[en] The aim is to show how the high alloy steel manufacturers in France attempted to meet increasing demand by the electronuclear industries by the design and development at moderate cost and within a rather short period, of high level products intended to meet specific requirements. In this prospect, the qualitative and quantitative requirements are determined, the evolutions of the working methods connected to the design and manufacture of steel products are analysed. The economic implications which resulted and a few examples of the manufacture of particularly well suited products are evoked