Pub Date : 2026-01-08DOI: 10.1016/j.ijpvp.2025.105743
A. Oñate , J. Ramirez , G. Dueña , M. Melendrez , C. Lanziotti , R. Apablaza , D. Rojas
This study investigated the premature failure of a welded 2205 duplex stainless steel tube operating in a black liquor heat exchanger at a pulp and paper plant. Although the component was designed for a ten-year service life, failure occurred after only two years, with macroscopic evidence of pitting corrosion aligned along the longitudinal weld. Metallographic examination revealed localized attack progressing intergranularly between ferrite and austenite. SEM-EDS analysis identified pronounced Cr, Mo, and Ni segregation near the weld bead, while XRD combined with Rietveld refinement quantified approximately 3.6 wt% sigma phase in the weld/HAZ region. As a consequence of these welding-induced microstructural changes, electrochemical tests in 0.6 M NaCl showed metastable passivity and higher current densities in the weld zone. Under alkaline conditions at 65 °C, the welded joint exhibited a reduction in corrosion resistance compared with the base metal. The modeled TTT-CCT diagram for the alloy composition supported the experimental observations, indicating that the welding thermal cycle intersected the sigma-forming region. Overall, the results demonstrate that thermal exposure during welding promoted elemental segregation and sigma-phase nucleation, creating galvanic microcells that facilitated localized corrosion and intergranular propagation. These findings underscore the need for stricter thermal control and post-fabrication verification of welded 2205 duplex stainless steel components operating in high-temperature, high-pH environments.
本研究调查了在纸浆和造纸厂黑液热交换器中工作的2205双相不锈钢焊接管的过早失效。尽管该组件的设计使用寿命为10年，但仅在两年后就发生了故障，在纵向焊缝上出现了宏观的点蚀迹象。金相检查显示铁素体和奥氏体之间的局部攻击在晶间进展。SEM-EDS分析发现焊缝附近存在明显的Cr、Mo和Ni偏析，而XRD结合Rietveld精细化分析发现焊缝/HAZ区域约有3.6 wt%的sigma相。由于这些焊接引起的微观结构变化，在0.6 M NaCl中进行电化学测试，焊缝区显示出亚稳钝化和更高的电流密度。在65℃的碱性条件下，与母材相比，焊接接头的耐腐蚀性降低。模拟的合金成分TTT-CCT图与实验结果相吻合，表明焊接热循环与sigma形成区相交。总的来说，结果表明，焊接过程中的热暴露促进了元素偏析和sigma相成核，产生了有利于局部腐蚀和晶间扩展的原电微细胞。这些发现强调了在高温、高ph值环境下工作的焊接2205双相不锈钢部件需要更严格的热控制和制造后验证。
{"title":"Failure analysis of a 2205 duplex stainless steel tube affected by localized corrosion in a black liquor heat exchanger","authors":"A. Oñate , J. Ramirez , G. Dueña , M. Melendrez , C. Lanziotti , R. Apablaza , D. Rojas","doi":"10.1016/j.ijpvp.2025.105743","DOIUrl":"10.1016/j.ijpvp.2025.105743","url":null,"abstract":"<div><div>This study investigated the premature failure of a welded 2205 duplex stainless steel tube operating in a black liquor heat exchanger at a pulp and paper plant. Although the component was designed for a ten-year service life, failure occurred after only two years, with macroscopic evidence of pitting corrosion aligned along the longitudinal weld. Metallographic examination revealed localized attack progressing intergranularly between ferrite and austenite. SEM-EDS analysis identified pronounced Cr, Mo, and Ni segregation near the weld bead, while XRD combined with Rietveld refinement quantified approximately 3.6 wt% sigma phase in the weld/HAZ region. As a consequence of these welding-induced microstructural changes, electrochemical tests in 0.6 M NaCl showed metastable passivity and higher current densities in the weld zone. Under alkaline conditions at 65 °C, the welded joint exhibited a reduction in corrosion resistance compared with the base metal. The modeled TTT-CCT diagram for the alloy composition supported the experimental observations, indicating that the welding thermal cycle intersected the sigma-forming region. Overall, the results demonstrate that thermal exposure during welding promoted elemental segregation and sigma-phase nucleation, creating galvanic microcells that facilitated localized corrosion and intergranular propagation. These findings underscore the need for stricter thermal control and post-fabrication verification of welded 2205 duplex stainless steel components operating in high-temperature, high-pH environments.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105743"},"PeriodicalIF":3.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.ijpvp.2026.105757
Tomoki Shinko , Naoki Miura , Masaki Nagai
For the long-term operation of a nuclear reactor, it is important to effectively use the limited number of surveillance test specimens for conducting additional surveillance tests. One of the expected solutions is the use of miniature C(T) (Mini-C(T)) specimens which can be fabricated from broken Charpy specimens. However, it is known that the evaluation of J-R curves using Mini-C(T) specimens may be affected by the difference in plastic constraint due to the specimen size. In this paper, a novel methodology of specimen size effect correction in J-R curve evaluation based on a bending-modified plastic constraint parameter QM has been proposed. To verify the applicability of the proposed method to Mini-C(T) specimen in RPV steels, the J-R tests on the two Japanese RPV steels SQV2A with different fracture toughness levels were conducted using Mini-C(T), 0.5T-C(T), and 1T-C(T) specimens. As a result of the tests, a specimen size effect of Mini-C(T) specimen on J-R curve was found in the SQV2A with higher fracture toughness. To calculate QM, finite element method analysis has been performed to estimate the crack opening stress distribution ahead of the crack tip during the test. QM increased with increasing normalized J-integral. Based on the relationship between QM and normalized J-integral, the proposed method successfully reduced the specimen size effect on the J-R curve of the tested materials. The proposed method is expected to be useful in case of a limited amount of material such as surveillance specimens because the method requires no tests other than Mini-C(T) specimen testing.
{"title":"Novel methodology of specimen size effect correction in J-R curve evaluation based on bending-modified Q parameter","authors":"Tomoki Shinko , Naoki Miura , Masaki Nagai","doi":"10.1016/j.ijpvp.2026.105757","DOIUrl":"10.1016/j.ijpvp.2026.105757","url":null,"abstract":"<div><div>For the long-term operation of a nuclear reactor, it is important to effectively use the limited number of surveillance test specimens for conducting additional surveillance tests. One of the expected solutions is the use of miniature C(T) (Mini-C(T)) specimens which can be fabricated from broken Charpy specimens. However, it is known that the evaluation of J-R curves using Mini-C(T) specimens may be affected by the difference in plastic constraint due to the specimen size. In this paper, a novel methodology of specimen size effect correction in J-R curve evaluation based on a bending-modified plastic constraint parameter <em>Q</em><sub><em>M</em></sub> has been proposed. To verify the applicability of the proposed method to Mini-C(T) specimen in RPV steels, the J-R tests on the two Japanese RPV steels SQV2A with different fracture toughness levels were conducted using Mini-C(T), 0.5T-C(T), and 1T-C(T) specimens. As a result of the tests, a specimen size effect of Mini-C(T) specimen on J-R curve was found in the SQV2A with higher fracture toughness. To calculate <em>Q</em><sub><em>M</em></sub>, finite element method analysis has been performed to estimate the crack opening stress distribution ahead of the crack tip during the test. <em>Q</em><sub><em>M</em></sub> increased with increasing normalized J-integral. Based on the relationship between <em>Q</em><sub><em>M</em></sub> and normalized J-integral, the proposed method successfully reduced the specimen size effect on the J-R curve of the tested materials. The proposed method is expected to be useful in case of a limited amount of material such as surveillance specimens because the method requires no tests other than Mini-C(T) specimen testing.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105757"},"PeriodicalIF":3.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928211","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-08DOI: 10.1016/j.ijpvp.2026.105752
Dorina Siebert, Elena Maier, Christina Radlbeck, Martin Mensinger
The cover plate is a common structural detail in railway bridges, and its welds are particularly susceptible to fatigue cracking. This study investigates the fracture mechanics of cover plate welds, focusing on the stress intensity factor and geometry correction factor through numerical simulations. A simple plate model with a semi-elliptical surface crack is first used for validation, with a maximum deviation of about 4 %, confirming the accuracy of the finite element analysis. A comprehensive parametric study is then performed for two configurations: a cover plate detail without a web and a cover plate detail with a web. Key geometric parameters are systematically analyzed. The results show that smaller width and thickness ratios increase the stress intensity factors, making these configurations more critical for fatigue. Additionally, steeper weld slopes (1:2) result in higher stress intensities than shallower slopes (1:3), which are more favorable. The inclusion of a web significantly increases the geometry correction factor, resulting in higher crack propagation rates. The web restricts base plate bending and compressive stress relief at the weld toe, resulting in stress intensity increases of up to 63 % (1:2 slope) and 40 % (1:3 slope). Comparison with literature formulas shows that the FEA-based results of this study yield lower correction factors, suggesting that current design formulas may be conservative. To support practical applications, regression formulas for the geometry correction factor are developed that achieve high accuracy (R2 ≥ 0.9774) and provide a more accurate basis for fatigue assessment in welded cover plate details.
{"title":"Numerical investigation of stress intensity and geometry correction factors in welded cover plate details","authors":"Dorina Siebert, Elena Maier, Christina Radlbeck, Martin Mensinger","doi":"10.1016/j.ijpvp.2026.105752","DOIUrl":"10.1016/j.ijpvp.2026.105752","url":null,"abstract":"<div><div>The cover plate is a common structural detail in railway bridges, and its welds are particularly susceptible to fatigue cracking. This study investigates the fracture mechanics of cover plate welds, focusing on the stress intensity factor and geometry correction factor through numerical simulations. A simple plate model with a semi-elliptical surface crack is first used for validation, with a maximum deviation of about 4 %, confirming the accuracy of the finite element analysis. A comprehensive parametric study is then performed for two configurations: a cover plate detail without a web and a cover plate detail with a web. Key geometric parameters are systematically analyzed. The results show that smaller width and thickness ratios increase the stress intensity factors, making these configurations more critical for fatigue. Additionally, steeper weld slopes (1:2) result in higher stress intensities than shallower slopes (1:3), which are more favorable. The inclusion of a web significantly increases the geometry correction factor, resulting in higher crack propagation rates. The web restricts base plate bending and compressive stress relief at the weld toe, resulting in stress intensity increases of up to 63 % (1:2 slope) and 40 % (1:3 slope). Comparison with literature formulas shows that the FEA-based results of this study yield lower correction factors, suggesting that current design formulas may be conservative. To support practical applications, regression formulas for the geometry correction factor are developed that achieve high accuracy (R<sup>2</sup> ≥ 0.9774) and provide a more accurate basis for fatigue assessment in welded cover plate details.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105752"},"PeriodicalIF":3.5,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, the evolution of localized pitting and intergranular corrosion (IGC) of 2195-T8 Al-Cu-Li alloy in an acidic environment was investigated by integrating microstructural characterization with 3D cellular automata (CA) simulation. Microstructural features, including the rolled grain morphology and the heterogeneous distribution of intermetallic compounds (IMs), were characterized using EBSD and TEM. An improved Voronoi-based approach was employed to reconstruct a rolled polycrystalline microstructure by incorporating EBSD-derived grain statistics. Immersion tests in 30 % HNO3 combined with quasi-in-situ SEM-FIB were conducted to reveal corrosion morphologies associated with IMs dissolution and preferential grain-boundary attack. Based on the corrosion mechanism of Al-Cu-Li alloys in acidic media, a microstructure-informed 3D CA model was developed by explicitly embedding the spatial distribution of IMs using six cell types and five transition rules. The model reproduces key processes including selective/partial IM dissolution, preferential grain-boundary dissolution, galvanic-driven matrix dissolution, and pit growth, and the simulated morphological evolution shows good qualitative and semi-quantitative agreement with experiments.
{"title":"Research on the evolution law of corrosion damage of 2195 Al-Cu-Li alloy in acidic environments and cellular automata simulation","authors":"Xinzhi Yang, Gan Tian, Dejun Liu, Hongsheng Liu, Hui Cai, Mengqing Liu, Biyun Ren","doi":"10.1016/j.ijpvp.2026.105755","DOIUrl":"10.1016/j.ijpvp.2026.105755","url":null,"abstract":"<div><div>In this study, the evolution of localized pitting and intergranular corrosion (IGC) of 2195-T8 Al-Cu-Li alloy in an acidic environment was investigated by integrating microstructural characterization with 3D cellular automata (CA) simulation. Microstructural features, including the rolled grain morphology and the heterogeneous distribution of intermetallic compounds (IMs), were characterized using EBSD and TEM. An improved Voronoi-based approach was employed to reconstruct a rolled polycrystalline microstructure by incorporating EBSD-derived grain statistics. Immersion tests in 30 % HNO<sub>3</sub> combined with quasi-in-situ SEM-FIB were conducted to reveal corrosion morphologies associated with IMs dissolution and preferential grain-boundary attack. Based on the corrosion mechanism of Al-Cu-Li alloys in acidic media, a microstructure-informed 3D CA model was developed by explicitly embedding the spatial distribution of IMs using six cell types and five transition rules. The model reproduces key processes including selective/partial IM dissolution, preferential grain-boundary dissolution, galvanic-driven matrix dissolution, and pit growth, and the simulated morphological evolution shows good qualitative and semi-quantitative agreement with experiments.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105755"},"PeriodicalIF":3.5,"publicationDate":"2026-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The last stage low pressure LP steam turbine blade operated for 3000 rpm was failed after 42000 equivalent hours of operation from 600 MW thermo electric plant. The fractured blade was investigated and compared with virgin blade to determine the failure mode. Visual examination, chemical analysis, uni-axial tensile, V-notch impact tests, bulk hardness, EDX, fractography and microstructural characterization were conducted on the fractured blade. Further, wet fluorescent magnetic particle inspection and surface roughness measurement conducted on virgin blade as well. Initial visual analysis suggested that chevron cracking accompanied with several ratchet marks. Moreover, dynamic analysis of last stage virgin blade was performed and evidenced that natural frequency was stable. Modal analysis had predicted using Finite Element Analysis. Both experimental and theoretical frequencies had been closely matched, and natural frequencies were well below the resonant frequency, thus, vibration had not induced fatigue fracture. Moreover, fractured blade was fractographic and metallographic analyzed for fatigue fracture characterization. An engineering failure analysis suggested that several non-metallic inclusions have been de-bonded at crack origin zone. Multiple source of fatigue cracks have been initiated adjacent to material anomalies and fatigue fracture propagated by alternating centrifugal induced tensile stress. Fine curved striations have been evidenced on fatigue crack initiation and propagation zones. The blade exhibited tempered martensite and tensile properties including hardness were within the specifications. The presence of anomalies including non-metallic inclusions and internal volumetric material defects has been linked with poor blade toughness which had reduced the fatigue resistance of last stage blade. Interaction of manganese sulfide inclusions with complex alternating centrifugal and bending stress had induced fatigue fracture. Several recommendations including blade manufacturing by clean steel technology are suggested based on various obtained evidences to prevent LPT blade failures in power plants.
{"title":"Fatigue fracture of last stage X20Cr13 low pressure turbine (LPT) blade from 600 MW thermal power station","authors":"Chidambaram Subramanian , Swarup Kr Laha , Sourav Kansabanik , Biplab Swarnakar , Debashis Ghosh","doi":"10.1016/j.ijpvp.2026.105751","DOIUrl":"10.1016/j.ijpvp.2026.105751","url":null,"abstract":"<div><div>The last stage low pressure LP steam turbine blade operated for 3000 rpm was failed after 42000 equivalent hours of operation from 600 MW thermo electric plant. The fractured blade was investigated and compared with virgin blade to determine the failure mode. Visual examination, chemical analysis, uni-axial tensile, V-notch impact tests, bulk hardness, EDX, fractography and microstructural characterization were conducted on the fractured blade. Further, wet fluorescent magnetic particle inspection and surface roughness measurement conducted on virgin blade as well. Initial visual analysis suggested that chevron cracking accompanied with several ratchet marks. Moreover, dynamic analysis of last stage virgin blade was performed and evidenced that natural frequency was stable. Modal analysis had predicted using Finite Element Analysis. Both experimental and theoretical frequencies had been closely matched, and natural frequencies were well below the resonant frequency, thus, vibration had not induced fatigue fracture. Moreover, fractured blade was fractographic and metallographic analyzed for fatigue fracture characterization. An engineering failure analysis suggested that several non-metallic inclusions have been de-bonded at crack origin zone. Multiple source of fatigue cracks have been initiated adjacent to material anomalies and fatigue fracture propagated by alternating centrifugal induced tensile stress. Fine curved striations have been evidenced on fatigue crack initiation and propagation zones. The blade exhibited tempered martensite and tensile properties including hardness were within the specifications. The presence of anomalies including non-metallic inclusions and internal volumetric material defects has been linked with poor blade toughness which had reduced the fatigue resistance of last stage blade. Interaction of manganese sulfide inclusions with complex alternating centrifugal and bending stress had induced fatigue fracture. Several recommendations including blade manufacturing by clean steel technology are suggested based on various obtained evidences to prevent LPT blade failures in power plants.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105751"},"PeriodicalIF":3.5,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145978880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-06DOI: 10.1016/j.ijpvp.2026.105753
T. Koers , B. Magyar , C. Bödger , T. Tröster
The state of the art shows that PBF-LB/M offers great potential for pressure-loaded parts, with significant weight reductions and simultaneous optimization of flow resistance. This study is aimed at applying existing calculation methods for pressure-loaded parts to additively manufactured pipe structures, considering the two materials EN AC-43000 (3.2381, AlSi10Mg) and AISI 316L (1.4404, X2CrNiMo17-12-2). For this purpose, systematic tensile tests are carried out for both materials. In addition, a statistical evaluation is performed to determine the design-relevant strength characteristics with a survival probability Ps of 97.5 % for both materials in the as-built and heat-treated condition.
Pipe specimens are manufactured, half of which are heat treated, geometrically measured and then subjected to a burst pressure test to experimentally determine the failure-critical internal pressure. These results are compared with calculated burst pressures. The calculations are based on the application-relevant methods identified in this study, considering the strength values determined for the respective material condition. This comparison is used to assess the suitability of the calculation methods for additively manufactured pipe structures, based on the materials investigated.
{"title":"Analytical and experimental determination of the failure-critical pressure of pipe structures manufactured by PBF-LB/M","authors":"T. Koers , B. Magyar , C. Bödger , T. Tröster","doi":"10.1016/j.ijpvp.2026.105753","DOIUrl":"10.1016/j.ijpvp.2026.105753","url":null,"abstract":"<div><div>The state of the art shows that PBF-LB/M offers great potential for pressure-loaded parts, with significant weight reductions and simultaneous optimization of flow resistance. This study is aimed at applying existing calculation methods for pressure-loaded parts to additively manufactured pipe structures, considering the two materials EN AC-43000 (3.2381, AlSi10Mg) and AISI 316L (1.4404, X2CrNiMo17-12-2). For this purpose, systematic tensile tests are carried out for both materials. In addition, a statistical evaluation is performed to determine the design-relevant strength characteristics with a survival probability <em>P</em><sub>s</sub> of 97.5 % for both materials in the as-built and heat-treated condition.</div><div>Pipe specimens are manufactured, half of which are heat treated, geometrically measured and then subjected to a burst pressure test to experimentally determine the failure-critical internal pressure. These results are compared with calculated burst pressures. The calculations are based on the application-relevant methods identified in this study, considering the strength values determined for the respective material condition. This comparison is used to assess the suitability of the calculation methods for additively manufactured pipe structures, based on the materials investigated.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105753"},"PeriodicalIF":3.5,"publicationDate":"2026-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.ijpvp.2025.105740
M.D. Mathew , J. Ganesh Kumar , K. Linga Murty
The ball indentation (BI) technique is a versatile and efficient small-scale testing method employed to assess the mechanical properties of metallic materials. In this method, a compressive force is gradually applied to a spherical indenter, which is pressed onto the material’s surface until a predetermined indentation depth is achieved. The indenter is then partially unloaded and reloaded. This loading-unloading cycle is repeated several times at incrementally increasing depths. Throughout the test, the indentation depth and the corresponding load are measured. This data is used to generate a load-depth curve. By combining semi-empirical relationships with elasticity and plasticity theories, this analysis yields the stress-strain curve that is characteristic of the material’s response to multiaxial indentation loading.
Key mechanical properties derived from the BI tests include hardness, flow curve, yield strength, ultimate tensile strength, and indentation energy to fracture. This testing method facilitates localized, point-to-point assessment of the mechanical properties of metallic materials. The technique is advantageous in evaluating narrow microstructural zones within weldments. The test method is minimally invasive as well. This makes ball indentation testing attractive for assessing the mechanical properties of structural components in service and for extending their life without compromising component integrity. The paper discusses a range of BI applications. Theoretical models, AI-assisted data analysis, portable in-situ BI system, and other critical issues, as well as future scenarios, are also discussed.
{"title":"Ball indentation test: A versatile small-scale testing method for evaluating mechanical properties of materials","authors":"M.D. Mathew , J. Ganesh Kumar , K. Linga Murty","doi":"10.1016/j.ijpvp.2025.105740","DOIUrl":"10.1016/j.ijpvp.2025.105740","url":null,"abstract":"<div><div>The ball indentation (BI) technique is a versatile and efficient small-scale testing method employed to assess the mechanical properties of metallic materials. In this method, a compressive force is gradually applied to a spherical indenter, which is pressed onto the material’s surface until a predetermined indentation depth is achieved. The indenter is then partially unloaded and reloaded. This loading-unloading cycle is repeated several times at incrementally increasing depths. Throughout the test, the indentation depth and the corresponding load are measured. This data is used to generate a load-depth curve. By combining semi-empirical relationships with elasticity and plasticity theories, this analysis yields the stress-strain curve that is characteristic of the material’s response to multiaxial indentation loading.</div><div>Key mechanical properties derived from the BI tests include hardness, flow curve, yield strength, ultimate tensile strength, and indentation energy to fracture. This testing method facilitates localized, point-to-point assessment of the mechanical properties of metallic materials. The technique is advantageous in evaluating narrow microstructural zones within weldments. The test method is minimally invasive as well. This makes ball indentation testing attractive for assessing the mechanical properties of structural components in service and for extending their life without compromising component integrity. The paper discusses a range of BI applications. Theoretical models, AI-assisted data analysis, portable in-situ BI system, and other critical issues, as well as future scenarios, are also discussed.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105740"},"PeriodicalIF":3.5,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-03DOI: 10.1016/j.ijpvp.2025.105741
Lei Chen , Wenjing Yang , Jianping Zhou , Zhenxi Liu , Zhanshu Lv , Yanwei Hu , Jian Li , Xingqing Yan , Jianliang Yu , Shaoyun Chen
To address the safety risks associated with pipeline fractures in carbon capture, utilization, and storage (CCUS) systems, this study constructed a full-scale experimental platform for supercritical CO2 pipelines containing impurities and conducted systematic fracture tests under three sets of conditions with varying initial pressures (9.8–11.6 MPa) and N2 molar concentrations (2 %–4 %). A self-developed data acquisition system, integrated with high-frequency pressure transducers, T-type armored thermocouples, and a high-speed camera (capturing crack propagation processes), was employed to monitor the dynamic evolutions of pressure, temperature, decompression wave propagation, and crack tip behavior during pipeline fracture. The results indicated that pipeline fracture induced four distinct pressure change stages: rapid decline (Stage Ⅰ), pressure oscillation (Stage Ⅱ), negative exponential decline (Stage Ⅲ), and static leakage (Stage Ⅳ). Axially, the internal temperature decreased first near the fracture and later at locations farther from it; vertically, the minimum temperature at all measuring points predominantly occurred at the pipeline bottom. The decompression wave velocity exhibited a linear decrease in Stage Ⅰ, formed a “pressure plateau” in Stage Ⅱ, and decreased irregularly in Stages Ⅲ–Ⅳ due to subcooled and superheated states caused by pressure instability. Higher initial pressure and N2 molar concentration both contributed to an increase in the initial decompression wave velocity and the “pressure plateau” value. Additionally, the self-designed fracture recording system successfully captured the complete process of pipeline failure, crack initiation, ductile propagation, and arrest. The crack tip opening angle (CTOA) fluctuated within 14.3°–21.2° along the propagation path and showed a gradual decreasing trend, while the crack propagation velocity first increased, maintained a stable phase, and then decreased. Notably, a higher N2 molar concentration led to a higher stable fracture velocity. This research provides critical experimental data and theoretical support for the safety design and fracture control of supercritical CO2 pipelines in CCUS projects.
{"title":"Experimental investigation on full-scale fracture behavior and dynamic response of supercritical CO2 pipelines with N2 impurities","authors":"Lei Chen , Wenjing Yang , Jianping Zhou , Zhenxi Liu , Zhanshu Lv , Yanwei Hu , Jian Li , Xingqing Yan , Jianliang Yu , Shaoyun Chen","doi":"10.1016/j.ijpvp.2025.105741","DOIUrl":"10.1016/j.ijpvp.2025.105741","url":null,"abstract":"<div><div>To address the safety risks associated with pipeline fractures in carbon capture, utilization, and storage (CCUS) systems, this study constructed a full-scale experimental platform for supercritical CO<sub>2</sub> pipelines containing impurities and conducted systematic fracture tests under three sets of conditions with varying initial pressures (9.8–11.6 MPa) and N<sub>2</sub> molar concentrations (2 %–4 %). A self-developed data acquisition system, integrated with high-frequency pressure transducers, T-type armored thermocouples, and a high-speed camera (capturing crack propagation processes), was employed to monitor the dynamic evolutions of pressure, temperature, decompression wave propagation, and crack tip behavior during pipeline fracture. The results indicated that pipeline fracture induced four distinct pressure change stages: rapid decline (Stage Ⅰ), pressure oscillation (Stage Ⅱ), negative exponential decline (Stage Ⅲ), and static leakage (Stage Ⅳ). Axially, the internal temperature decreased first near the fracture and later at locations farther from it; vertically, the minimum temperature at all measuring points predominantly occurred at the pipeline bottom. The decompression wave velocity exhibited a linear decrease in Stage Ⅰ, formed a “pressure plateau” in Stage Ⅱ, and decreased irregularly in Stages Ⅲ–Ⅳ due to subcooled and superheated states caused by pressure instability. Higher initial pressure and N<sub>2</sub> molar concentration both contributed to an increase in the initial decompression wave velocity and the “pressure plateau” value. Additionally, the self-designed fracture recording system successfully captured the complete process of pipeline failure, crack initiation, ductile propagation, and arrest. The crack tip opening angle (<em>CTOA</em>) fluctuated within 14.3°–21.2° along the propagation path and showed a gradual decreasing trend, while the crack propagation velocity first increased, maintained a stable phase, and then decreased. Notably, a higher N<sub>2</sub> molar concentration led to a higher stable fracture velocity. This research provides critical experimental data and theoretical support for the safety design and fracture control of supercritical CO<sub>2</sub> pipelines in CCUS projects.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105741"},"PeriodicalIF":3.5,"publicationDate":"2026-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-31DOI: 10.1016/j.ijpvp.2025.105744
Kai Liu, WeiWei Liu, ShaoWei Wu, BoQun Xie, Xin Liu
The reactor pressure vessels (RPVs) are key components in nuclear power plants, and their structural integrity assessment is of great significance for the safe and stable operation of nuclear power plants. To address issues such as low computational efficiency and limited applicability of existing assessment methods, this study proposes an innovative collaborative prediction method based on the extended finite element method (XFEM) and the particle swarm optimization neural network (PSONN). This method enables rapid and accurate prediction of stress intensity factors (SIFs) under the combined influence of multiple parameters including crack geometric parameters, container structure dimensions and internal pressure. Firstly, a parametric model including typical crack configurations such as beltline shells and nozzle corners is established using XFEM, and a comprehensive database of SIFs is constructed. By systematically comparing the predictive performance of eight machine learning (ML) algorithms, a neural network model based on Particle Swarm Optimization is developed. And K-fold cross-validation and grid search techniques are adopted to optimize the model's hyperparameters. The interpretability analysis of SHAP indicates that internal pressure and crack inclination Angle are the most critical parameters affecting the prediction accuracy. By effectively integrating the physical accuracy of XFEM with the computational efficiency of PSONN, the proposed method provides a practical tool for rapid and accurate safety assessment upon crack detection in in-service inspections.
{"title":"Intelligent prediction of crack stress intensity factors for nuclear-grade pressure vessels based on XFEM-PSONN collaboration","authors":"Kai Liu, WeiWei Liu, ShaoWei Wu, BoQun Xie, Xin Liu","doi":"10.1016/j.ijpvp.2025.105744","DOIUrl":"10.1016/j.ijpvp.2025.105744","url":null,"abstract":"<div><div>The reactor pressure vessels (RPVs) are key components in nuclear power plants, and their structural integrity assessment is of great significance for the safe and stable operation of nuclear power plants. To address issues such as low computational efficiency and limited applicability of existing assessment methods, this study proposes an innovative collaborative prediction method based on the extended finite element method (XFEM) and the particle swarm optimization neural network (PSONN). This method enables rapid and accurate prediction of stress intensity factors (SIFs) under the combined influence of multiple parameters including crack geometric parameters, container structure dimensions and internal pressure. Firstly, a parametric model including typical crack configurations such as beltline shells and nozzle corners is established using XFEM, and a comprehensive database of SIFs is constructed. By systematically comparing the predictive performance of eight machine learning (ML) algorithms, a neural network model based on Particle Swarm Optimization is developed. And K-fold cross-validation and grid search techniques are adopted to optimize the model's hyperparameters. The interpretability analysis of SHAP indicates that internal pressure and crack inclination Angle are the most critical parameters affecting the prediction accuracy. By effectively integrating the physical accuracy of XFEM with the computational efficiency of PSONN, the proposed method provides a practical tool for rapid and accurate safety assessment upon crack detection in in-service inspections.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105744"},"PeriodicalIF":3.5,"publicationDate":"2025-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145877098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-30DOI: 10.1016/j.ijpvp.2025.105742
Ruiyuan Xue , Xuezong Zhang , Juyin Zhang , Xueping Wang , Yongnan Zhang , Linbin Li , Yongzhi Luo
A digital twin-driven online stress prediction method is proposed to address the stress monitoring requirements for multi-layer wrapped high-pressure hydrogen storage vessels. This method establishes a phased computational framework (offline/online): During the offline phase, the global stress field is computed using the Finite Element Method (FEM), and a random forest hybrid regression prediction model incorporating the whale optimization algorithm (WOA-RF) is trained to establish the mapping relationship between container load, structural features, node coordinates, and stress. During the online phase, the deviation between measured local stresses and offline-predicted stresses is first calculated. Subsequently, a K-Nearest Neighbors (KNN) algorithm constructs a surrogate model linking load-node coordinates to stress deviation. Ultimately, the KNN model is driven by locally acquired real-time measurement data, utilizing its output stress deviation to perform real-time corrections on WOA-RF prediction results, thereby achieving global twin stress prediction for the monitored vessel. To establish a more accurate finite element model during the offline phase, this paper innovatively derives a method for inverting interlayer preload in multilayer vessels based on measured data. Verification conducted on a multi-layer wrapped high-pressure reactor demonstrated that the proposed stress monitoring method achieved prediction errors ranging from 0.4 % to 10 %. Furthermore, the findings elucidate the random and non-uniform stress distribution characteristics exhibited by multi-layer wrapped vessels under loading, which stem from the complex interlayer preload generated during the manufacturing process.
{"title":"Stress distribution characteristics and intelligent online monitoring methods for multilayer wound pressure vessel","authors":"Ruiyuan Xue , Xuezong Zhang , Juyin Zhang , Xueping Wang , Yongnan Zhang , Linbin Li , Yongzhi Luo","doi":"10.1016/j.ijpvp.2025.105742","DOIUrl":"10.1016/j.ijpvp.2025.105742","url":null,"abstract":"<div><div>A digital twin-driven online stress prediction method is proposed to address the stress monitoring requirements for multi-layer wrapped high-pressure hydrogen storage vessels. This method establishes a phased computational framework (offline/online): During the offline phase, the global stress field is computed using the Finite Element Method (FEM), and a random forest hybrid regression prediction model incorporating the whale optimization algorithm (WOA-RF) is trained to establish the mapping relationship between container load, structural features, node coordinates, and stress. During the online phase, the deviation between measured local stresses and offline-predicted stresses is first calculated. Subsequently, a K-Nearest Neighbors (KNN) algorithm constructs a surrogate model linking load-node coordinates to stress deviation. Ultimately, the KNN model is driven by locally acquired real-time measurement data, utilizing its output stress deviation to perform real-time corrections on WOA-RF prediction results, thereby achieving global twin stress prediction for the monitored vessel. To establish a more accurate finite element model during the offline phase, this paper innovatively derives a method for inverting interlayer preload in multilayer vessels based on measured data. Verification conducted on a multi-layer wrapped high-pressure reactor demonstrated that the proposed stress monitoring method achieved prediction errors ranging from 0.4 % to 10 %. Furthermore, the findings elucidate the random and non-uniform stress distribution characteristics exhibited by multi-layer wrapped vessels under loading, which stem from the complex interlayer preload generated during the manufacturing process.</div></div>","PeriodicalId":54946,"journal":{"name":"International Journal of Pressure Vessels and Piping","volume":"221 ","pages":"Article 105742"},"PeriodicalIF":3.5,"publicationDate":"2025-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145928126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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