Abstract
Explosive bonded cylinders consisting of three-layer-rings (φ800mm-L1000mm) of A286 (inner and outer rings) and Cu-Cr (damper ring) for the superconducting turbine generator were investigated.
Because of the requirement of high strength (σy=70kgf/mm2), heavy thickness (20-30mm) and multi-layers bonding, some fundamental tests were performed using the same material and thickness plates for actual structure and three-layer-rings with carbon steel and copper.
Using the knowledge from above investigations, A286/Cu-Cr/ A286 explosive bonded cylinder was manufactured and (1) diametrical change after bonding, (2) mechanical properties of A286 and Cu-Cr, (3) bonding strength and (4) fatigue strength under the severe service conditions at the event of generator short circuit were studied.
The obtained results were as follows.
(1) The diametrical changes in radial and longitudinal direction were-3.0% and 2.0% respectively.
(2) The difference of 0.2% proof stress in tangential and longitudinal direction caused by plastic strain at the bonding was remarkable.
(3) The bonding strength at two boundaries (inner-damper rings and outer-damper rings) was good enough compared with damper strength.
(4) Crushing force at the event of generator short circuit caused no separation and cracking in this structure.
