Thermal cycling of transition joints between modified 9Cr-1Mo steel and Alloy 800 for steam generator application
01 Dec 2002-International Journal of Pressure Vessels and Piping (Elsevier)-Vol. 79, Iss: 12, pp 819-827
TL;DR: In this paper, the effect of accelerated thermal cycling on a joint between modified 9Cr-1Mo steel (Grade 91) and Alloy 800 welded with Inconel 1 82 and 182 filler material is discussed.
About: This article is published in International Journal of Pressure Vessels and Piping.The article was published on 2002-12-01. It has received 30 citations till now. The article focuses on the topics: Austenitic stainless steel & Temperature cycling.
Citations
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TL;DR: In this paper, a comparative evaluation of an appropriate welding process and welding consumable is based on microstructural features, micro-hardness variation, tensile testing and fracture morphology.
67 citations
15 Jul 2015-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the dissimilar metal weld (DMW) joint between SA508Gr.3Cl.1 ferritic steel and SS304LN using Inconel 82/182 consumables was required in the nuclear power plants.
Abstract: The dissimilar metal weld (DMW) joint between SA508Gr.3Cl.1 ferritic steel and SS304LN using Inconel 82/182 consumables was required in the nuclear power plants. The joint integrity assessment of these welds requires mechanical and metallurgical properties evaluation in weldment regions. The joint was subjected to 100% radiography test and bend test and transverse tensile test. Welding and testing were carried out as per the requirements of ASME Sec-IX and acceptance criteria as per ASME Sec-III. The transverse tensile test results indicated the failure from the weld metal although it satisfies the minimum strength requirement of the ASME requirements; therefore, the DMW joint was analyzed in detail. Straight bead deposition technique, fine slag inclusion, less reliable radiograph technique, plastic instability stress, yield strength ratio and metallurgical deteriorations have been contributed to failure of the DMW joint from the weld region. In the present work, the factors contributing to the fracture from weld metal have been discussed and analyzed.
60 citations
TL;DR: In this paper, the microstructure and creep behavior of dissimilar weldment between the tempered martensitic steel T91 and the non-stabilized austenitic steel TP316H with Ni-based weld metal (Ni WM) were investigated using light microscopy, scanning and transmission electron microscopy and energy-dispersive X-ray spectroscopy.
45 citations
01 Jun 2016-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of Ni-Fe buffer layered buttering and welding processes on the resulting weld joints properties has been addressed, which leads to the development of more favourable properties than observed in welded joints made using the current practice without a buffer layer.
Abstract: In this study, we present the metallurgical and mechanical investigation of four dissimilar welds between SA508Gr.3Cl.1 and SS304LN. The welding processes for buttering deposition and fill-pass welding were varied with ERNiCr-3/ENiCrFe-3 consumables. The Ni-Fe alloy buffer layer was introduced as intermediate layer in buttering and then the joints (with and without buffer layer in buttering) were fabricated. The effect of Ni-Fe buffer layered buttering and welding processes on the resulting weld joints properties has been addressed. Metallurgical and mechanical properties, fracture toughness were measured and various examinations were carried out for integrity assessment on all the weld joints. Addition of a Ni-Fe buttering layer leads to the development of more favourable properties than observed in welded joints made using the current practice without a buffer layer. Control of carbon migration and its subsequent effect on metallurgical, mechanical properties due to buffer layer has been justified in the study. Conventional procedure of DMW fabrication has been proven to be the least favourable against the new technique suggested. Modification in current integrity assessment procedure would be possible by considering the properties at interfacial regions, introduction of yield strength ratio mismatch and the plastic instability strength in the integrity assessment.
43 citations
14 Jul 2020-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructure and mechanical properties of dissimilar metal weld joints between AISI 316L SS-Alloy 800 developed by activated TIG (A-TIG) welding are discussed.
Abstract: The present work discusses the microstructure and mechanical properties of dissimilar metal weld joint between AISI 316L SS-Alloy 800 developed by activated TIG (A-TIG) welding. The evolution of fusion zone microstructure and solidification temperature range were investigated through equilibrium calculation and Scheil-Gulliver equation. Electron probe micro-analysis revealed the micro-segregation of Ti and Si in the inter-dendritic arms of the fusion zone. The presence of secondary phases (Ti(C,N) and FeSi2) in the fusion zone was confirmed with X-ray diffraction technique and transmission electron microscopy of electrochemically extracted precipitates. The A-TIG weld joint showed a decent combination of tensile strength and impact toughness. Tensile testing with digital image correlation revealed a transfer of strain localization from Alloy 800 side heat affected zone to the fusion zone due to lower hardening capacity of the fusion zone. During tensile loading, the formation of micro-cracks along the solidification grain boundaries reduces the peak tensile strength of the fusion zone.
42 citations
References
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TL;DR: In this article, a trimetallic joint involving modified 9Cr-1Mo steel and 316LN austenitic stainless steel as the base materials and Alloy 800 as the intermediate piece was investigated.
150 citations
01 Nov 1977
TL;DR: In this paper, an improved transition weld joint between stainless steel and ferritic steel piping was developed to circumvent the failures and concerns with joints made by existing technology, and Alloy 800H was selected as an appropriate intermediate material for this application.
Abstract: The objective of this study was to develop an improved transition weld joint between stainless steel and ferritic steel piping to circumvent the failures and concerns with joints made by existing technology. The primary concern of mismatch in coefficients of thermal expansion between the ferritic and austenitic steels and the high stresses that it imposes at the interface between ferritic steel and weld metal led to an extensive elastic stress analysis involving base metal combinations, filler metals, and weld joint geometries. This analysis indicated that, for pipe welds, joint stress could be reduced considerably by using a transition material with an intermediate coefficient of thermal expansion between the 2 1/4 Cr-1 Mo ferritic steel and the austenitic stainless steel. Alloy 800H was selected as an appropriate intermediate material for this application.
25 citations
01 Jun 1983
TL;DR: In this paper, a simplified accelerated test procedure was developed for testing dissimilar-metal welds between austenitic stainless steels and low-alloy ferritic steels, which can be used as a screening procedure to compare the relative behavior of "improved" welds in future research and development programs.
Abstract: A simplified accelerated test procedure has been developed for testing dissimilar-metal welds between austenitic stainless steels and low-alloy ferritic steels. The failure of these welded joints in operating steam generators of fossil-fired power plants has become an increasing problem for the utility industry. The proposed test is a three-point loading, bent-beam test that uses sheet specimens taken from a dissimilar-metal weldment. Tests were conducted in a simple test fixture where the specimens are loaded with a set-screw. To determine whether the test produces the same type of failure as those produced in a power plant, tests were conducted on specimens taken from a weld between Type 316 stainless steel and 2 1/4 Cr-1 Mo steel plates using Type 309 stainless steel filler metal. The specimens were loaded in the test fixture at room temperature and then thermally cycled between room temperature and 593/sup 0/C (1099/sup 0/F) by placing the test apparatus in a box furnace (thermal cycling during power plant operation plays a major role in the weld failure during service). The specimens were kept in the furnace for 20 to 70 hours (h), cooled to room temperature, and then the cycle was repeated. Metallographic examination of specimens cycled asmore » few as 64 times with a total of 2300 h at 593/sup 0/C revealed that the specimens contained cracks similar to the cracks observed on dissimilar-metal welds cut from steam tubes after long-time elevated-temperature service racks similar to the cracks observed on dissimilar-metal welds cut from steam tubes after longtime elevated-temperature service in a fossil-fired steam generator. All indications are that this simple accelerated test could be used as a screening procedure to compare the relative behavior of ''improved'' welds in future research and development programs.« less
15 citations
TL;DR: In this article, the performance of a trimetallic transition joint was studied by accelerated thermal cycling of the Alloy 800/2.25Cr-1Mo steel joint after subjecting it to its optimum postweld heat treatment.
Abstract: The critical part of the transition metal joint between type 304 stainless steel and 2.25Cr-1Mo steel, with an immediate piece of Alloy 800, is the Alloy 800/2.25Cr-1Mo steel joint welded with Inconel 182. The performance of this trimetallic transition joint was studied by accelerated thermal cycling of the Alloy 800/2.25Cr-1Mo steel joint after subjecting it to its optimum post-weld heat treatment. The thermal cycling test procedure employed produces accelerated failures in transition metal joints similar to those observed in steam generators of operating power plants. The changes in the ferritic steel heat-affected zone on thermal cycling were also studied. The results of this study show that there is a marked improvement in performance, with at least a four-fold improvement in the life of the transition metal joint, on using the trimetallic configuration, instead of the direct (bimetallic) configuration.
13 citations
TL;DR: In this article, a pressure vessel, 153 mm outside diameter and 32 mm wall thickness, containing six dissimilar welds was tested under thermal cycling conditions, and the possible causes of the various deformation and cracking modes detected are discussed with particular reference to the applied loading system.
9 citations