What happens to the stainless steel pipe after pickling

With the wide application of stainless steel pipes, people's requirements for them are getting higher and higher, and the processing technology has also become diversified. Pickling is one of the processing techniques. Do you know why hydrogen embrittlement occurs in stainless steel tubes after pickling?

It is because the hydrogen has a peeling effect on the iron oxide scale when the stainless steel tube is pickled, and it also diffuses into the base of the steel billet and then accumulates at the impurities or pores, which will lead to an increase in internal stress and plasticity of the steel. Reduce, the brittleness of steel increases, this effect is called hydrogen embrittlement. The hydrogen embrittlement is mainly affected by the diffusion rate of hydrogen atoms.

1. The diffusion rate of hydrogen in sulfuric acid solution is much faster than that in hydrochloric acid solution.

2. If the pickling temperature is increased, the diffusion rate of hydrogen will increase sharply, and if the pickling concentration is increased, the diffusion rate of hydrogen will not increase much, so try not to pickle at low concentrations and high temperatures.

3. If the stainless steel tube has inclusions such as hydrogen sulfide, carbon dioxide, and arsenic during the pickling process, the diffusion rate of hydrogen atoms will increase, which will increase the possibility of hydrogen embrittlement.