Pickling Silicon Steel: Reliable Cleaning for Carbonitriding

Summary for pickling silicon steel Discussion

Pickling steel with 2.5% silicon is the central issue in this thread: the questioner needs very clean small alloy-steel parts for uniform diffusion during carbonitriding, but vacuum-annealed parts still do not take a uniform case. They report that hydrochloric acid pickling helps, yet is not fully reliable, and suspect a stable silicon-rich surface oxide that is harder to remove than the oxide on plain carbon steel. The thread asks for experience cleaning these silicon steels for plating or other processes that require a bare-metal surface. Because the excerpt provided contains only the question and no answers, there is no named advice to summarize beyond the problem statement itself. The practical takeaway is that the user is seeking a more dependable cleaning method than HCl pickling for high-silicon steel surfaces before heat treatment.