PURPOSE: To fine the coarse granular region of build-up part and prevent hydrogen brittleness by performing build-up welding of the groove faces by the filler metal of the specific components, thence performing regular welding.
CONSTITUTION: Prior to regular welding, the groove faces are subjected to build- up welding by using the pure iron or the filler material containing one or two or more kinds of chromium; 5% or less, molybdenum; 1% or less, titanium; 0.3% or less, niobium; 0.5% or less based on weight as carbide forming elements stable against hydrogen erosion, to thicknesses 2W6mm. Next, in the regular welding, the welding is so executed that the foregoing build-up metal 1 remains 1W4mm. Further the regular welding final layer 2 is welded in accordance with build-up procedure. As a reason for limiting these, the upper limit of the components, with regards to the components, is limited to achieve the improvement of toughness and weldability. With regards to thickness, the lower limit is determined to ease welding procedure and the upper limit is determined in order to let the heat affection at the regular welding reach the coarse crystal part.
KIRIHARA SEISHIN
MATSUZAKA KIYOU
IKEDA SHINZOU
