Assessment of Residual Stresses in ITER CS Helium Inlet Welds Fatigue Tested at Cryogenic Temperature

27th International Cryogenics Engineering Conference and International Cryogenic Materials Conference 2018

Sgobba, S.^1 ; Aviles Santillana, I.^1 ; Langeslag, S.^1 ; Fernandez Pison, P.^1^2 ; Castillo Rivero, S.^1^3 ; Libeyre, P.^4 ; Jong, C.^4 ; Everitt, D.^5 ; Freudenberg, K.^5

CERN, CH-1211, Geneve, Switzerland^1

University Carlos III of Madrid, Campus de Leganes, Av. Universidad 30, MADRID 28911, Spain^2

Escuela Tecnica Superior de Ingenieria, University of Seville, Camino de los Descubrimientos, Sevilla

41092, Spain^3

ITER Organization, Route de Vinon sur Verdon, CS 90 046-13067 St. Paul lez Durance cedex, France^4

US ITER Project Office, Oak Ridge National Laboratory, 1055 Commerce Park, Oak Ridge

TN

37831-6483, United States^5

关键词: Cable-in-conduit conductors;    Compressive residual stress;    Cryogenic temperatures;    Electromagnetic forces;    Microstructure and mechanical properties;    Structural elements;    Tungsten inert gas;    Ultrasonic shot peening;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/502/1/012095/pdf
DOI  :  10.1088/1757-899X/502/1/012095

来源: IOP

【 摘 要 】

The ITER Central Solenoid (CS) consists of six independent wound modules. The cooling of the cable-in-conduit conductor is assured by a forced flow of supercritical He at 4.5 K supplied by He inlets located at the innermost radius of the coil. The inlets consist of a racetrack-shaped boss welded to the outer conduit wall through a full penetration Tungsten Inert Gas (TIG) weld. They are critical structural elements submitted to severe cyclic stresses due to the electro-magnetic forces acting on the coils. The weld contour is shape-optimised and locally processed by Ultrasonic Shot Peening (USP), conferring large compressive residual stresses on a subsurface layer of several millimetres thickness to improve fatigue strength. The distribution of the residual stresses and the effect of USP on microstructure and mechanical properties is assessed, with reference to the results of a cryogenic fatigue test campaign, performed on peened and as-welded inlets for comparison.Published under licence by IOP Publishing Ltd.