| 摘要 |
PURPOSE: To provide a nitric hydrofluoric acid pickling method capable of setting the most suitable pickling condition in response to different kinds of stainless steel different in chemical compositions. CONSTITUTION: In this pickling method of the stainless steel, the steel is pickled so that a value W of the following equation defined by the temp. of the bath, hydrofluoric acid concn. in the bath and pickling time is in a range of -1<=W<=1 when using a nitric hydrofluoric acid bath containing 3-30% nitric acid and hydrofluoric acid. W=5.8-0.3×(Cr%+Mo%)-(T-50)/20}+log(C/2)+ log(t/10). Cr% is chromium content (wt.%) in the stainless steel. Mo% is molybdenum content (wt.%) in the stainless steel, T is the temp. ( deg.C) of the nitric hydrofluoric acid bath, C is the concn. (wt.%) of the hydrofluoric acid in the nitric hydrofluoric acid bath and (t) is pickling time (min). In this way, a stainless steel product having a surface texture uniform and moderate in surface roughness, and with brightness or whiteness in surely produced.
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