焊接參數對超級雙相不銹鋼熔接焊道抗孔蝕影響之研究

An Investigation into the Welding Variable on the Pitting Corrosion Resistance of Super Duplex Stainless Steel Weldments

本研究以實驗量測的方式，來探討焊接參數（例如焊料進給方式及熱進給量-Heat Input）對於超級雙向不銹鋼焊道及影響區（Heat Affected Zone）之抗孔蝕能力之影響。為了在同一時間內有效控制只有一個焊接參數被改變，本研究將設計使用一半自動銲接製程模組，以完成一連串的銲道銲接。而雙相鋼焊接後之焊道及熱影響區（Heat Affected Zone），其抗孔蝕性量測方法，主要是參考ASTM G48-76、ASTM A923-94等準則及TWI（The Welding Institute）所推薦使用Ferric Chloride浸泡量測技術進行。實驗結果顯示，使用一個太高（1.8KJ/mm）或過低（1.1 KJ/mm）的熱進給量或從焊池背後搖擺進料的方式傾向降低超級雙向不銹鋼之臨界孔蝕溫度（抗孔蝕能力）。而使用一適中的熱進給量（1.4KJ/mm）及傳統焊接進料的方式（從焊池前方進料的方式）可提供超級雙向不銹鋼最佳之抗孔蝕性質。

This work was carried out to investigate the effect of welding variables, such as wire feeding technique and heat input, on the pitting corrosion resistance in the multi-pass weld and heat affected zone (HAZ) of a super duplex stainless steel. To enable control of welding variables such that one parameter can be varied at a time, a series of weldment using semi-automatic welding process were completed. The method used for pitting resistance tests was the basic ASTM G48-76 standard, with reference to the ASTM A923-94 standard and recommended practice for pitting corrosion tests for duplex stainless steel weldments by the use of ferric chloride solution from The Welding Institute (TWI). It is evident from the test results that the use of a low (1.1 kJ/mm) or an excessive high heat input (1.8kJ/mm) or oscillated filler wire entering into the back of the weld pool tends to decrease the critical pitting temperature. The best corrosion resistance was obtained when an intermediate heat input (1.4 kJ/mm, providing a suitable cooling rate) with the conventional wire feeding technique (filler wire fed into the front of weld pool) was used.