Cracking of steels in refinery H2S service occurs in two regimes: 1) low pH and 2) high pH. Cracking in the low pH regime (pH < 6 or 7) is associated with ingress of hydrogen from metal dissolution with H2S poisoning the hydrogen recombination reaction. In the high pH regime (pH > 7), cracking requires the presence of species other than just H2S. While this has been a subject of interest since the failure of an amine absorber tower in 1984, limited laboratory testing has been conducted in either regime. The majority of test data that does exist was from studies conducted in more aggressive environments, such as NACE A or NACE B solutions. Additionally, most of the work was conducted on more modern steels rather than service aged of vintage steel. The lack of available data inhibits the ability to perform fitness for service (FFS) assessments without using overly conservative approaches. A recent test program was undertaken to evaluate the fracture toughness properties of the weld heat-affected zone (HAZ) of an ex-service steel in mildly acidic sour water environments more typical of the downstream refining industry. The results of the test program, including the test environment and approach are discussed. In addition to the test program, the current state of understanding sour water cracking is reviewed relative to both the low pH and high pH regimes. The gaps in the current knowledge are discussed.
{"title":"Fracture Toughness Behavior of Welded Service Aged Carbon Steels in Mildly Sour Waters","authors":"B. C. Rollins, J. Penso","doi":"10.1115/pvp2022-85807","DOIUrl":"https://doi.org/10.1115/pvp2022-85807","url":null,"abstract":"\u0000 Cracking of steels in refinery H2S service occurs in two regimes: 1) low pH and 2) high pH. Cracking in the low pH regime (pH < 6 or 7) is associated with ingress of hydrogen from metal dissolution with H2S poisoning the hydrogen recombination reaction. In the high pH regime (pH > 7), cracking requires the presence of species other than just H2S. While this has been a subject of interest since the failure of an amine absorber tower in 1984, limited laboratory testing has been conducted in either regime. The majority of test data that does exist was from studies conducted in more aggressive environments, such as NACE A or NACE B solutions. Additionally, most of the work was conducted on more modern steels rather than service aged of vintage steel. The lack of available data inhibits the ability to perform fitness for service (FFS) assessments without using overly conservative approaches.\u0000 A recent test program was undertaken to evaluate the fracture toughness properties of the weld heat-affected zone (HAZ) of an ex-service steel in mildly acidic sour water environments more typical of the downstream refining industry. The results of the test program, including the test environment and approach are discussed. In addition to the test program, the current state of understanding sour water cracking is reviewed relative to both the low pH and high pH regimes. The gaps in the current knowledge are discussed.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124969813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Lindqvist, N. Hytönen, L. Sirkiä, P. Arffman, J. Lydman, Yanling Ge, P. Nevasmaa, Z. Que
The fracture toughness in the ductile-to-brittle transition region is determined for the heat-affected zone (HAZ) adjacent to the fusion boundary between a low alloy steel (LAS) and the weld metal of narrow-gap Alloy 52 dissimilar metal weld (DMW) after 15 000 h of thermal aging at 400 °C and of an Alloy 52 DMW with buttering in reference condition. The fracture toughness testing is done according to ASTM E1921, and fractography and cross-section metallography are applied to characterize the crack paths, crack locations and fracture type. The T0 transition temperature for the DMW with buttering is −117 °C, indicating marginally higher toughness compared to the narrow-gap DMW. The cracks close to the fusion boundary (approximately 200 μm) in both DMWs deviate from the HAZ towards the fusion boundary. The thermal aging treatment of the narrow-gap Alloy 52 DMW does not significantly affect the fracture toughness properties of the fusion boundary. Further research is needed to better understand the lower boundary fracture toughness behavior at approximately 300 μm from the fusion boundary. The results contribute to long-term operation assessment of nuclear power plants, and development of analysis and characterization methods for DMWs related to the effect of crack path and location.
{"title":"Fracture in the Ductile-To-Brittle Transition Region of A Narrow-Gap Alloy 52 and Alloy 52 Dissimilar Metal Weld With Buttering","authors":"S. Lindqvist, N. Hytönen, L. Sirkiä, P. Arffman, J. Lydman, Yanling Ge, P. Nevasmaa, Z. Que","doi":"10.1115/pvp2022-80690","DOIUrl":"https://doi.org/10.1115/pvp2022-80690","url":null,"abstract":"\u0000 The fracture toughness in the ductile-to-brittle transition region is determined for the heat-affected zone (HAZ) adjacent to the fusion boundary between a low alloy steel (LAS) and the weld metal of narrow-gap Alloy 52 dissimilar metal weld (DMW) after 15 000 h of thermal aging at 400 °C and of an Alloy 52 DMW with buttering in reference condition. The fracture toughness testing is done according to ASTM E1921, and fractography and cross-section metallography are applied to characterize the crack paths, crack locations and fracture type. The T0 transition temperature for the DMW with buttering is −117 °C, indicating marginally higher toughness compared to the narrow-gap DMW. The cracks close to the fusion boundary (approximately 200 μm) in both DMWs deviate from the HAZ towards the fusion boundary. The thermal aging treatment of the narrow-gap Alloy 52 DMW does not significantly affect the fracture toughness properties of the fusion boundary. Further research is needed to better understand the lower boundary fracture toughness behavior at approximately 300 μm from the fusion boundary. The results contribute to long-term operation assessment of nuclear power plants, and development of analysis and characterization methods for DMWs related to the effect of crack path and location.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126701758","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Glenn Trownson, Peter Gill, W. Brayshaw, J. Watson, J. Mann
The effect of a Pressurised Water Reactor (PWR) environment on fatigue life is currently assessed using methods such as NUREG/CR-6909 for initiation and ASME Code Case N809 for crack growth, which may be inherently conservative for certain components, especially when considering plant relevant loading. The thermal shock testing with thick-walled specimens as discussed in this paper allows for more plant relevant loading regimes to be utilised in assessments, incorporating through-wall stress gradients, thick walled test specimens and out-of-phase temperature/strain characteristics. This should lead to improvements in reducing the levels of excess conservatism in current assessment methodologies. The capability of the test facility was first presented in PVP2016-63161 [4]. Since then, significant modifications have been made in order to maximise the achievable strain amplitudes in the thick-walled specimen geometry, alongside minimising typical test durations. This was achieved by maximising the temperature differential between the hot and cold cycles and tuning the cycle length in order to ensure that the cycle is long enough to achieve a target strain amplitude, whilst ensuring that it is not so long as to unreasonably increase test durations. This paper details the results of the thermal shock testing performed to date, the development of accompanying Finite Element Analysis (FEA), preliminary initiation data and the development of the various Non Destructive Testing (NDT) techniques used to detect fatigue crack initiation on the thick-walled specimens. Owing to the long testing times needed to achieve the required cycling, various NDT techniques were developed and employed to confirm the presence of fatigue cracking in the thick-walled test specimens before considering more in-depth characterisation using destructive techniques. Eddy Current Array (ECA) testing has been specifically developed for this testing and uses a 360-degree custom bore probe to conduct non-contact ECA measurements on the inner surface of the test specimens. Calibration blocks containing various sized Electrical Discharge Machining (EDM) notches were used to provide a calibration (amplitude and phase) of eddy current responses for prospective flaw depth sizing from indications. The ECA testing performed has provided indications that fatigue cracking is present within the thick-walled specimens tested and subsequent Visual Testing (VT) was performed to assess the highlighted indications from the ECA testing. The VT methods employed included a video borescope for imaging the inner walls of the specimen. In order to increase the detection capabilities (by improving the contrast) the VT was used in conjunction with fluorescent Dye-Penetrant (fDP) testing, whereby a method was developed for using fDP within the inside bore of the specimen alongside a custom ultraviolet (UV) source to better highlight cracking. This paper discusses the success of the NDT developments and
{"title":"Thermomechanical Fatigue Initiation in Nuclear Grades of Austenitic Stainless Steel Using Plant Realistic Loading","authors":"Glenn Trownson, Peter Gill, W. Brayshaw, J. Watson, J. Mann","doi":"10.1115/pvp2022-84760","DOIUrl":"https://doi.org/10.1115/pvp2022-84760","url":null,"abstract":"\u0000 The effect of a Pressurised Water Reactor (PWR) environment on fatigue life is currently assessed using methods such as NUREG/CR-6909 for initiation and ASME Code Case N809 for crack growth, which may be inherently conservative for certain components, especially when considering plant relevant loading. The thermal shock testing with thick-walled specimens as discussed in this paper allows for more plant relevant loading regimes to be utilised in assessments, incorporating through-wall stress gradients, thick walled test specimens and out-of-phase temperature/strain characteristics. This should lead to improvements in reducing the levels of excess conservatism in current assessment methodologies.\u0000 The capability of the test facility was first presented in PVP2016-63161 [4]. Since then, significant modifications have been made in order to maximise the achievable strain amplitudes in the thick-walled specimen geometry, alongside minimising typical test durations. This was achieved by maximising the temperature differential between the hot and cold cycles and tuning the cycle length in order to ensure that the cycle is long enough to achieve a target strain amplitude, whilst ensuring that it is not so long as to unreasonably increase test durations.\u0000 This paper details the results of the thermal shock testing performed to date, the development of accompanying Finite Element Analysis (FEA), preliminary initiation data and the development of the various Non Destructive Testing (NDT) techniques used to detect fatigue crack initiation on the thick-walled specimens. Owing to the long testing times needed to achieve the required cycling, various NDT techniques were developed and employed to confirm the presence of fatigue cracking in the thick-walled test specimens before considering more in-depth characterisation using destructive techniques.\u0000 Eddy Current Array (ECA) testing has been specifically developed for this testing and uses a 360-degree custom bore probe to conduct non-contact ECA measurements on the inner surface of the test specimens. Calibration blocks containing various sized Electrical Discharge Machining (EDM) notches were used to provide a calibration (amplitude and phase) of eddy current responses for prospective flaw depth sizing from indications. The ECA testing performed has provided indications that fatigue cracking is present within the thick-walled specimens tested and subsequent Visual Testing (VT) was performed to assess the highlighted indications from the ECA testing. The VT methods employed included a video borescope for imaging the inner walls of the specimen. In order to increase the detection capabilities (by improving the contrast) the VT was used in conjunction with fluorescent Dye-Penetrant (fDP) testing, whereby a method was developed for using fDP within the inside bore of the specimen alongside a custom ultraviolet (UV) source to better highlight cracking.\u0000 This paper discusses the success of the NDT developments and","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129170686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Shigeyama, Yukio Takahashi, K. Tamura, M. Yaguchi, S. Nishinoiri
Type IV creep damage has been frequently reported in longitudinal welds and nozzle welds. Many studies have been conducted on the longitudinal welds, and the applicability of life evaluation by non-destructive testing and numerical analysis has been examined. On the other hand, there are few studies on the nozzle welds, and the applicability of the existing life evaluation method is not clear. In this study, internal pressure creep test and numerical analysis were carried out on a large diameter pipe specimen which has several welded nozzles in order to clarify the applicability of the creep life evaluation method for the nozzle welds. This first report describes the experimental part. The internal pressure creep test at 650°C was performed on the large-diameter pipe specimen of modified 9Cr-1Mo (ASME P91) steel. The test was interrupted three times and nondestructive inspections were performed at each interruption. They included phased array ultrasonic testing, magnetic particle testing and replica observation. The test was completed when the test time reached about 20,000 hours and cross-sectional observations were performed after the specimen was cut into many pieces. Based on these efforts, the location and process of creep damage development in the nozzle welds and the effectiveness of non-destructive inspection were revealed.
{"title":"Development of Life Estimation Method for Nozzle Welds in Large Scale Piping of Modified 9Cr-1Mo Steel -Part I: Experimental Study","authors":"H. Shigeyama, Yukio Takahashi, K. Tamura, M. Yaguchi, S. Nishinoiri","doi":"10.1115/pvp2022-84220","DOIUrl":"https://doi.org/10.1115/pvp2022-84220","url":null,"abstract":"\u0000 Type IV creep damage has been frequently reported in longitudinal welds and nozzle welds. Many studies have been conducted on the longitudinal welds, and the applicability of life evaluation by non-destructive testing and numerical analysis has been examined. On the other hand, there are few studies on the nozzle welds, and the applicability of the existing life evaluation method is not clear. In this study, internal pressure creep test and numerical analysis were carried out on a large diameter pipe specimen which has several welded nozzles in order to clarify the applicability of the creep life evaluation method for the nozzle welds.\u0000 This first report describes the experimental part. The internal pressure creep test at 650°C was performed on the large-diameter pipe specimen of modified 9Cr-1Mo (ASME P91) steel. The test was interrupted three times and nondestructive inspections were performed at each interruption. They included phased array ultrasonic testing, magnetic particle testing and replica observation. The test was completed when the test time reached about 20,000 hours and cross-sectional observations were performed after the specimen was cut into many pieces. Based on these efforts, the location and process of creep damage development in the nozzle welds and the effectiveness of non-destructive inspection were revealed.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116261442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compact heat exchangers are of interest for a number of applications including advanced reactors. Alloy 617 is one of the top candidate materials for the gas-cooled reactor intermediate heat exchanger. Previous endeavors to diffusion weld Alloy 617 utilized hot pressing (HP). It was reported that grain boundary migration across the interface was hindered by extensive precipitation. Bonds of this nature have been observed to reduce the elevated-temperature mechanical properties compared to the wrought-product form. It was hypothesized that the electric current applied during electric-field-assisted sintering (EFAS) can overcome these challenges, resulting in improved diffusion welding (DW). This study investigated DW of Alloy 617 via EFAS. Stacks composed of three sheets that were 20 mm in diameter were welded using EFAS. Specimens were welded with an applied electric current, a pressure of 30 MPa, hold time of 30 min, and temperatures of 1050°C, 1100°C, and 1150°C. DW using HP as the zero-current analog of EFAS was also performed at the most promising EFAS conditions. Results revealed that both the applied electric current and temperature played a key role in precipitation and grain boundary migration in diffusion-welded Alloy 617. Precipitates were observed at the interface of the hot-pressed samples which limited grain boundary migration. Electric current was found to prevent precipitate formation along the interface at 1150°C. The electric current coupled with a temperature of 1150°C during EFAS resulted in significant grain boundary migration across the interface.
{"title":"Electric-Field-Assisted Diffusion Welding to Fabricate Alloy 617 Compact Heat Exchangers","authors":"Xinchang Zhang, R. Rupp, J. Rufner, M. McMurtrey","doi":"10.1115/pvp2022-83842","DOIUrl":"https://doi.org/10.1115/pvp2022-83842","url":null,"abstract":"\u0000 Compact heat exchangers are of interest for a number of applications including advanced reactors. Alloy 617 is one of the top candidate materials for the gas-cooled reactor intermediate heat exchanger. Previous endeavors to diffusion weld Alloy 617 utilized hot pressing (HP). It was reported that grain boundary migration across the interface was hindered by extensive precipitation. Bonds of this nature have been observed to reduce the elevated-temperature mechanical properties compared to the wrought-product form. It was hypothesized that the electric current applied during electric-field-assisted sintering (EFAS) can overcome these challenges, resulting in improved diffusion welding (DW). This study investigated DW of Alloy 617 via EFAS. Stacks composed of three sheets that were 20 mm in diameter were welded using EFAS. Specimens were welded with an applied electric current, a pressure of 30 MPa, hold time of 30 min, and temperatures of 1050°C, 1100°C, and 1150°C. DW using HP as the zero-current analog of EFAS was also performed at the most promising EFAS conditions. Results revealed that both the applied electric current and temperature played a key role in precipitation and grain boundary migration in diffusion-welded Alloy 617. Precipitates were observed at the interface of the hot-pressed samples which limited grain boundary migration. Electric current was found to prevent precipitate formation along the interface at 1150°C. The electric current coupled with a temperature of 1150°C during EFAS resulted in significant grain boundary migration across the interface.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127958760","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cellular structures are a class of materials that offer greater stiffness, strength-to-weight ratio, good energy absorption capacity, and high heat transfer capability compared to solid parts. Metallic lattice structures have been applied in different industry sectors, such as in biomedical implants, lightweight components, energy absorbers, and catalytic reactors. With the development of advanced manufacturing techniques, especially additive manufacturing (AM), lattice structures with complicated designs can be produced. Lattice structure-based heat exchangers produced by AM techniques have recently gained significant attention due to their promising performance. Interconnected cavities in lattice structures provide flow of fluid and effective thermal conductivity, which is desirable in heat exchangers. AM methods provide the possibility to promote tortuosity and intricate flow patterns leading to improved performance of heat exchangers. Between different AM techniques, laser powder bed fusion (LPBF) proved to be a suitable method for the manufacture of heat exchangers. Using LPBF methods, the distribution and geometry of cavities in the structure can be controlled with an accuracy that is typically better than for other AM methods. Although LPBF-produced heat exchanger showed enhanced thermal conductance, there are limitations associated with LPBF fabrication, such as surface roughness and need for post processing. In order to bridge this gap, the effects of different process parameters and levels of structural complexity in LPBF processes need to be evaluated. In this context, the present contribution constitutes a position paper that contrasts the opportunities that LPBF may provide for the fabrication of heat exchangers with the challenges that need to be overcome to realize design solutions that meet industry demands.
{"title":"Complex Lattice Structure-Based Heat Exchangers Through Additive Manufacturing: Opportunities and Challenges","authors":"Jerome Wong, A. Qureshi, P. Mertiny","doi":"10.1115/pvp2022-84355","DOIUrl":"https://doi.org/10.1115/pvp2022-84355","url":null,"abstract":"\u0000 Cellular structures are a class of materials that offer greater stiffness, strength-to-weight ratio, good energy absorption capacity, and high heat transfer capability compared to solid parts. Metallic lattice structures have been applied in different industry sectors, such as in biomedical implants, lightweight components, energy absorbers, and catalytic reactors. With the development of advanced manufacturing techniques, especially additive manufacturing (AM), lattice structures with complicated designs can be produced. Lattice structure-based heat exchangers produced by AM techniques have recently gained significant attention due to their promising performance. Interconnected cavities in lattice structures provide flow of fluid and effective thermal conductivity, which is desirable in heat exchangers. AM methods provide the possibility to promote tortuosity and intricate flow patterns leading to improved performance of heat exchangers. Between different AM techniques, laser powder bed fusion (LPBF) proved to be a suitable method for the manufacture of heat exchangers. Using LPBF methods, the distribution and geometry of cavities in the structure can be controlled with an accuracy that is typically better than for other AM methods. Although LPBF-produced heat exchanger showed enhanced thermal conductance, there are limitations associated with LPBF fabrication, such as surface roughness and need for post processing. In order to bridge this gap, the effects of different process parameters and levels of structural complexity in LPBF processes need to be evaluated. In this context, the present contribution constitutes a position paper that contrasts the opportunities that LPBF may provide for the fabrication of heat exchangers with the challenges that need to be overcome to realize design solutions that meet industry demands.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130128597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in the power plants with high priority. Its management has been conducted with conservative evaluation of thinning rate, and residual lifetime of piping based on wall thickness measurements. However, noticeable case of the wall thinning occurred in branch and junction piping (T-tube). There is a problem to manage the wall thickness beneath reinforcing plate of the T-tube, because measurement of this area is difficult to be conducted with ordinary ultrasonic testing devices due to the presence of the reinforcing plate. In this study, numerical analysis for the T-tube was conducted, and the wall thinning profile due to the FAC was evaluated by calculating the mass transfer coefficient. It was found that when the flows from the branch pipe and the main pipe merge or diverge, a localized wall thinning distribution occurs in the area where the reinforcement plate of the T-tube exists, and this tendency is affected by Reynolds number. It was suggested that the maximum amount of wall thinning in T-tube can be predicted by the flow rate ratio and the diameter ratio. In the future, we will confirm the effectiveness of the proposed decay function by comparing it with measurements taken in actual plants, and apply it to the management of wall thinning in actual plants.
{"title":"Development of Predictive Evaluation Methods of Pipe Wall Thinning by Flow Accelerated Corrosion at Drift Region in Junction Piping","authors":"Shun Watanabe, R. Morita","doi":"10.1115/pvp2022-84566","DOIUrl":"https://doi.org/10.1115/pvp2022-84566","url":null,"abstract":"\u0000 Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in the power plants with high priority. Its management has been conducted with conservative evaluation of thinning rate, and residual lifetime of piping based on wall thickness measurements. However, noticeable case of the wall thinning occurred in branch and junction piping (T-tube). There is a problem to manage the wall thickness beneath reinforcing plate of the T-tube, because measurement of this area is difficult to be conducted with ordinary ultrasonic testing devices due to the presence of the reinforcing plate. In this study, numerical analysis for the T-tube was conducted, and the wall thinning profile due to the FAC was evaluated by calculating the mass transfer coefficient. It was found that when the flows from the branch pipe and the main pipe merge or diverge, a localized wall thinning distribution occurs in the area where the reinforcement plate of the T-tube exists, and this tendency is affected by Reynolds number. It was suggested that the maximum amount of wall thinning in T-tube can be predicted by the flow rate ratio and the diameter ratio. In the future, we will confirm the effectiveness of the proposed decay function by comparing it with measurements taken in actual plants, and apply it to the management of wall thinning in actual plants.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133600973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fatigue crack growth calculation method beyond ΔK in codes and standards, like ASME Sec. XI or JSME rules for Fitness for Service has not been established even in Mode I. In the FDF-II Subcommittee of the nuclear research committee of the Japan Welding Engineering Society, an evaluation procedure for fatigue crack growth beyond small scale yielding using ΔJ has been investigated for several years. Since the evaluation procedure in the Subcommittee is to be incorporated into codes and standards, it should not be complex. Therefore the reference stress approach was tried to apply to calculate J-integral as a simplified procedure. Several formulae for J-integral calculation based on the reference stress approach were proposed by researchers. The authors joined the Subcommittee and performed finite element analyses for a sample problem to confirm the accuracy of those formulae, which were for a pipe with a circumferential part-through wall flaw subjected by bending load. The reference stress-based J, whose accuracy was confirmed by the authors, was applied to predict crack growth behaviors of pipes with a circumferential surface flaw under cyclic bending load conducted by other researches a decade ago. The difference of the failure cycles between the prediction and the experiment were nearly within a factor of 2. Since the verification of the simplified procedure was performed for just one case, more verification cases were needed to incorporate the procedure into codes and standards.
{"title":"Fatigue Crack Growth Prediction of a Pipe With a Circumferential Surface Flaw Using ΔJ and Reference Stress Method","authors":"Kiminobu Hojo, S. Kumagai","doi":"10.1115/pvp2022-84555","DOIUrl":"https://doi.org/10.1115/pvp2022-84555","url":null,"abstract":"\u0000 Fatigue crack growth calculation method beyond ΔK in codes and standards, like ASME Sec. XI or JSME rules for Fitness for Service has not been established even in Mode I. In the FDF-II Subcommittee of the nuclear research committee of the Japan Welding Engineering Society, an evaluation procedure for fatigue crack growth beyond small scale yielding using ΔJ has been investigated for several years. Since the evaluation procedure in the Subcommittee is to be incorporated into codes and standards, it should not be complex. Therefore the reference stress approach was tried to apply to calculate J-integral as a simplified procedure. Several formulae for J-integral calculation based on the reference stress approach were proposed by researchers. The authors joined the Subcommittee and performed finite element analyses for a sample problem to confirm the accuracy of those formulae, which were for a pipe with a circumferential part-through wall flaw subjected by bending load. The reference stress-based J, whose accuracy was confirmed by the authors, was applied to predict crack growth behaviors of pipes with a circumferential surface flaw under cyclic bending load conducted by other researches a decade ago. The difference of the failure cycles between the prediction and the experiment were nearly within a factor of 2. Since the verification of the simplified procedure was performed for just one case, more verification cases were needed to incorporate the procedure into codes and standards.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131386425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, the durability of the E-glass/epoxy was investigated in terms of degradation in tensile properties and microstructure. Specimens were conditioned in seawater under sustained load and without load at 23 °C, 45 °C and 65 °C for the period of 15 months. The tensile strength of the E-glass/epoxy reduced gradually with immersion time. It reduced by 11% from 811 MPa to 721 MPa and by 18.2% from 811 MPa to 663 MPa for samples immersed without load and with 15% sustained load respectively. The respective reduction for 23°C and 45°C was 1.1% and 5.5% for samples without load and 6.2% and 11.3% for samples immersion under 15% sustained load after 15 months of exposure. The failure strain of E-glass/epoxy composite was slightly affected for the samples immersed without load during the period of 15 months but it was more noticeable under 15% sustained load at 65°C when the tensile strain reduced to 1.65% after 15 months of immersion. Furthermore, Scanning Electron Microscopy (SEM) analysis was conducted to evaluate the degradation of fiber matrix interface. Results revealed that moisture, temperature and sustained load have a deteriorative impact on the performance of the composite.
{"title":"Combined Effect of Sustained Load and Harsh Environment on E-Glass/Epoxy Composites: Long Term Exposure","authors":"Amir Hussain Idrisi, Abdel Hamid Ismail Mourad","doi":"10.1115/pvp2022-84669","DOIUrl":"https://doi.org/10.1115/pvp2022-84669","url":null,"abstract":"\u0000 In this work, the durability of the E-glass/epoxy was investigated in terms of degradation in tensile properties and microstructure. Specimens were conditioned in seawater under sustained load and without load at 23 °C, 45 °C and 65 °C for the period of 15 months. The tensile strength of the E-glass/epoxy reduced gradually with immersion time. It reduced by 11% from 811 MPa to 721 MPa and by 18.2% from 811 MPa to 663 MPa for samples immersed without load and with 15% sustained load respectively. The respective reduction for 23°C and 45°C was 1.1% and 5.5% for samples without load and 6.2% and 11.3% for samples immersion under 15% sustained load after 15 months of exposure. The failure strain of E-glass/epoxy composite was slightly affected for the samples immersed without load during the period of 15 months but it was more noticeable under 15% sustained load at 65°C when the tensile strain reduced to 1.65% after 15 months of immersion. Furthermore, Scanning Electron Microscopy (SEM) analysis was conducted to evaluate the degradation of fiber matrix interface. Results revealed that moisture, temperature and sustained load have a deteriorative impact on the performance of the composite.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130043340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Stewart, J. Sulley, T. Warner, P. Wallace, G. Jones, D. Thatcher
This paper presents the work conducted by Rolls-Royce to investigate the mechanical and metallurgical properties of a Low Alloy Steel (LAS) grade 508 alloy batch of material. The material was manufactured using the Powder Metallurgy – Hot Isostatic Pressing (PM-HIP) method. The LAS was an ASME 508 4N model alloy. Rolls-Royce has used PM-HIP extensively for the manufacture of nuclear grade components such as valves, piping and pump bowls, and is now investigating its use for the manufacture of LAS pressure vessels in order to provide an alternative sourcing route to forgings to reduce costs and manufacturing lead-times. A key part of this work is to assess whether mechanical properties can be achieved that meet the specification requirements and that are also comparable to the forged equivalent. In this regard, the toughness of the material is of particular interest, with it being extremely important for LAS pressure vessel applications. This paper reports, that for this particular batch of material, the Charpy toughness was significantly below the minimum room temperature specification requirement, but that the tensile properties were well above the minimum specification requirements for proof and ultimate tensile strength. The Charpy toughness at room temperature was only at 38% of the specification requirement, and only at 21% of forged equivalent material. The reason for the poor Charpy results is potentially attributed to prior austenite retention given the highly faceted nature of the fracture faces and the size of the facet faces. Oxides and other precipitates, such as nitrides, are not believed to have significantly contributed to the low Charpy values in this powder batch. This is because inclusion assessments against other powder HIP material, which had exhibited higher Charpy values but produced with higher oxygen content, did not show a significantly different variation in non-metallic inclusion count, and there was no clear evidence of prior particle boundaries being evident in the cross-sectional studies of the microstructure. Hence, it is hypothesised that increased prior austenite formation was due to the increased nitrogen levels in the gas atomised powder.
{"title":"Mechanical Properties and Metallurgical Examination Results for a Batch of Powder Metallurgy - Hot Isostatically Pressed Low Alloy Steel Grade 508 4N","authors":"D. Stewart, J. Sulley, T. Warner, P. Wallace, G. Jones, D. Thatcher","doi":"10.1115/pvp2022-85077","DOIUrl":"https://doi.org/10.1115/pvp2022-85077","url":null,"abstract":"\u0000 This paper presents the work conducted by Rolls-Royce to investigate the mechanical and metallurgical properties of a Low Alloy Steel (LAS) grade 508 alloy batch of material. The material was manufactured using the Powder Metallurgy – Hot Isostatic Pressing (PM-HIP) method. The LAS was an ASME 508 4N model alloy. Rolls-Royce has used PM-HIP extensively for the manufacture of nuclear grade components such as valves, piping and pump bowls, and is now investigating its use for the manufacture of LAS pressure vessels in order to provide an alternative sourcing route to forgings to reduce costs and manufacturing lead-times. A key part of this work is to assess whether mechanical properties can be achieved that meet the specification requirements and that are also comparable to the forged equivalent. In this regard, the toughness of the material is of particular interest, with it being extremely important for LAS pressure vessel applications. This paper reports, that for this particular batch of material, the Charpy toughness was significantly below the minimum room temperature specification requirement, but that the tensile properties were well above the minimum specification requirements for proof and ultimate tensile strength. The Charpy toughness at room temperature was only at 38% of the specification requirement, and only at 21% of forged equivalent material. The reason for the poor Charpy results is potentially attributed to prior austenite retention given the highly faceted nature of the fracture faces and the size of the facet faces. Oxides and other precipitates, such as nitrides, are not believed to have significantly contributed to the low Charpy values in this powder batch. This is because inclusion assessments against other powder HIP material, which had exhibited higher Charpy values but produced with higher oxygen content, did not show a significantly different variation in non-metallic inclusion count, and there was no clear evidence of prior particle boundaries being evident in the cross-sectional studies of the microstructure. Hence, it is hypothesised that increased prior austenite formation was due to the increased nitrogen levels in the gas atomised powder.","PeriodicalId":434925,"journal":{"name":"Volume 4A: Materials and Fabrication","volume":"106 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2022-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121856941","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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