Results of a New Production of Nuclear-Grade 1.4970 ‘15-15Ti’ Stainless Steel Fuel Cladding Tubes for GEN IV Reactors

Titanium stabilized 1.4970 ‘15-15Ti’ stainless steel cladding is the primary choice for fuel cladding of several current fast spectrum research reactor projects. The choice of cladding material is based on past experiences and the availability of material databases from similar steel grades that have proven their reliability in past sodium-cooled fast reactors programs. However the last production in Europe of nuclear-grade 15-15Ti was more than 20 years ago and it remained to be seen if the know-how to produce such steel with the strict specifications for nuclear fuel cladding was still available. Results of a new production of nuclear-grade 15-15Ti cladding tubes at Sandvik for SCK•CEN is presented in this paper. It is shown that materials properties are within the strict specifications similar to the ones used during past sodium-cooled fast reactors programs. Special attention is given to microstructural analysis of the newly produced steel which contains a large number of stabilizing Ti(C-N) precipitates known for their beneficial effect on in-pile material properties and thermal creep. Results from metallography, SEM and TEM investigations are presented.

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15/15 Ti Stainless Steel Welding Process Optimization for GEN IV Nuclear Application in the GEMMA Project Frame

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.262 ◽

2021 ◽

Vol 1016 ◽

pp. 262-267

Author(s):

Giuseppe Barbieri ◽

Francesco Cognini ◽

Luciano Pilloni ◽

Daniele Mirabile Gattia ◽

Claudio Testani

Keyword(s):

Stainless Steel ◽

Welding Process ◽

Welding Parameters ◽

High Tendency ◽

Base Materials ◽

Nuclear Plants ◽

Steel Grades ◽

Gen Iv ◽

Past Experiences ◽

Welding Processes

This paper deals with activities carried out in the frame of GEMMA project on welded samples of 15/15 Ti stainless steel. The focus of GEMMA project has been on the investigation of material properties and associated welded joints for GEN IV nuclear plants. The RCC-MRx code uses the standard Base Metal Grade nomenclature (EN/ISO), but provides also additional specifications. Titanium stabilized “15-15Ti” stainless steel has been the primary choice for fuel cladding of current fast spectrum research reactor projects. The choice of cladding material is based on past experiences and the availability of material databases from similar steel grades proven in past sodium-cooled fast reactors programs [1-4]. On the basis of ENEA past experience, a strict specification has been written to realize a new heat treatment of this special stainless steel (SS). One of the main problems faced with this material is the high tendency to crack after the welding process. Several preliminary welding tests permitted to select TIG and laser welding processes for the 15/15 Ti SS. This fact because the main applications involve small thicknesses without filler material. The welding of the 15/15 Ti was performed using a fully automated TIG work station at ENEA CR-Casaccia. The base materials to evaluate the welding parameters were 15/15 Ti plates 100 X 170 X 3 mm welded under different shielding gas atmospheres and process parameters arrangements that permitted to obtain good quality joints avoiding catastrophic hot-cracking. The welded samples underwent a mechanical and metallographic characterization and the main results are here presented.

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On the feasibility of duplex stainless steel 2205 as an accident tolerant fuel cladding material for light water reactors

Journal of Nuclear Materials ◽

10.1016/j.jnucmat.2021.153265 ◽

2021 ◽

Vol 557 ◽

pp. 153265

Author(s):

Qian Xiao ◽

Chaewon Kim ◽

Changheui Jang ◽

Chaewon Jeong ◽

Hyunmyung Kim ◽

...

Keyword(s):

Stainless Steel ◽

Duplex Stainless Steel ◽

Light Water Reactors ◽

Fuel Cladding ◽

Light Water ◽

Water Reactors ◽

Cladding Material

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Assessment of Dissimilar Weld Between Duplex Stainless Steel Grades for Severe Corrosive Applications

Volume 2: Advanced Manufacturing ◽

10.1115/imece2017-72569 ◽

2017 ◽

Author(s):

Venkatesan Paranthaman ◽

K. Shanmuga Sundaram

Keyword(s):

Stainless Steel ◽

Duplex Stainless Steel ◽

Microstructural Analysis ◽

Welding Process ◽

Charpy Impact ◽

Dissimilar Welding ◽

Dissimilar Weld ◽

Steel Grades ◽

Steel Aisi ◽

Stainless Steel Aisi

This paper deals with the investigations on dissimilar weld between two duplex stainless steel grades AISI 2205 and AISI 2507. Increasing use of duplex stainless steel grades instead of austenitic stainless steel grades are growing day by day. This study is an effort in this direction in particularly focusing the dissimilar welding of super duplex stainless steel (AISI 2507) and commercial duplex stainless steel (AISI 2205) grades. Gas tungsten arc welding process was used in this study to fabricate the defect free weld plate. Microstructural analysis on dissimilar weld was carried out to study the diffusion of alloying elements. Micro hardness analysis, Charpy impact toughness test, tensile test and formability test were carried out and the properties were compared with their corresponding base metal properties. Hot corrosion test was carried out to study the feasibility of dissimilar weld in severe corrosive applications. The findings of this paper try to fulfill the applications where commercial duplex stainless steel grades are frequently gets affected in the weld region due to the severity of corrosive environments and due to the sacrificing weld properties.

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Review on Sodium Corrosion Evolution of Nuclear-Grade 316 Stainless Steel for Sodium-cooled Fast Reactor applications

Nuclear Engineering and Technology ◽

10.1016/j.net.2021.05.021 ◽

2021 ◽

Author(s):

Yaonan Dai ◽

Xiaotao Zheng ◽

Peishan Ding

Keyword(s):

Stainless Steel ◽

Fast Reactor ◽

Nuclear Grade ◽

316 Stainless Steel

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Impact of Solidification on Inclusion Morphology in ESR and PESR Remelted Martensitic Stainless Steel Ingots

Metals ◽

10.3390/met11030408 ◽

2021 ◽

Vol 11 (3) ◽

pp. 408

Author(s):

Ewa Sjöqvist Persson ◽

Sofia Brorson ◽

Alec Mitchell ◽

Pär G. Jönsson

Keyword(s):

Stainless Steel ◽

Martensitic Stainless Steel ◽

Dendritic Structure ◽

Steel Grade ◽

Solidification Structure ◽

Production Scale ◽

Steel Grades ◽

Steel Ingots ◽

Columnar Dendritic Structure ◽

The Impact

This study focuses on the impact of solidification on the inclusion morphologies in different sizes of production-scale electro-slag remelting (ESR) and electro-slag remelting under a protected pressure-controlled atmosphere, (PESR), ingots, in a common martensitic stainless steel grade. The investigation has been carried out to increase the knowledge of the solidification and change in inclusion morphologies during ESR and PESR remelting. In order to optimize process routes for different steel grades, it is important to define the advantages of different processes. A comparison is made between an electrode, ESR, and PESR ingots with different production-scale ingot sizes, from 400 mm square to 1050 mm in diameter. The electrode and two of the smallest ingots are from the same electrode charge. The samples are taken from both the electrode, ingots, and rolled/forged material. The solidification structure, dendrite arm spacing, chemical analyzes, and inclusion number on ingots and/or forged/rolled material are studied. The results show that the larger the ingot and the further towards the center of the ingot, the larger inclusions are found. As long as an ingot solidifies with a columnar dendritic structure (DS), the increase in inclusion number and size with ingot diameter is approximately linear. However, at the ingot size (1050 mm in diameter in this study) when the center of the ingot converts to solidification in the equiaxial mode (EQ), the increase in number and size of the inclusions is much higher. The transition between a dendritic and an equiaxial solidification in the center of the ingots in this steel grade takes place in the region between the ingot diameters of 800 and 1050 mm.

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