gorazd Lojen Tomaž Vuherer |
spellingShingle |
Gorazd Lojen Tomaž Vuherer Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness Metals post weld heat treatment HAZ subzone simulation impact toughness crack initiation energy crack propagation energy. |
author_facet |
Gorazd Lojen Tomaž Vuherer |
author_sort |
Gorazd Lojen |
title |
Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness |
title_short |
Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness |
title_full |
Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness |
title_fullStr |
Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness |
title_full_unstemmed |
Optimization of PWHT of Simulated HAZ Subzones in P91 Steel with Respect to Hardness and Impact Toughness |
title_sort |
optimization of pwht of simulated haz subzones in p91 steel with respect to hardness and impact toughness |
publisher |
MDPI AG |
series |
Metals |
issn |
2075-4701 |
publishDate |
2020-09-01 |
description |
Appropriate post weld heat treatment (PWHT) is usually obligatory when creep resistant steels are welded for thermal power plant components that operate at elevated temperatures for 30-40 years. The influence of different PWHTs on the microstructure, hardness, and impact toughness of simulated heat affected zone (HAZ) subzones was studied. Thereby, coarse grained HAZ, two different fine grained HAZ areas, and intercritical HAZ were subjected to 20 different PWHTs at temperatures 740–800 °C and durations 0.5–8 h. It was found that the most commonly recommended PWHT, of 3 h or less at 760 °C, is insufficient with respect to the hardness and impact toughness of coarse grained HAZ. To obtain a Vickers hardness ≤ 265 <i>HV</i> and impact toughness at least equal to the impact toughness of the base metal (192 J) in the coarse grained HAZ, it took 8 h at 740 °C, 4 h at 760 °C, more than 1 h at 780 °C, and 0.5 h and 800 °C. Even after 8 h at 800 °C, mechanical properties were still within the target range. The most recommendable post weld heat treatments at 780 °C for 1.2–2 h or at 760 °C for 3–4 h were identified. All specimens subjected to these treatments exhibited appropriate hardness, impact toughness, and microstructure. |
topic |
post weld heat treatment HAZ subzone simulation impact toughness crack initiation energy crack propagation energy. |
url |
https://www.mdpi.com/2075-4701/10/9/1215 |
work_keys_str_mv |
AT gorazdlojen optimizationofpwhtofsimulatedhazsubzonesinp91steelwithrespecttohardnessandimpacttoughness AT tomazvuherer optimizationofpwhtofsimulatedhazsubzonesinp91steelwithrespecttohardnessandimpacttoughness |
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