本文探討退火爐中兩種不同材質熱交換管腐蝕破損原因。某公司退火爐有316L 及 253MA 兩種材質水平式熱交換器位於爐區頂部，因破管漏水滴落產品表面影響品質。為了 解此兩種熱交換器之腐蝕破管成因，展開原因分析。分析方法包括外觀觀察、Spark 及ICP 成分分析、截面微硬度量測、草酸電解試驗、SEM 金相分析、表面SEM厄DS 分析、腐蝕 生成物分析等。經分析結果顯示316L 熱交換器之破孔由外而內發展，外壁表面附著明顯之 氯離子，研判其破管原因應為停機冷卻後引發之孔蝕現象所造成。253MA 材質因發生敏化 現象，加上內壁沉積造成治晶腐蝕以至於穿孔滲漏。建議目前線上使用之253MA 熱交換器 應檢查有無敏化現象，或是直接更換材質。定修時應清洗熱交換器外壁與內壁，以渦電流(ET) 檢查熱交換管之缺陷狀況。冷卻水品質應加以控制，儘量避免沉積發生:操作時應防止熱 交換器發生空燒，材質更換應以含有Mo 之低碳不鏡鋼或添加Ti 、Nb之穩定化不錯鋼或鎳 基合金為主。

The pmpose of this paper is to study the failu自cause of heat exchange tubes in the annealing fumace. There are two horizontal heat exchangers made of two different materials, 316L and 253MA, located at the top of annealing furnace. The failure of the heat exchanges cause water in the tubes dropped on the product surface and affected the product surface quality. For speculating the failure cause, some investigations and studies were performed. They included appearance examination, material composition and cooling water analy帥， surface )位D analysis and SEM厄DS analysis etc. From the analysis results, it showed that the 316L tubes perforated from the outside and some chlorides were found on the surface. This implies that the failure might caused by pitting corrosion occurred in the periods of shut down. On the other hand, the leakage of the 253MA tubes was caused by the sensitization and intergranular corrosion due to the inner wall deposition. Some recommendations were proposed to avoid the failure, including sensitization examination, materials replacement, cleaning the tubes at shutdown and ET inspections, cooling water quality control, and avoid dry heating during operation.