Analysis of proficiency testing results of metallographic method for determination of α-phase area content in duplex stainless steel and comparison of different etching methods in standard
LI Zhao1, LI Jikang2, DU Min2, GUO Li2
1. China NIL Research Center for Proficiency Testing, Beijing 100081, China; 2. Central Laboratory, Central Iron and Steel Research Institute, Beijing 100081, China
Abstract：In view of the proficiency test project of α-phase area content determination of duplex stainless steel carried out in our company in recent 3 years, it was found that the detection results were affected by the etching method through the analysis of unsatisfactory results in proficiency testing. Sample A (belt duplex steel) and sample B (mesh duplex steel) were employed. Four kinds of chemical etching methods in GB/T 13305-2008, including hot or boiling alkaline potassium ferricyanide solution, copper sulfate-hydrochloric acid solution, ferric chloride-hydrochloric acid-ethanol solution, and electrolytic corrosion (oxalic acid aqueous solution, KOH or NaOH aqueous solution), were compared. It was found that the α-phase was white when heated to 600 ℃ in the furnace after being corroded by ferric chloride-hydrochloric acid-ethanol solution, which was not in accordance with the standard that the α-phase produced by this method was reddish brown. Therefore, the alkaline potassium ferricyanide solution and KOH or NaOH electrolytic corrosion were preferred and recommended.
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LI Zhao, LI Jikang, DU Min, GUO Li. Analysis of proficiency testing results of metallographic method for determination of α-phase area content in duplex stainless steel and comparison of different etching methods in standard. , 2021, 41(2): 78-82.
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