TITLE:
An Investigation on Weldability of Flared D9 Tube to Cylindrical SS316L (N) Plug Using Electro-Magnetic Compression Welding
AUTHORS:
Satendra Kumar, G. K. Dey, Archana Sharma
KEYWORDS:
Tube Flaring, Multi-Turn Coil, EM Welding, Interface Micrograph, Non-Destructive Tests, Destructive Tests
JOURNAL NAME:
Open Access Library Journal,
Vol.6 No.5,
May
27,
2019
ABSTRACT: Geometry configurations of joining partners (similar/dissimilar metals) are important to achieve effective and smooth joint in electromagnetic (EM) compression welding. Accordingly, design of welding tool (multi-turn coil) becomes challenging [1]. EM welding of flared D9 flyer tube to SS316 L (N) straight cylindrical plug has been performed under a discharge voltage of 15 - 17 kV with coil current 230 - 250 kA ataround 15.1 kHz ringing frequency. A multi-turn coil having inner diameter as flared profile identical to the geometry of flyer tube was designed along with flared Cu (annealed) driver tube. Non-destructive tests (helium leak test and X-ray tomography) and destructive tests (sectional micrographs and micro hardness test) have been conducted on welded samples to verify the interface bond formation. The transition zone at weld interface exhibits severe plastic deformation due to strain hardening with an increased hardness of around 504 VHN and a smooth wavy pattern of a maximum crest height of 40 μm. All the weld samples showed a leak rate of the order of 10-9m·bar·L/s. The present exercise of geometry modification in driver and joining metals with customized coil geometry contributed to the favorable joining conditions in EM welding.