Hydrogen analysis in steels

Dosing hydrogen in steel is not an easy task. It involves dosing very small quantities of this element (from 0.1 to a few micrograms per gram of steel) in a matrix which does not retain it easily, and which may even react with it to some extent.

Hydrogen will exist in many forms in steel. These forms may or may not be in mutual equilibrium, mobile or immobile.

Moreover, there are countless sources of contamination or pollution of samples, whether mineral (water vapour, hydroxides, etc.) or organic (grease, etc.).

Today's answers to these problems of qualitative and quantitative determination of hydrogen in steel can be divided into three parts:

• sampling: what are the different types of sampling available and, above all, how do you obtain a "good sample"?

• dosing: what different techniques can be used to measure the exact quantity of hydrogen present in the sample?

• critical dosing: how can we be sure that everything has gone smoothly, and how much faith should we place in the values obtained?