Influence of heat input on corrosion property of TIG welded S32750 super duplex stainless steel joints

The influence of heat input on the corrosion of the TIG-welded weld S32750 type super duplex stainless steel joints was investigated. The N content,ferrite phase content,microstructure,precipitated phase,CPT and pitting were measured and observed,respectively. The results show that at the heat input in 100 ～ 140 J/mm,the pitting corrosion resistance of welded joints are slightly lower than that of base metal,and in accordance with the standard of S32750. The reasons to reduce the pitting corrosion resistance of S32750 welded joints are two aspects.One is that low welding heat input results in the precipitation of Cr₂N in HAZ and the chromium depleted region,the other is that high welding heat input reduces the PREN in the weld ferrite.