Bulge testing of copper and niobium tubes for hydroformed RF cavities

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• 作者：H.S. Kim^a ; ^{kim.3237@osu.edu" class="auth_mail" title="E-mail the corresponding author} ; M.D. Sumption^a ; M.A. Susner^a ; ^b ; H. Lim^a ; ^c ; E.W. Collings^a
• 关键词：SRF cavities ; Hydroforming ; Tube bulge test ; FEM
• 刊名：Materials Science & Engineering A
• 出版年：2016
• 出版时间：27 January 2016
• 年：2016
• 卷：654
• 期：Complete
• 页码：13-20
• 全文大小：3822 K

文摘

The heat treatment, tensile testing, and bulge testing of Cu and Nb tubes has been carried out to gain experience for the subsequent hydroforming of Nb tube into seamless superconducting radio frequency (SRF) cavities for high energy particle acceleration. In the experimental part of the study samples removed from representative tubes were prepared for heat treatment, tensile testing, residual resistance ratio measurement, and orientation imaging electron microscopy (OIM). After being optimally heat treated Cu and Nb tubes were subjected to hydraulic bulge testing and the results analyzed. In the final part of the study finite-element models (FEM) incorporating constitutive (stress–strain) relationships analytically derived from the tensile and bulge tests, respectively, were used to replicate the bulge test. As expected, agreement was obtained between the experimental bulge parameters and the FEM model based on the bulge-derived constitutive relationship. Not so for the FEM model based on tensile-test data. It is concluded that a constitutive relationship based on bulge testing is necessary to predict a material's performance under hydraulic deformation.