{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,13]],"date-time":"2025-12-13T07:23:07Z","timestamp":1765610587834,"version":"build-2065373602"},"reference-count":33,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T00:00:00Z","timestamp":1739318400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100010880","name":"Technology Project of State Grid Corporation of China","doi-asserted-by":"publisher","award":["0FW-221141-JS"],"award-info":[{"award-number":["0FW-221141-JS"]}],"id":[{"id":"10.13039\/501100010880","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>The main steam pipe elbow is a critical metallic component in thermal power plants. Due to prolonged exposure to high temperatures and pressures, it experiences microstructural degradation and creep damage, thereby affecting its service life. Currently, there is debate regarding the location of the weakest region within the elbow, with uncertainty over whether it lies in the inner arc or neutral plane area. This study investigates the microstructure and creep properties of both the inner arc and neutral surface regions of an elbow that has been in operation for 183,088 h, aiming to identify the actual weak region and explore the underlying creep damage mechanisms. The results indicate that under identical temperature and stress conditions, samples from the neutral plane region exhibit significantly higher creep rates and shorter creep rupture times compared to those from the inner arc region. This suggests that the creep life in the vicinity of the inner surface in the neutral plane is markedly lower than that in the inner arc region. Microstructural analysis before and after creep fracture reveals that key factors influencing the creep performance of 12Cr1MoV elbows include carbide size, precipitation amount and distribution, grain size and morphology, as well as the stability and uniformity of grain orientation. Specifically, the growth of intragranular precipitates, the accumulation and non-uniform distribution of grain boundary carbides, and the non-uniform distribution of grain sizes all contribute to the rapid formation of creep cracks and premature material failure. This study concludes that the weakest region in the elbow is located at the inner surfaces of the neutral plane. Future inspections and life assessments of thermal power plant elbows should therefore focus on this area to enhance the accuracy of life evaluations and ensure the safety of thermal power plants.<\/jats:p>","DOI":"10.3390\/ma18040812","type":"journal-article","created":{"date-parts":[[2025,2,12]],"date-time":"2025-02-12T12:12:16Z","timestamp":1739362336000},"page":"812","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Creep Failure Behavior in the Weak Areas of 12Cr1MoV Main Steam Pipe Elbow Utilized in Thermal Power Plants"],"prefix":"10.3390","volume":"18","author":[{"given":"Shutao","family":"Wang","sequence":"first","affiliation":[{"name":"Jiangsu Frontier Electric Power Technology Co., Ltd., Nanjing 211100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Renqiang","family":"Shi","sequence":"additional","affiliation":[{"name":"Jiangsu Frontier Electric Power Technology Co., Ltd., Nanjing 211100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jian","family":"Wu","sequence":"additional","affiliation":[{"name":"College of Materials Science and Engineering, Hohai University, Changzhou 213200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Chao","family":"Yang","sequence":"additional","affiliation":[{"name":"Jiangsu Frontier Electric Power Technology Co., Ltd., Nanjing 211100, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1138-4380","authenticated-orcid":false,"given":"Huan","family":"Liu","sequence":"additional","affiliation":[{"name":"College of Materials Science and Engineering, Hohai University, Changzhou 213200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5225","DOI":"10.1016\/j.jmrt.2024.02.187","article-title":"Finite Element Modeling and Experimental Investigation on Manufacturing TA18 Alloy Pipes via Hot Free Bending Forming Technology: Forming Characteristics and Process Optimization","volume":"29","author":"Cheng","year":"2024","journal-title":"J. Mater. Res. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"358","DOI":"10.1016\/j.flowmeasinst.2008.05.005","article-title":"Measurement of the Fluid Flow Rate with Use of an Elbow with Oval Cross Section","volume":"19","author":"Malinowski","year":"2008","journal-title":"Flow Meas. Instrum."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"498","DOI":"10.1016\/j.phpro.2012.05.095","article-title":"Comparison of Two Methods of Finite Element Modeling for Elbows with Unequal Wall Thickness","volume":"33","author":"Dong","year":"2012","journal-title":"Phys. Procedia"},{"key":"ref_4","unstructured":"Ye, S.C., Zhang, H.J., Guo, Y.J., Xiao, K.R., Jiang, Y.M., and Li, H.Y. (2023). Stress Analysis of Unequal-wall-thickness P92 Elbow. Chem. Eng. Equip., 174\u2013176. (In Chinese)."},{"key":"ref_5","first-page":"24","article-title":"Stress Analysis of Non-circular Section Elbow under Internal Pressure","volume":"22","author":"An","year":"2001","journal-title":"Electr. Power Constr."},{"key":"ref_6","first-page":"224","article-title":"Stress Analysis of Non-circular Section Pipe Components under Pressure Load","volume":"48","author":"Li","year":"2021","journal-title":"Chem. Process Mach."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"022061","DOI":"10.1088\/1757-899X\/612\/2\/022061","article-title":"Failure Analysis on 12cr1mov Steel Tube of High Temperature Reheater for 600 Mw Subcritical Boiler","volume":"612","author":"Wang","year":"2019","journal-title":"IOP Conf. Ser. Mater. Sci. Eng."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"7095872","DOI":"10.1155\/2020\/7095872","article-title":"Study on Tensile Creep Behavior of 12Cr1MoV Alloy Steel under High-Temperature Alkali Metal Salt Environment for Solar Thermal Power Generation","volume":"2020","author":"He","year":"2020","journal-title":"Int. J. Photoenergy"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"012013","DOI":"10.1088\/1757-899X\/1040\/1\/012013","article-title":"Structural Changes of 12Cr1MoVG Steel during High-Temperature Creep","volume":"1040","author":"Pan","year":"2021","journal-title":"IOP Conf. Ser. Mater. Sci. Eng."},{"key":"ref_10","doi-asserted-by":"crossref","unstructured":"Liu, J., and Li, Y. (2022). Influence of 12Cr1MoV Material on Tissue Properties at High Temperature and Long Operating Time. Processes, 10.","DOI":"10.3390\/pr10020192"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"012193","DOI":"10.1088\/1755-1315\/675\/1\/012193","article-title":"Residual Life Evaluation of 12Cr1MoVG Steel for Main Steam Pipeline","volume":"675","author":"Tang","year":"2021","journal-title":"IOP Conf. Ser. Earth Environ. Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"617","DOI":"10.1080\/09603409.2016.1204063","article-title":"Experimental Observation of Creep Damage Evolution in Seam-Welded Elbows of Mod. 9Cr-1Mo Steel","volume":"33","author":"Komai","year":"2016","journal-title":"Mater. High Temp."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"436","DOI":"10.1007\/s40430-020-02521-0","article-title":"The Ratcheting Behavior of Carbon Steel Piping Elbows under Cyclic Bending Moment and Temperature","volume":"42","author":"Zakavi","year":"2020","journal-title":"J. Braz. Soc. Mech. Sci. Eng."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"320","DOI":"10.1016\/j.engfailanal.2017.08.007","article-title":"Testing and Assessment of Cracking in P91 Steels under Creep-Fatigue Loading Conditions","volume":"84","author":"Davies","year":"2018","journal-title":"Eng. Fail. Anal."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"343","DOI":"10.1007\/s12540-018-0192-6","article-title":"Microstructural Degradation and Creep Fracture Behavior of Conventionally and Thermomechanically Treated 9% Chromium Heat Resistant Steel","volume":"25","author":"Vivas","year":"2019","journal-title":"Met. Mater. Int."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2351","DOI":"10.1016\/j.jmps.2007.03.019","article-title":"Modeling the Microstructural Evolution of Metallic Polycrystalline Materials under Localization Conditions","volume":"55","author":"Bronkhorst","year":"2007","journal-title":"J. Mech. Phys. Solids"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1016\/j.proeng.2013.03.325","article-title":"Modeling the Effect of Grain Boundary Sliding on Creep Lifetime: Application to Two Austenitic Stainless Steels","volume":"55","author":"Mahesh","year":"2013","journal-title":"Procedia Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"106715","DOI":"10.1016\/j.ijmecsci.2021.106715","article-title":"Evaluation of Local Stress State Due to Grain-Boundary Sliding during Creep within a Crystal Plasticity Finite Element Multi-Scale Framework","volume":"211","author":"Petkov","year":"2021","journal-title":"Int. J. Mech. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"5833","DOI":"10.1016\/j.jmrt.2019.09.053","article-title":"Effect of Carbides on High-Temperature Aging Embrittlement in 12%Cr Martensitic Heat-Resistant Steel","volume":"8","author":"Li","year":"2019","journal-title":"J. Mater. Res. Technol."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"7883","DOI":"10.1007\/s10853-020-04537-2","article-title":"Relationship between Carbon Segregation and the Carbide Precipitation along Grain Boundary Based on the Structural Plant Model","volume":"55","author":"Cao","year":"2020","journal-title":"J. Mater. Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"4424","DOI":"10.1016\/j.jmrt.2024.04.161","article-title":"Thermal Stability of Ni-Based Superalloys Fabricated through Additive Manufacturing: A Review","volume":"30","author":"Hamdi","year":"2024","journal-title":"J. Mater. Res. Technol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"191","DOI":"10.1016\/S0921-5093(03)00517-3","article-title":"Formation of Carbides and Their Effects on Stress Rupture of a Ni-Base Single Crystal Superalloy","volume":"361","author":"Liu","year":"2003","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"145116","DOI":"10.1016\/j.msea.2023.145116","article-title":"The Effect of Carbides on the Creep Performance of Hastelloy X Fabricated by Laser Powder Bed Fusion","volume":"875","author":"Wu","year":"2023","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1016\/j.jmst.2021.03.022","article-title":"Effect of Grain Boundary Precipitates on the Stress Rupture Properties of K4750 Alloy after Long-Term Aging at 750 \u00b0C for 8000 h","volume":"92","author":"Ou","year":"2021","journal-title":"J. Mater. Sci. Technol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2018","DOI":"10.1016\/j.jmrt.2022.05.194","article-title":"Effect of Phosphorus Segregation on Carbides and Creep Damage of Ni\u2013Fe-Based GH984G Alloy","volume":"19","author":"Zhang","year":"2022","journal-title":"J. Mater. Res. Technol."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"159016","DOI":"10.1016\/j.jallcom.2021.159016","article-title":"Raising Thermal Stability of Nanograins in a CuCrZr Alloy by Precipitates on Grain Boundaries","volume":"867","author":"Zhang","year":"2021","journal-title":"J. Alloys Compd."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"2443","DOI":"10.1016\/j.actamat.2006.11.039","article-title":"A Quantitative Analysis of the Influence of Carbides Size Distributions on Wear Behaviour of High-Speed Steel in Dry Rolling\/Sliding Contact","volume":"55","author":"Rodenburg","year":"2007","journal-title":"Acta Mater."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.jnucmat.2007.07.013","article-title":"Modelling Precipitate Distribution in Reduced-Activation Steels","volume":"374","year":"2008","journal-title":"J. Nucl. Mater."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"231","DOI":"10.1016\/j.msea.2006.08.116","article-title":"Grain-Size Distribution Effects in Plastic Flow and Failure","volume":"463","author":"Phaniraj","year":"2007","journal-title":"Mater. Sci. Eng. A"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"51","DOI":"10.1016\/S1359-6462(02)00096-9","article-title":"Triple Junction Diffusion and Plastic Flow in Fine-Grained Materials","volume":"47","author":"Fedorov","year":"2002","journal-title":"Scr. Mater."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2998","DOI":"10.1007\/s11837-019-03557-x","article-title":"Creep Behaviors Along Characteristic Crystal Orientations of Sn and Sn-1.8Ag by Using Nanoindentation","volume":"71","author":"Chiang","year":"2019","journal-title":"JOM"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2434","DOI":"10.1557\/s43578-021-00165-x","article-title":"Effects of Crystal Orientation on the Indentation Creep of \u03b2-Tin","volume":"36","author":"Liang","year":"2021","journal-title":"J. Mater. Res."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"265","DOI":"10.1016\/j.jmst.2020.10.021","article-title":"Orientation Dependent Behavior of Tensile-Creep Deformation of Hot Rolled Ti65 Titanium Alloy Sheet","volume":"75","author":"Zhang","year":"2021","journal-title":"J. Mater. Sci. Technol."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/4\/812\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T16:32:26Z","timestamp":1760027546000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/18\/4\/812"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,2,12]]},"references-count":33,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2025,2]]}},"alternative-id":["ma18040812"],"URL":"https:\/\/doi.org\/10.3390\/ma18040812","relation":{},"ISSN":["1996-1944"],"issn-type":[{"type":"electronic","value":"1996-1944"}],"subject":[],"published":{"date-parts":[[2025,2,12]]}}}