Assessment of Critical Hydrogen Concentration in As-Cast and Hot-Rolled Billets in Medium Carbon Steels

The presence of hydrogen severely affects the mechanical properties of semi-manufactured and final steel products. Such presence is affected by different factors which show up throughout the whole manufacturing process and varies during the different stages according to both product features and various process parameters. This article presents an experimental methodology to assess the critical hydrogen concentration in as-cast and hot-rolled billets in medium carbon steels, which allows highlighting their robustness to hydrogen embrittlement. Such approach is based on a combination of hydrogen-induced cracking and slow strain rate tensile tests, which are conducted on both as-cast and hot-rolled billets samples. The experiments highlight that the hydrogen presence is more critical on the as-cast semi-products than on the hot-rolled billets, which show a higher robustness, as they can tolerate higher values of hydrogen content.