PURPOSE: To prevent the corrosion in a weld heat affected zone by masking the weld heat affected zone in the state vulnerable to corrosion owing to deposition of intergranular carbide after welding with a rubber-like material having sealing property.
CONSTITUTION: Rubber is touched and fixed to the above-described weld heat affected zone of a welded iron alloy structure of a tank, pump, etc. more particularly a welded stainless steel structure used under highly corrosive environment such as sea water environment. The rubber is formed adding 5W350wt% pulverous powder of zinc having 1W500μ grain size and 20W100wt% MgO to a rubber base material provided with conductivity by dispersing fine carbon particles therein. When the rubber material contacts with the weld heat affected zone the surface thereof is fully polarized to cathode, and the fine zinc particles in the rubber material causes anodic dissolution. The intersticial liquid is maintained weakly alkaline by such dissolution and the passivation film on the surface of the interstitial metal is stabilized and therefore the corrosion of the weld heat affected zone is prevented.
SHIMIZU TASUKU
OZAKI TOSHINORI
SAKATA HIROSHI
NAGASAWA SHIGENOBU
