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cross-weld joints
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Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 939-950, October 11–14, 2016,
... in respect to the alloy additions and microstructure. The mechanical properties of the weld metals at ambient temperature are examined. Creep properties of both undiluted weld metals and cross-weld joints are examined through stress rupture test and the data are evaluated and compared with those of the base...
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Despite the significant progress achieved in power generation technologies in the past two decades, finding effective solutions to further reduce emissions of harmful gases from thermal power plant still remains the major challenge for the power generation industry as well as alloy material developers. In the European material programmes COST 522 and COST 536, based on the existing 9-12%Cr creep resisting steels, an advanced 9%Cr-Mo martensitic alloy, C(F)B2 (GX13CrMoCoVNbNB9-2-1) alloy has been developed. By modification through alloying of boron and cobalt and together with other micro-adjustment of the composition, C(F)B2 alloys has showed very encouraging properties. The current paper summaries the development and evaluation of the matching filler metals for C(F)B2 grade. The design of the filler metal composition is discussed and comparison is made with the parent materials in respect to the alloy additions and microstructure. The mechanical properties of the weld metals at ambient temperature are examined. Creep properties of both undiluted weld metals and cross-weld joints are examined through stress rupture test and the data are evaluated and compared with those of the base alloy and other existing 9%Cr-Mo creep resisting steels.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 1109-1122, October 21–24, 2019,
... the filler materials had the smallest sub-grain structures. 1118 Figure 10: Macro hardness traverse for both X20 and P91 weld filler cross weld joints. Uniaxial tests Figure 11 illustrate creep curves (creep strain vs time) for cross weld samples that are consisted of creep aged X20 PM to X20 weld filler...
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Components such as tubes, pipes and headers used in power generation plants are operated in a creep regime and have a finite life. During partial replacement, creep exhausted materials are often welded to virgin materials with superior properties. The aim of this study was to identify a suitable weld filler material to join creep aged X20CrMoV12-1 to a virgin P91 (X10CrMoVNbV9-1) steel. Two dissimilar joints were welded using the gas tungsten arc welding (GTAW) process for the root passes, and manual metal arc (MMA) welding for filling and capping. The X20 and the P91 fillers were selected for joining the pipes. The samples were further heat treated at 755°C to stress relief the samples. Microstructural evolution and mechanical properties of the weld metals were evaluated. The average hardness of X20 weld metal (264 HV10) was higher than the hardness measurement of P91 weld metal (206 HV10). The difference in hardness was attributed to the high carbon content in X20 material. The characterisation results revealed that the use of either X20 or P91 weld filler for a butt weld of creep aged X20 and virgin P91 pipes material does not have a distinct effect on the creep life and creep crack propagation mechanism. Both weld fillers (X20 and P91) are deemed to be suitable because limited interdiffusion (<10 μm) of chromium and carbon at the dissimilar weld interface was observed across the fusion line. The presence of a carbon ‘denuded’ zone was limited to <10 μm in width, based on the results from local measurements of the precipitate phase fractions using image analysis and from elemental analysis using EDS. However the nanoindentation hardness measurements across the fusion line could not detect any ‘soft’ zone at the dissimilar weld interface. The effect of the minute denuded zone was also not evident when the samples were subjected to nanoindentation hardness testing, tensile mechanical testing, Small Punch Creep Test (SPCT) and cross weld uniaxial creep testing.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 530-553, August 31–September 3, 2010,
... temperature welded piping and headers around the world, the need to connect cross-weld data to weld joint design and assessment, and in general, the need to develop suitable guidelines for evaluating the strength of weldments relative to that of base metal. continuum damage mechanics headers high...
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The paper describes methods for practical high temperature weldment life assessment, and their application to the analysis of notable high energy piping weldment failures and interpretation of cross-weld data. The methods described in the paper are simplified versions of full continuum damage mechanics (CDM) analysis techniques which have been developed over the last 20 years. The complexity of the CDM methods and their data requirements has been a barrier to their more widespread use. The need for simplified methods has been driven by the need for risk assessment of in-service high temperature welded piping and headers around the world, the need to connect cross-weld data to weld joint design and assessment, and in general, the need to develop suitable guidelines for evaluating the strength of weldments relative to that of base metal.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 607-614, October 22–25, 2013,
... Abstract In order to clarify the effect of stress state on microstructural changes during creep, the microstructure was observed in the central part of the cross section of the fine-grained heat-affected zone (FGHAZ) and in the surface region of the FGHAZ in Gr.92 steel welded joint. Creep...
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In order to clarify the effect of stress state on microstructural changes during creep, the microstructure was observed in the central part of the cross section of the fine-grained heat-affected zone (FGHAZ) and in the surface region of the FGHAZ in Gr.92 steel welded joint. Creep tests were performed under constant load in air at 650°C, using cross-weld specimens. The creep strength of welded joint was lower than that of base metal. Type IV fracture occurred in the long-term. Creep voids were detected in the FGHAZ after the fracture. Number of creep voids was higher in the central part of the cross section of the FGHAZ than in the surface region of the FGHAZ. It was checked the multiaxiality of stress during creep was higher in the central part of the cross section of the FGHAZ than in the surface region of the FGHAZ. The recovery of dislocation structure occurred after creep in the base metal and the FGHAZ. Mean subgrain size increased with increasing time to rupture. However, there was no difference of change of subgrain size during creep in the central part of the cross section of the FGHAZ and in the surface region of the FGHAZ. The growth of M 23 C 6 carbide and MX carbonitrides was observed during creep in the base metal and the FGHAZ. Laves phase precipitation occurred during creep. There was no difference of the change of mean diameter of MX carbonitrides in the central part of the cross section of the FGHAZ and in the surface region of the FGHAZ after creep. However, the growth rate of M 23 C 6 carbide in the FGHAZ was much higher in the central part of the cross section than in the surface region.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 960-972, October 22–25, 2013,
... be presented based on the creep rupture data of the large size cross-weld specimens and component welds. creep degradation creep initiation creep life assessment fossil-fired power plants martensitic stainless steel steam temperature thermal efficiency weld joint influence factors welded metal...
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In order to improve thermal efficiency of fossil-fired power plants through increasing steam temperature and pressure high strength martensitic 9-12%Cr steels have extensively been used, and some power plants have experienced creep failure in high temperature welds after several years operations. The creep failure and degradation in welds of longitudinally seam-welded Cr- Mo steel pipes and Cr-Mo steel tubes of dissimilar metal welded joint after long-term service are also well known. The creep degradation in welds initiates as creep cavity formation under the multi-axial stress conditions. For the safety use of high temperature welds in power plant components, the complete understanding of the creep degradation and establishment of creep life assessment for the welds is essential. In this paper creep degradation and initiation mechanism in welds of Cr-Mo steels and high strength martensitic 9-12%Cr steels are reviewed and compared. And also since the non-destructive creep life assessment techniques for the Type IV creep degradation and failure in high strength martensitic 9-12%Cr steel welds are not yet practically established and applied, a candidate way based on the hardness creep life model developed by the authors would be demonstrated as well as the investigation results on the creep cavity formation behavior in the welds. Additionally from the aspect of safety issues on welds design an experimental approach to consider the weld joint influence factors (WJIF) would also be presented based on the creep rupture data of the large size cross-weld specimens and component welds.
Proceedings Papers
AM-EPRI2004, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Fourth International Conference, 788-802, October 25–28, 2004,
... loss and chemical composition of the consumables on the weld performance was studied. Short-term tensile and long-term creep tests on cross weld specimens were carried out in order to evaluate strength. The results obtained so far show that the properties of the welded joints are rather optimistic...
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Investigations on welded joints made from a modified parent material and welding consumables are described. Tubes and pipes with typical dimensions have been welded using different welding processes and consumables (GTAW, SAW, SMAW, modified filler metals). The influence of melting loss and chemical composition of the consumables on the weld performance was studied. Short-term tensile and long-term creep tests on cross weld specimens were carried out in order to evaluate strength. The results obtained so far show that the properties of the welded joints are rather optimistic, it could be assumed that the modified Alloy 617 and the welding consumables used will meet the requirements for use in a plant operated at ultra critical steam conditions with live steam temperatures up to 720°C and pressure up to 300 bar. This allows for first practical applications in test loops of plants. These applications including the Welding Procedure Qualifications are described.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 951-961, October 11–14, 2016,
... Properties at Ambient Temperature Table 7 shows the results of cross tensile tests and Charpy V-notch tests at ambient temperature. Both tensile samples fractured outside the weld metal on the CB2 side. Table 7: Mechanical properties of dissimilar joints CB2-P92 at ambient temperature Filler metal UTS [MPa...
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As flux cored wires for gas metal arc welding offer several technical and economic advantages they are becoming more and more popular. Matching flux cored wires for welding P92 have already been available for several years. A matching flux cored wire for welding the Co-alloyed cast steel CB2, which is used for turbine and valve casings operating at steam temperatures of up to 620°C, was developed recently. To connect casings with P92 pipes, dissimilar welding of CB2 to P92 is necessary. This can be done with filler metal that matches either CB2 or P92. Pre-tests have confirmed that flux cored arc welding (FCAW) can generally be used for dissimilar joint welding of CB2 to P92. To evaluate creep rupture strength dissimilar welds were performed with filler metal matching CB2 and P92, respectively. TIG welding was used for the root and the second pass and FCAW for the intermediate and final passes. Cross-weld tensile tests, side bend tests and impact tests of weld metals and heat-affected zones were carried out at ambient temperatures after two post-weld heat treatments (PWHT), each at 730°C for 12 hours. Creep rupture tests of cross-weld samples were performed at 625°C. This study compares the results of the mechanical tests at ambient temperature and the creep rupture tests, and discusses why P92 filler metals are preferred for such welds.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 667-678, October 22–25, 2013,
... of the cross-weld specimens made from the two joints are compared with each other as well as with those of the original pipe, i.e. BM A, as shown in Fig. 2. It can be seen that the two types of welded joints did not show a systematic difference between each other, both being weaker compared to the base metal...
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Creep rupture strength is the principal material property prioritized in designing power generation plants against the steady-state stress due to internal pressure. Increasingly plants must cycle so there is a possibility of life reduction due to creep-fatigue interaction. Grade 92 steel is one of the creep strength enhanced ferritic (CSEF) steels which has superior creep strength compared to other CSEFs. It is expected to be widely used in coal-fired ultra-super critical plants as well as in LNG-fired combined cycle plants. However, at present there is insufficient information regarding the creep-fatigue behavior of this material. A joint study has been conducted to understand the behavior of this steel under creep-fatigue condition and see how accurate the failure life can be estimated. Three kinds of base materials as well as two kinds of welded joints have been tested under strain-controlled cyclic loading with or without hold times as well as under constant load creep condition. Continued decrease in the number of cycles to failure was observed with the extension of hold time in all the base metals and cross-weld specimens. It was found that the modified ductility exhaustion approach based on inelastic strain, as well as its extension employing the inelastic strain energy density, made reasonably accurate predictions of failure lives under a wide range of test conditions. Temperature- and rate-dependencies of fracture limits in terms of inelastic strain and energy density were able to be uniquely expressed using simple thermal activation energy parameters.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 584-602, August 31–September 3, 2010,
... to develop a comprehensive database on the creep-fatigue behavior of Grade 92 steel's base metal and welded joints and to establish a suitable life estimation procedure. Key findings include: (i) a thick pipe with submerged arc welding (SAW) was manufactured for testing; (ii) base metal and cross-weld...
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Grade 92 steel, a creep strength-enhanced ferritic (CSEF) steel, is used in supercritical steam fossil power plants for boilers and piping systems. While its creep strength is crucial, understanding the interaction between creep and fatigue damage is also vital for assessing component integrity under cyclic loading. Despite existing studies on its creep-fatigue behavior, additional data under creep-dominant conditions relevant to plant evaluations are needed. Girth welds, critical to piping system integrity, are particularly important in this context. EPRI and CRIEPI initiated a project to develop a comprehensive database on the creep-fatigue behavior of Grade 92 steel's base metal and welded joints and to establish a suitable life estimation procedure. Key findings include: (i) a thick pipe with submerged arc welding (SAW) was manufactured for testing; (ii) base metal and cross-weld specimens showed similar behavior under short-term creep and cyclic loading; (iii) these specimens had lower creep strengths than average literature values for this steel class in the short time regime, with differences decreasing as stress decreased; and (iv) the fatigue and creep-fatigue behavior of these specimens were similar to those of Grade 91 and 122 steels, with common characteristics in creep-fatigue failure prediction models across the three CSEF steels.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 1069-1078, October 21–24, 2019,
... cool was carried out. The hardness and impact toughness of welded joints were measured, and the microstructure evolution after aging at 750℃ for 3000h was investigated by scanning electron microscopy(SEM). The results show that, during the aging process, the hardness of weld metal increases firstly...
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Nimonic 263 alloy was selected for gas turbine combustor transition piece due to its excellent high temperature mechanical performance. In present work, Nimonic 263 alloy plate with thickness of 5mm was welded using 263 filler metal by GTAW, then post weld heat treatment of 800℃/8h/air cool was carried out. The hardness and impact toughness of welded joints were measured, and the microstructure evolution after aging at 750℃ for 3000h was investigated by scanning electron microscopy(SEM). The results show that, during the aging process, the hardness of weld metal increases firstly and then decreases. The impact toughness decreases significantly at first and then increase. Furthermore, some fluctuations can be detected in hardness and impact toughness after long-term thermal exposure. The significant decrease in the impact toughness of the aged welded joints mainly results from the precipitation of η phase around grain boundary and intergranular MC phase. The hardness of weld metal increases due to the precipitation of more carbides and γ′ phase after 1000h aging, then decreases owing to the growth of γ′ phase after 3000h aging.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 948-959, October 22–25, 2013,
... 5Co1 and the post-weld heat treatment (PWHT) was applied. A cross-section of the welded joint is shown in Fig. 1. The results of tensile and impact tests at room temperature are shown in Tab. 3. The rod-shaped specimens (6.4 mm in diameter and 25.6 mm gauge length) were used for creep tests. The cross...
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The creep rupture properties of welded joints of advanced 9%Cr-Mo-Co-B steel used for 620°C USC steam turbine have been studied. The welded joints were prepared by means of shielded metal arc welding (SMAW). A lot of creep tests have been conducted and the results indicate that fracture usually occurs in the intercritical heat affected zone (ICHAZ) of the welded joint and is typical of Type IV cracking. The microstructure of the HAZ has been investigated by using optical microscopy, SEM and TEM. The degradation mechanism of welded joint of the 9%Cr-Mo-Co-B steel has been explored by analysing the phases of precipitates. Creep voids were observed in the vicinity of the coarse Laves phase particles, resulting in the degradation of the creep rupture properties.
Proceedings Papers
AM-EPRI2024, Advances in Materials, Manufacturing, and Repair for Power Plants: Proceedings from the Tenth International Conference, 582-591, October 15–18, 2024,
... is shown in Fig. 2. Figure 2: The cross-sectional profile of the modified DMW with a weld cap To be convenient, the joint using a narrow gap weld groove with ER NiCrCoMo-1 filler metal will be referred to as Type I, and the joint using a narrow gap weld groove with ER NiCr-3 filler metal will be referred...
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In this paper, the dissimilar metal welds (DMWs) between 617B nickel-based alloy and 10%Cr martensitic heat-resistant steel filled by 617 filler metal was studied, focused on the high temperature creep rupture properties. The high temperature creep rupture properties of welded joints with different welding processes were tested, and the microstructure of welded joints before and after the creep rupture test was observed by OM and SEM. The results showed that, there were three failure modes: base metal failure, type W failure and interface failure, among which interface failure caused the most serious life reduction. The welded joints using ER NiCr-3 filler metal reduced the strain concentration at the interface, so the fracture location shifted from the interface to HAZ of 10%Cr martensitic heat-resistant steel under high temperature and low stress conditions, and creep rupture life was improved. Similarly, weld cap shifted the creep crack propagation path by changing the groove form, so as to altered the stress state of joint and prolong the creep rupture life.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 1123-1131, October 21–24, 2019,
... was on the qualification and adaptation of welding processes, especially for thick-walled structures. For example the investigations in [1] showed that an optimization of the welding consumables for welded joints made of Alloy 617 aimed to avoid melting losses was successfully applied. Cross weld creep tests indicated...
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Welded joints of Ni-base alloys are often the critical part of components operated under high temperature service conditions. Especially welds in thick-walled structures are susceptible to various crack phenomena. Creep rupture and deformation behavior of different similar welds of Alloy 617B, both circumferential and longitudinal, were determined in many research German projects with the aim to qualify the nickel alloys and its welded joints for the use in highly efficient Advanced Ultra Supercritical (AUSC) power plants. Damage mechanisms and failure behavior have also been investigated within these projects. In order to reduce the welding residual stresses in thick-walled components a post weld heat treatment (PWHT) for Alloy 617B is recommended after welding. This PHWT reduces not only residual stresses but causes changes in the damage mechanisms and failure behavior of welded joints of Alloy 617B. Improving effects of PWHT have been investigated in this study and results of microstructural investigations were correlated with the material behavior.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 423-435, August 31–September 3, 2010,
... steel are deferent. It is necessary to perform intermediate aging at 840°C after welding to get high temperature ductility, but this aging decreases the strength of 12%Cr ferritic steel. Welding materials for high-strength dissimilar joints were designed using the CALPHAD method to solve the problem...
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A modified version of Alloy 706, designated FENIX-700, was developed using the CALPHAD method to improve high-temperature stability above 700°C. The new alloy features reduced Nb and increased Al content, relying on γ' (Ni 3 Al) strengthening while eliminating γ'' (Ni 3 Nb), δ, and η phases. This modification improved both creep temperature capability (from 650°C to 700°C) and segregation properties. Successful manufacturing trials included a 760 mm² forging shaft using triple melt processing and a 1050 mm ESR ingot, demonstrating industrial viability. The study also explores compatible Ni-base welding materials for joining FENIX-700 to 12% Cr ferritic steel in 700°C class steam turbine applications.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 161-168, October 11–14, 2016,
... for purpose of the transition joint by structural integrity assessment, additional mechanical test data, beyond the scope of ASME IX weld procedure qualification, was required. The range of mechanical testing included creep stress rupture testing (parent and cross weld), stress relaxation, cyclic stress...
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INCONEL 740H has been developed by Special Metals for use in Advanced Ultra Super Critical (A-USC) coal fired boilers. Its creep strength performance is currently amongst the ‘best in class’ of nickel based alloys, to meet the challenge of operating in typical A-USC steam temperatures of 700°C at 35 MPa pressure. Whilst the prime physical property of interest for INCONEL 740H has been creep strength, it exhibits other physical properties worthy of consideration in other applications. It has a thermal expansion co-efficient that lies between typical values for Creep Strength Enhanced Ferritic (CSEF) steels and austenitic stainless steels. This paper describes the validation work in support of the fabrication of a pipe transition joint that uses INCONEL 740H pipe, produced in accordance with ASME Boiler Code Case 2702, as a transition material to join P92 pipe to a 316H stainless steel header. The paper gives details of the material selection process, joint design and the verification process used for the joint.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 640-653, August 31–September 3, 2010,
... temperatures around 600°C, due to the dissolution of finely dispersed V-rich nitrides and the precipitation of coarse particles of the modified Z-phase, [(Cr,V,Nb)N]. Secondly, welded joints of nearly all ferritic steel grades are prone to premature creep failures in the fine-grained heat-affected zone, known...
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Ferritic 9-12 wt.% chromium steels are commonly used for thick-walled high-temperature components in thermal power plants, but they face two major limitations in high-temperature service. Firstly, a reduction in creep strength occurs after approximately 10,000 hours at service temperatures around 600°C, due to the dissolution of finely dispersed V-rich nitrides and the precipitation of coarse particles of the modified Z-phase, [(Cr,V,Nb)N]. Secondly, welded joints of nearly all ferritic steel grades are prone to premature creep failures in the fine-grained heat-affected zone, known as Type IV cracking, which results from a strength loss of up to 50% compared to the base material. This study describes the development of a 9Cr3W3CoVNb steel with added boron and controlled nitrogen content. Preliminary creep testing results up to 24,000 hours at 650°C show a significant improvement in creep strength compared to established ferritic 9Cr grades like P91 and P92, attributed to a reduced driving force for the precipitation of modified Z-phase particles. Crosswelds of the new 9Cr3W3CoVNbBN steel also demonstrate improved creep behavior at 650°C, with creep rupture strength comparable to the mean base material creep strength of the best commercially available grade P92.
Proceedings Papers
AM-EPRI2013, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Seventh International Conference, 690-701, October 22–25, 2013,
... was measured through the wall thickness. Fig. 1 shows a cross-sectional view of the intrados welded joint of the elbow and the areas in which the number density of creep voids was measured. The measurement results are given in Fig. 2. As indicated in Fig. 2, more creep voids were observed near the inner...
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Type IV damage was found at several ultra-supercritical (USC) plants that used creep-strength-enhanced ferritic (CSEF) steels in Japan, and the assessment of the remaining life of the CSEF steels is important for electric power companies. However, there has been little research on the remaining life of material that has actually served at a plant. In this study, the damage and remaining life of a Gr.91 welded elbow pipe that served for 54,000 h at a USC plant were investigated. First, microscopic observation and hardness testing were conducted on specimen cut from the welded joint; the results indicated that the damage to the elbow was more severe in the fine-grain heat-affected zone near the inner surface. Furthermore, creep rupture tests were performed using specimens cut from the welded joint of the elbow, and from these results, the remaining life was evaluated using the time fraction rule as almost 110,000 h. Finite-element analysis was also conducted to assess the damage and remaining life, and the results were compared with the experimental results.
Proceedings Papers
AM-EPRI2016, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Eighth International Conference, 931-938, October 11–14, 2016,
... Abstract Developed 9Cr-3W-3Co-Nd-B heat-resistant steel SAVE12AD (Recently designated as ASME Grade 93) pipes and tubes have higher creep strength in both base metal and welded joints than conventional high Cr ferritic steels such as ASME Grades 91, 92 and 122. The welded joints of SAVE12AD...
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Developed 9Cr-3W-3Co-Nd-B heat-resistant steel SAVE12AD (Recently designated as ASME Grade 93) pipes and tubes have higher creep strength in both base metal and welded joints than conventional high Cr ferritic steels such as ASME Grades 91, 92 and 122. The welded joints of SAVE12AD tubes with commercial filler wire for W62-10CMWV-Co (Gr. 92) or Ni base filler wire ERNiCr-3 (Alloy82) also have much better creep rupture strength than those of conventional steels because of suppression of refining in the Heat-Affected-Zone (HAZ). However, the creep rupture strength of weld metal of W62-10CMWV-Co was marginal. Additionally, the hot cracking susceptibility of weld metal using Ni base filler wire ERNiCr-3 was occasionally below the required level. Similar welding consumable for SAVE12AD has been developed to solve these problems. Optimization of nickel, neodymium and boron contents on similar welding consumable enables to obtain both the good long-term creep rupture strength and low enough hot cracking susceptibility of weld metal. Consequently, SAVE12AD welded joint is expected to be applied of piping and tubing above 600°C in USC power plants because of its good properties with similar welding consumable.
Proceedings Papers
AM-EPRI2010, Advances in Materials Technology for Fossil Power Plants: Proceedings from the Sixth International Conference, 1067-1076, August 31–September 3, 2010,
..., porosity or lack of fusion. 1069 Figure 3. Overview of the pipe after welding Figure 4(a) shows the macrostructure on the cross section of the weld joint. The multi-pass weld joint showed a good weld build-up layers without defects, and nearly parallel straight fusion lines. Hardness measurement...
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Continuous and active works have been going to develop 700°C A-USC (Advanced Ultra Super Critical) power plants in Europe, United States and also Japanese national project has launched in 2008. In this new Japanese project Fe-Ni based alloy HR6W (45Ni-24Fe-23Cr-7W-Ti) is one of the candidate materials for boiler tube and pipe as well as Ni based alloys such as well-known Alloy617, Alloy263 and Alloy740. The most important issue in boiler fabrication is the welding process of these alloys and long-term reliability of their weldments. Authors investigated the weldability of HR6W thick-wall pipe. The integrity of the weldment was confirmed with metallurgical investigation, mechanical testing and long term creep rupture test. It is proved that the narrow gap HST welding procedure can meet the requirements for Ni based or Fe-Ni based alloys and provides excellent strength properties.
Proceedings Papers
AM-EPRI2019, 2019 Joint EPRI – 123HiMAT International Conference on Advances in High-Temperature Materials, 1098-1108, October 21–24, 2019,
... Comparison of tensile properties between inner and outer surface 2.25Cr-1Mo base metal and weld metal The engineering stress-strain curves of 2.25Cr-1Mo base metal and cross-joint samples taken from the inner and outer walls are shown in Fig. 9. This study sample test temperature is 20 . There is no stress...
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Metallographic tests, micro-hardness tests, mechanics performance tests and Energy Dispersion Spectrum (EDS) were conducted for a 2.25Cr-1Mo main steam pipe weldment served for more than 32 years. Microstructural evolution of the 2.25Cr-1Mo base metal and weld metal was investigated. Degradation in micro-hardness and tensile properties were also studied. In addition, the tensile properties of subzones in the ex-service weldment were characterized by using miniature specimens. The results show that obvious microstructural changes including carbide coarsening, increasing inter lamella spacing and grain boundary precipitates occurred after long-term service. Degradation in micro-hardness is not obvious. However, the effects of long term service on tensile deformation behavior, ultimate tensile strength and yield stress are remarkable. Based on the yield stress of micro-specimens, the order of different subzones is: WM>HAZ>BM, which is consistent with the order of different subzones based on micro-hardness. However, the ultimate tensile strength and fracture strain of HAZ are lower than BM.
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