Comparison of Sensitization of Explosively Bonded and of Welded Stainless Steel Plugs

Abstract

Plug bonding method was often applied to prevent accidents of failure in heat exchangers. In these cases, the plug bonded region would be subjected to low temperature sensitization in the service period.
Then the susceptibility to low temperature sensitization of explosively bonded and welded plugs was compared. The main results are as follows. In case of welded plugs, corriosion attack was concentrated to grain boundaries in HAZ by Strauss test. On the otherhand, the susceptibility to low temperature sensitization of the explosively bonded plugs was comparatively higher than expected, because of carbide precipitation occuring spontaneously with the disappearance of martensite. And corrosion had propagated along prior martensite lath where many carbide particles had precipitated.