RT Journal Article
T1 Secondary Phases Quantification and Fracture Toughness at Cryogenic Temperature of Austenitic Stainless Steel Welds for High-Field Superconducting Magnets
A1 Avilés Santillana, Ignacio
A1 Fernández Pisón, María del Pilar
A1 Langeslag, Stefanie
A1 Sgobba, Stefano
A1 Lunt, Alexander
A1 Boyer, Christelle
A1 Ruiz Navas, Elisa María
AB The ITER magnet system is based on the "cable-inconduit" conductor concept, which consists of various types of stainless steel jackets filled with superconducting strands. The jackets provide high strength and fracture toughness to counteract the high stress imposed by, amongst others, electromagnetic loads at cryogenic temperature. Material properties of austenitic stainless steel at cryogenic temperature are known to some extent, but only partial information is available for their welds, particularly in combination with weld fillers envisaged for cryogenic service. When a full inspection of the welded components is not possible, it becomes of special interest an assessment of its fracture toughness under close-to-service conditions if a fracture mechanics' design approach is to be adopted. In absence of defects, brittle secondary phases are generally held responsible of the loss of ductility and toughness which is to be expected after postweld heat treatments. Their quantification becomes thus essential in order to explain the negative impact in fracture toughness after unavoidable thermal treatments. This paper investigates fracture toughness behavior at 7 K of AISI 316L and AISI 316LN tungsten inert gas welds using two fillers adapted to cryogenic service, EN 1.4453 and JK2LB. Additionally, the effect of such an aforementioned heat treatment, here the Nb3Sn reaction heat treatment (650 degrees for 200 h) on fracture toughness of the welds is evaluated. A correlation between the evolution of properties and the quantity of secondary phases as a result of the above treatment is provided.
SN 1051-8223
YR 2018
FD 2018-02-26
LK https://hdl.handle.net/10016/35432
UL https://hdl.handle.net/10016/35432
LA eng
DS e-Archivo
RD 18 jul. 2024