With the widespread use of stainless steel pipes, the requirements for them are becoming increasingly stringent, and processing techniques are becoming more diversified. Pickling is one such process. Do you know why pickled stainless steel pipes experience hydrogen embrittlement?
This is because during pickling, hydrogen gas has a peeling effect on the iron oxide scale and diffuses into the steel substrate, accumulating at impurities or pores. This leads to increased internal stress, reduced plasticity, and increased brittleness—a phenomenon known as hydrogen embrittlement. Hydrogen embrittlement is primarily affected by the diffusion rate of hydrogen atoms.
1. Hydrogen diffuses much faster in sulfuric acid solution than in hydrochloric acid solution.
2. Increasing the pickling temperature dramatically increases the hydrogen diffusion rate, while increasing the pickling concentration does not significantly increase it. Therefore, avoid pickling at low concentrations and high temperatures.
3. If there are inclusions such as hydrogen sulfide, carbon dioxide, and arsenic in the pickling process of stainless steel pipes, the diffusion rate of hydrogen atoms will be increased, which will increase the possibility of hydrogen embrittlement.
Post time: Dec-05-2025