WELDING WORK METHOD FOR STAINLESS STEEL SUPERIOR IN NITRIC ACID CORROSION RESISTANCE

摘要

PURPOSE: To obtain a welding part not degrading corrosion resistance even in an environment where stainless steel contact with a very corrosive solution such as nitric acid by determining welding conditions of base metal back surface in specific conditions for distance between the outermost layer welding metal surface and bevel bottom on base metal front surface and the amount of welding heat input. CONSTITUTION: TIG welding is performed by using stainless steel base metal containing C: 0.020wt.% or less, Si: 0.20 to 0.80wt.%, Mn: 1 to 2wt.%, Ni: 12 to 15wt.%, Cr: 16 to 18wt.%, Mo: 2 to 3wt.% and filler metal containing C: 0.020wt.% or less, Si: 0.30 to 0.65wt.%, Mn: 1.0 to 2.5wt.%, Ni: 11 to 14wt.%, Cr: 18 to 20wt.%, Mo: 2 to 3wt.%, Cu: 0.75wt.% or less. When the front surface and the back surface of the base metal are welded, the welding conditions for the back surface of the base metal should fulfill that the distance d (mm) between the outermost layer welding metal surface on the base metal front surface and the bevel bottom is 5mm or more and HI<=(d+2)/10 where HI (kJ/mm) is the amount of welding heat input.