R. B. Rebak, Liang Yin, M. Larsen, R. Umretiya, A. Hoffman
Iron-chromium-aluminum (FeCrAl) alloys are being characterized to be used in light water reactors for the cladding of the fuel. The use of accident tolerant fuel (ATF) such as FeCrAl alloys would allow for reactors operating safer, more economically, and for an extending life beyond 60 years. It was shown before that the lower or 12%Cr alloy such as C26M may have higher corrosion rate than the higher 21%Cr APMT. This article shows that the addition of a small amount of zinc (Zn) into the water reduces by more than 60% the dissolution rate of the FeCrAl. Zn incorporates into the external layer of the oxide film making the alloy more resistant to dissolution.
{"title":"Mitigating LWR IronClad Fuel Cladding Dissolution Using Zinc Water Chemistry","authors":"R. B. Rebak, Liang Yin, M. Larsen, R. Umretiya, A. Hoffman","doi":"10.1115/pvp2022-80559","DOIUrl":"https://doi.org/10.1115/pvp2022-80559","url":null,"abstract":"\u0000 Iron-chromium-aluminum (FeCrAl) alloys are being characterized to be used in light water reactors for the cladding of the fuel. The use of accident tolerant fuel (ATF) such as FeCrAl alloys would allow for reactors operating safer, more economically, and for an extending life beyond 60 years. It was shown before that the lower or 12%Cr alloy such as C26M may have higher corrosion rate than the higher 21%Cr APMT. This article shows that the addition of a small amount of zinc (Zn) into the water reduces by more than 60% the dissolution rate of the FeCrAl. Zn incorporates into the external layer of the oxide film making the alloy more resistant to dissolution.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"70 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":"122648742","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}
There is enthusiasm for new civil nuclear plants in the UK to adopt power beam welding technologies, which could offer several advantages over conventional techniques. In particular, reduction in the time taken to produce and inspect a weld, and thus the cost of manufacturing components. However, a blocker to the adoption of these technologies is a shortage of accepted methodologies for demonstrating the integrity of these joints, which forms part of the requirements of the generic design assessment within the UK regulatory environment. Residual stresses can contribute towards crack driving force and thus should be accounted for when assessing the integrity of a component or its tolerance to damage. Whilst bounding residual stress fields are often used, it is often desirable to have more realistic estimations that capture the through-wall residual stress distribution, which also allows them to be decomposed into membrane, bending and self-equilibrated components to aid stress classification. Material-specific weld residual stress profiles already exist, for example Level 3 profiles in the UK’s R6 procedure. However, they are for arc welding techniques. This work seeks to provide a framework for the generation of weld residual stress profiles for power beam welds and is split over two papers: 1. Weld Production, Residual Stress Measurements and Predictions; 2. A Methodology and Example for Parameterised Residual Stress Profiles. In this paper an experimentally-validated programme of weld modelling is presented to be used as an input to the framework for producing parametric through-thickness weld residual stress profiles presented in the second paper.
{"title":"Electron Beam Welds in 316L Part 1: Weld Production, Residual Stress Measurements and Predictions","authors":"G. Horne, Andrew Moffat","doi":"10.1115/pvp2022-84779","DOIUrl":"https://doi.org/10.1115/pvp2022-84779","url":null,"abstract":"\u0000 There is enthusiasm for new civil nuclear plants in the UK to adopt power beam welding technologies, which could offer several advantages over conventional techniques. In particular, reduction in the time taken to produce and inspect a weld, and thus the cost of manufacturing components. However, a blocker to the adoption of these technologies is a shortage of accepted methodologies for demonstrating the integrity of these joints, which forms part of the requirements of the generic design assessment within the UK regulatory environment.\u0000 Residual stresses can contribute towards crack driving force and thus should be accounted for when assessing the integrity of a component or its tolerance to damage. Whilst bounding residual stress fields are often used, it is often desirable to have more realistic estimations that capture the through-wall residual stress distribution, which also allows them to be decomposed into membrane, bending and self-equilibrated components to aid stress classification.\u0000 Material-specific weld residual stress profiles already exist, for example Level 3 profiles in the UK’s R6 procedure. However, they are for arc welding techniques. This work seeks to provide a framework for the generation of weld residual stress profiles for power beam welds and is split over two papers:\u0000 1. Weld Production, Residual Stress Measurements and Predictions;\u0000 2. A Methodology and Example for Parameterised Residual Stress Profiles.\u0000 In this paper an experimentally-validated programme of weld modelling is presented to be used as an input to the framework for producing parametric through-thickness weld residual stress profiles presented in the second paper.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"135 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":"117332383","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}
HY-80 is a quenched and tempered high strength low alloy steel developed for use in naval applications, specifically for the submarine pressure hulls. Properly developed welding procedures and correct welding consumable selection are important for obtaining quality welds for HY-80 welding, especially when metal thickness is 50 mm and over. Welding procedure qualification on 50 mm thick high strength HY-80 steel was performed using the mechanized flux cored arc welding (FCAW) process. A series of procedure qualification test panels were fabricated. Non-destructive examinations (NDE) and mechanical testing of the qualification panels were performed in accordance with the requirements of the applicable MOD UK standards. Through detailed analysis of the welding parameters, mechanical properties, microstructures and NDE results of the test panels, this paper provides insight into the effects of welding process variables on mechanical properties and weld quality of heavy wall HY-80 welding.
{"title":"High Strength Heavy Wall HY-80 Flux Cored Arc Welding","authors":"D. Sun, B. Johnstone","doi":"10.1115/pvp2022-84987","DOIUrl":"https://doi.org/10.1115/pvp2022-84987","url":null,"abstract":"\u0000 HY-80 is a quenched and tempered high strength low alloy steel developed for use in naval applications, specifically for the submarine pressure hulls. Properly developed welding procedures and correct welding consumable selection are important for obtaining quality welds for HY-80 welding, especially when metal thickness is 50 mm and over.\u0000 Welding procedure qualification on 50 mm thick high strength HY-80 steel was performed using the mechanized flux cored arc welding (FCAW) process. A series of procedure qualification test panels were fabricated. Non-destructive examinations (NDE) and mechanical testing of the qualification panels were performed in accordance with the requirements of the applicable MOD UK standards.\u0000 Through detailed analysis of the welding parameters, mechanical properties, microstructures and NDE results of the test panels, this paper provides insight into the effects of welding process variables on mechanical properties and weld quality of heavy wall HY-80 welding.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"18 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":"123622848","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}
The performance of static casting 25Cr35NiNb alloy pipe fittings with complex shapes for ethylene cracking furnace is insufficient, which affects the safe operation of equipment, and becomes an urgent problem to be solved in this field. Laser additive manufacturing (LAM) technique is suitable for the fabrication of complex components with high performance. 25Cr35NiNb alloy prepared by LAM is different from that prepared by static casting or centrifugal casting due to the solidification with the cooling rate of 102∼105 K/s in a tiny molten pool. In order to fabricate complex pipe fittings by LAM, the performance of 25Cr35NiNb alloy prepared by LAM needs to be clarified and the mechanism also needs to be revealed. This paper focuses on the mechanism of high temperature stability on microstructures of 25Cr35NiNb alloy prepared by LAM. Firstly, two kinds of 25Cr35NiNb alloy deposits were prepared by LAM with different processing parameters. Secondly, heat treatments were executed in the temperature range from 850°C to 1275°C for 25Cr35NiNb alloy deposits. Then, the microstructures of 25Cr35NiNb alloy were observed by optical microscope (OM) and scanning electron microscopy (SEM). It is found that the finer the microstructures of the original deposits was, the better the high temperature stability of microstructures was. The results of electron probe microanalysis (EPMA) show that the distribution of Nb and Ti elements in the original deposits affects the high temperature stability of microstructures. The finer microstructure has the more uniform distribution of Nb and Ti elements, which improves the high temperature microstructural stability.
{"title":"Mechanism of High Temperature Stability on Microstructures of 25Cr35NiNb Alloy Prepared by Laser Additive Manufacturing","authors":"Jizhan Li, Z. Fan, Tao Chen, Yu Zhou","doi":"10.1115/pvp2022-84663","DOIUrl":"https://doi.org/10.1115/pvp2022-84663","url":null,"abstract":"\u0000 The performance of static casting 25Cr35NiNb alloy pipe fittings with complex shapes for ethylene cracking furnace is insufficient, which affects the safe operation of equipment, and becomes an urgent problem to be solved in this field. Laser additive manufacturing (LAM) technique is suitable for the fabrication of complex components with high performance. 25Cr35NiNb alloy prepared by LAM is different from that prepared by static casting or centrifugal casting due to the solidification with the cooling rate of 102∼105 K/s in a tiny molten pool. In order to fabricate complex pipe fittings by LAM, the performance of 25Cr35NiNb alloy prepared by LAM needs to be clarified and the mechanism also needs to be revealed.\u0000 This paper focuses on the mechanism of high temperature stability on microstructures of 25Cr35NiNb alloy prepared by LAM. Firstly, two kinds of 25Cr35NiNb alloy deposits were prepared by LAM with different processing parameters. Secondly, heat treatments were executed in the temperature range from 850°C to 1275°C for 25Cr35NiNb alloy deposits. Then, the microstructures of 25Cr35NiNb alloy were observed by optical microscope (OM) and scanning electron microscopy (SEM). It is found that the finer the microstructures of the original deposits was, the better the high temperature stability of microstructures was. The results of electron probe microanalysis (EPMA) show that the distribution of Nb and Ti elements in the original deposits affects the high temperature stability of microstructures. The finer microstructure has the more uniform distribution of Nb and Ti elements, which improves the high temperature microstructural stability.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"21 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":"126485242","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}
Failure in pipes containing an initial crack under multi-axial loading condition is of common occurrence in industry and engineering applications. Current fitness-for-service codes and design standards cover partially part of this complex type of failure mode where the stress states may change abruptly from one state to another due to the combinatory nature of the applied loads. However, the torsional moment is mostly disregarded in the analysis for being apparently negligible in front of the bending moment and axial force, whose combined effects on crack-tip stress-strain fields have been very well investigated in the past. Based on recent research efforts to understand its effect, it has found that torsion in combination with axial force and bending moment, in fact, increases structural strength and delay fracture propagation, whose intensity varies depending on the crack configurations. Inspired by previous observations, this work takes a step forward in understanding effects of combined torsion with bending and axial force under harsh environments such as low temperature levels. A comprehensive numerical investigation is carried out using a newly developed constitutive model to describe failure at low temperatures on multi-axially loaded cracked pipes made of 316L stainless steel. Kinetic phase transformation and temperature dependent fracture criterion are implemented to accurately capture mechanical response at different temperature levels. Even though, experimental observations of these simulations were not available, their outcomes were quite consistent with some already published results performed on similar materials and loading conditions.
{"title":"Numerical Investigation of Ductile Crack Propagation of Circumferentially Cracked Pipes Subjected to Multiaxial Loading at Room and Low Temperatures","authors":"Yuhao Li, M. Paredes","doi":"10.1115/pvp2022-84788","DOIUrl":"https://doi.org/10.1115/pvp2022-84788","url":null,"abstract":"\u0000 Failure in pipes containing an initial crack under multi-axial loading condition is of common occurrence in industry and engineering applications. Current fitness-for-service codes and design standards cover partially part of this complex type of failure mode where the stress states may change abruptly from one state to another due to the combinatory nature of the applied loads. However, the torsional moment is mostly disregarded in the analysis for being apparently negligible in front of the bending moment and axial force, whose combined effects on crack-tip stress-strain fields have been very well investigated in the past. Based on recent research efforts to understand its effect, it has found that torsion in combination with axial force and bending moment, in fact, increases structural strength and delay fracture propagation, whose intensity varies depending on the crack configurations. Inspired by previous observations, this work takes a step forward in understanding effects of combined torsion with bending and axial force under harsh environments such as low temperature levels. A comprehensive numerical investigation is carried out using a newly developed constitutive model to describe failure at low temperatures on multi-axially loaded cracked pipes made of 316L stainless steel. Kinetic phase transformation and temperature dependent fracture criterion are implemented to accurately capture mechanical response at different temperature levels. Even though, experimental observations of these simulations were not available, their outcomes were quite consistent with some already published results performed on similar materials and loading conditions.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"4 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":"126568025","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}
Jun-Min Seo, H. Kim, Yun‐Jae Kim, H. Yamada, T. Kumagai, Hayato Tokunaga, N. Miura
In this study, Johnson-Cook fracture strain model considering the effect of stress triaxiality and strain rate is determined for austenitic stainless steel 304. Tensile test data of four different stress triaxiality and six different strain rate conditions are used to determine the parameters in the J-C fracture strain model. To see the effect of local variation of stress triaxiality and strain rate in the specimen, the J-C fracture models are determined in two different ways. The first case uses the initial stress triaxiality and nominal strain rate, and the second case uses the average value of local stress triaxiality and strain rate obtained from finite element analysis. The use of initial stress triaxiality gives conservative estimate of fracture strain at low stress triaxiality, and non-conservative estimate at high stress triaxiality. The use of nominal strain rate gives overall conservative estimate of fracture strain.
{"title":"Determination of Johnson-Cook Fracture Strain Model for Austenitic Stainless Steel 304","authors":"Jun-Min Seo, H. Kim, Yun‐Jae Kim, H. Yamada, T. Kumagai, Hayato Tokunaga, N. Miura","doi":"10.1115/pvp2022-83772","DOIUrl":"https://doi.org/10.1115/pvp2022-83772","url":null,"abstract":"\u0000 In this study, Johnson-Cook fracture strain model considering the effect of stress triaxiality and strain rate is determined for austenitic stainless steel 304. Tensile test data of four different stress triaxiality and six different strain rate conditions are used to determine the parameters in the J-C fracture strain model. To see the effect of local variation of stress triaxiality and strain rate in the specimen, the J-C fracture models are determined in two different ways. The first case uses the initial stress triaxiality and nominal strain rate, and the second case uses the average value of local stress triaxiality and strain rate obtained from finite element analysis. The use of initial stress triaxiality gives conservative estimate of fracture strain at low stress triaxiality, and non-conservative estimate at high stress triaxiality. The use of nominal strain rate gives overall conservative estimate of fracture strain.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"61 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":"127230055","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}
The use of residual stress information in probabilistic fracture assessments is hindered by difficulties in the quantification of uncertainty. At the same time, it is often necessary to consider residual stress data derived via two or more independent methods in an assessment: typically from a model of the process which introduced the stress, and from a direct physical measurement. The uncertainty in single weld process models is difficult to quantify and is strongly dependent on the process being modelled, the material constitutive behaviour assumed, and so on. Likewise, most experimental techniques for measuring deep residual stresses on welded metallic components, including relaxation methods such as Deep Hole Drilling and diffraction-based methods, also have multiple physical sources of uncertainty associated with them. This makes the uncertainty associated with single measurements difficult to estimate reliably. We explore the use of inverse-variance weighting to combine such datasets through “characteristic” uncertainties derived from prior round robin studies, and we use data from the NeT TG4 residual stress measurement and modelling round robin to illustrate this approach. Although it requires some significant simplifications, it allows convenient synthesis of residual stress data while gaining more realistic uncertainty estimates than are typically available from single measurements. This is significant because straightforward yet robust uncertainty estimates will be key for enabling future structural integrity assessment methodologies.
{"title":"Combining Weld Residual Stress Predictions and Measurement for Use in Probabilistic Structural Integrity Assessments","authors":"H. Coules, C. Simpson, M. Mostafavi","doi":"10.1115/pvp2022-84741","DOIUrl":"https://doi.org/10.1115/pvp2022-84741","url":null,"abstract":"\u0000 The use of residual stress information in probabilistic fracture assessments is hindered by difficulties in the quantification of uncertainty. At the same time, it is often necessary to consider residual stress data derived via two or more independent methods in an assessment: typically from a model of the process which introduced the stress, and from a direct physical measurement. The uncertainty in single weld process models is difficult to quantify and is strongly dependent on the process being modelled, the material constitutive behaviour assumed, and so on. Likewise, most experimental techniques for measuring deep residual stresses on welded metallic components, including relaxation methods such as Deep Hole Drilling and diffraction-based methods, also have multiple physical sources of uncertainty associated with them. This makes the uncertainty associated with single measurements difficult to estimate reliably.\u0000 We explore the use of inverse-variance weighting to combine such datasets through “characteristic” uncertainties derived from prior round robin studies, and we use data from the NeT TG4 residual stress measurement and modelling round robin to illustrate this approach. Although it requires some significant simplifications, it allows convenient synthesis of residual stress data while gaining more realistic uncertainty estimates than are typically available from single measurements. This is significant because straightforward yet robust uncertainty estimates will be key for enabling future structural integrity assessment methodologies.","PeriodicalId":434862,"journal":{"name":"Volume 4B: 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":"130463380","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}
Anomalous and inconsistent results were observed while performing fatigue crack growth tests in hydrogen gas on 4130X Cr-Mo steel when the stress-intensity factor range (ΔK) was less than 10 MPa m1/2. Two particular abnormal characteristics were noted: i) sequential measurements of fatigue crack growth rate (da/dN) vs. ΔK from a single test specimen were not repeatable at lower ΔK, and ii) at constant ΔK ∼8 MPa m1/2, da/dN never reached a steady-state level, as crack growth rates continuously increased as a function of time. It was hypothesized that both of these characteristics could be related to water vapor in the hydrogen gas. This hypothesis was tested by varying the environment in the test chamber through modification of the pressure purging and vacuum evacuation procedures. The resulting water vapor levels in the hydrogen test gas were either higher or lower than the nominal value, and measurements of fatigue crack growth rates in these environments confirmed the hypothesis that water vapor governed da/dN at lower ΔK. One consequence of such water vapor-dominated fatigue crack growth rates is that the da/dN vs. ΔK relationship in dry hydrogen gas at lower ΔK cannot be reliably represented by the da/dN vs. ΔK relationship measured in humid air. As a result, when the lower-ΔK portion of the da/dN vs. ΔK relationship in hydrogen gas is constructed from the da/dN vs. ΔK relationship in air, fatigue crack growth rates can be overestimated by as much as an order of magnitude.
对4130X Cr-Mo钢在氢气中进行疲劳裂纹扩展试验时，应力强度因子范围(ΔK)小于10 MPa m1/2时，出现了异常且不一致的结果。注意到两个特殊的异常特征:i)单个试样的疲劳裂纹扩展速率(da/dN)与ΔK的连续测量在较低的ΔK下是不可重复的，ii)在恒定的ΔK ~ 8 MPa m1/2下，da/dN从未达到稳态水平，因为裂纹扩展速率作为时间的函数不断增加。据推测，这两种特征都可能与氢气中的水蒸气有关。这一假设是通过改变试验室内的环境，通过修改压力净化和真空疏散程序来验证的。由此产生的氢气测试气体中的水蒸气水平高于或低于标称值，并且在这些环境中对疲劳裂纹扩展速率的测量证实了水蒸气在较低ΔK下控制da/dN的假设。这种以水蒸气为主导的疲劳裂纹扩展速率的一个后果是，在低ΔK的干氢气中，da/dN与ΔK的关系不能用在潮湿空气中测量的da/dN与ΔK的关系来可靠地表示。因此，当氢气中da/dN vs. ΔK关系的较低-ΔK部分由空气中的da/dN vs. ΔK关系构建时，疲劳裂纹扩展速率可能被高估多达一个数量级。
{"title":"Effect of Trace Water Vapor on Measurement of Fatigue Crack Growth Rates in Hydrogen Gas at Low ΔK","authors":"K. Nibur, B. Somerday","doi":"10.1115/pvp2022-84879","DOIUrl":"https://doi.org/10.1115/pvp2022-84879","url":null,"abstract":"\u0000 Anomalous and inconsistent results were observed while performing fatigue crack growth tests in hydrogen gas on 4130X Cr-Mo steel when the stress-intensity factor range (ΔK) was less than 10 MPa m1/2. Two particular abnormal characteristics were noted: i) sequential measurements of fatigue crack growth rate (da/dN) vs. ΔK from a single test specimen were not repeatable at lower ΔK, and ii) at constant ΔK ∼8 MPa m1/2, da/dN never reached a steady-state level, as crack growth rates continuously increased as a function of time. It was hypothesized that both of these characteristics could be related to water vapor in the hydrogen gas. This hypothesis was tested by varying the environment in the test chamber through modification of the pressure purging and vacuum evacuation procedures. The resulting water vapor levels in the hydrogen test gas were either higher or lower than the nominal value, and measurements of fatigue crack growth rates in these environments confirmed the hypothesis that water vapor governed da/dN at lower ΔK. One consequence of such water vapor-dominated fatigue crack growth rates is that the da/dN vs. ΔK relationship in dry hydrogen gas at lower ΔK cannot be reliably represented by the da/dN vs. ΔK relationship measured in humid air. As a result, when the lower-ΔK portion of the da/dN vs. ΔK relationship in hydrogen gas is constructed from the da/dN vs. ΔK relationship in air, fatigue crack growth rates can be overestimated by as much as an order of magnitude.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"7 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":"133620123","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 test specimens were prepared and tested with an API 5L X70 spiral welded pipe steel and girth weld. For a few selected specimens, two unloading compliance techniques (elastic compliance and back-face strain compliance) were applied simultaneously to a single specimen for direct comparisons of in-situ crack size estimation. This paper also includes fatigue crack growth rate (FCGR) data of other pipe steels and welds available in the literature. It was observed that most FCGR curves of pipeline steels (X65∼X100) remained within the BS 7910 mean and upper bound design curves in the Paris region. On the contrary, the fatigue crack growth rate of the X42 pipeline steel from a reference was high — a very steep slope of the FCGR curve, crossing over the BS 7910 design criteria. It was noted that the FCGR of austenitic stainless pipe steel and girth weld obtained from Arora et al. (2014) showed a very excellent fatigue property.
采用API 5L X70螺旋焊管钢和环焊缝制备了疲劳试验试样。对选取的少数试件，同时采用弹性柔度和后面应变柔度两种卸载柔度技术对单个试件进行原位裂纹尺寸估算的直接比较。本文还包括文献中其他管材和焊缝的疲劳裂纹扩展速率(FCGR)数据。在巴黎地区，大多数管道钢(X65 ~ X100)的FCGR曲线保持在BS 7910的平均值和上限设计曲线内。相反，参考的X42管线钢的疲劳裂纹扩展速率很高——FCGR曲线的斜率非常陡，超过了BS 7910设计标准。值得注意的是，Arora et al.(2014)获得的奥氏体不锈钢管钢和环焊缝的FCGR表现出非常优异的疲劳性能。
{"title":"Fatigue Crack Growth Assessment of Pipeline Steels and Girth Welds","authors":"D. Park, Jie Liang, J. Gravel","doi":"10.1115/pvp2022-80320","DOIUrl":"https://doi.org/10.1115/pvp2022-80320","url":null,"abstract":"\u0000 Fatigue test specimens were prepared and tested with an API 5L X70 spiral welded pipe steel and girth weld. For a few selected specimens, two unloading compliance techniques (elastic compliance and back-face strain compliance) were applied simultaneously to a single specimen for direct comparisons of in-situ crack size estimation. This paper also includes fatigue crack growth rate (FCGR) data of other pipe steels and welds available in the literature. It was observed that most FCGR curves of pipeline steels (X65∼X100) remained within the BS 7910 mean and upper bound design curves in the Paris region. On the contrary, the fatigue crack growth rate of the X42 pipeline steel from a reference was high — a very steep slope of the FCGR curve, crossing over the BS 7910 design criteria. It was noted that the FCGR of austenitic stainless pipe steel and girth weld obtained from Arora et al. (2014) showed a very excellent fatigue property.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"303 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":"133090907","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 cryogenic process plants that use aluminum alloy brazed core exchangers, a transition to austenitic stainless steel piping is often required. Presently, multi-layered explosion bonded piping joints provide that joint. These joints employ multiple layers of different alloys (e.g. 304L SS, Ni 200, Ti, Al, and Al-Mg), to provide the required leak-tight joint. Analysis of a few recent failures of these joints have shown interesting properties on a micro scale within the nickel layer, adjacent to the titanium-nickel interface. This paper will discuss the morphology of cracks, and discuss potential causes.
{"title":"Unique Failures in Explosion Bond Cryogenic Transition Joints","authors":"R. Colwell","doi":"10.1115/pvp2022-80411","DOIUrl":"https://doi.org/10.1115/pvp2022-80411","url":null,"abstract":"\u0000 In cryogenic process plants that use aluminum alloy brazed core exchangers, a transition to austenitic stainless steel piping is often required. Presently, multi-layered explosion bonded piping joints provide that joint. These joints employ multiple layers of different alloys (e.g. 304L SS, Ni 200, Ti, Al, and Al-Mg), to provide the required leak-tight joint.\u0000 Analysis of a few recent failures of these joints have shown interesting properties on a micro scale within the nickel layer, adjacent to the titanium-nickel interface. This paper will discuss the morphology of cracks, and discuss potential causes.","PeriodicalId":434862,"journal":{"name":"Volume 4B: Materials and Fabrication","volume":"4 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":"123925420","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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