With the wide application of stainless steel pipes, people's requirements for them are getting higher and higher, and the processing technology has become diversified. Pickling is one of the processing techniques. Do you know why hydrogen embrittlement occurs in stainless steel pipes after pickling?
It is because the hydrogen has the effect of peeling off the iron oxide scale when the stainless steel pipe is pickled, and it also diffuses into the steel blank matrix and then gathers at the impurities or pores, which will lead to an increase in internal stress and the plasticity of the steel. Reduced, the brittleness of steel increases, this effect is called hydrogen embrittlement. Hydrogen embrittlement is mainly affected by the diffusion speed 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 increases, the diffusion rate of hydrogen will increase sharply, but 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 there are inclusions such as hydrogen sulfide, carbon dioxide, and arsenic in the pickling process of stainless steel pipes, they will increase the diffusion rate of hydrogen atoms, which will increase the possibility of hydrogen embrittlement.