热输入对S32750超级双相不锈钢TIG焊接接头腐蚀性能的影响

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

使用自熔TIG对1. 2 mm厚度的S32750冷轧薄板进行了焊接,对焊接接头进行了N含量和铁素体含量的检测、金相组织和析出相的分析、临界点蚀点位和点蚀率测量的试验,分析了不同焊接热输入对焊接接头腐蚀性能的影响。结果表明,在100～140 J/mm的焊接热输入条件下,点蚀性能均略低于母材,但符合S32750的标准要求。对于降低S32750焊接接头耐点蚀性能的原因,一是由于低焊接热输入导致了HAZ的Cr_2N析出,造成周围区域贫铬;二是由于高焊接热输入导致了焊缝铁素体微区的PREN较低。

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 Cr 2N in HAZ and the chromium depleted region,the other is that high welding heat input reduces the PREN in the weld ferrite.