.

Fig.3. A-C hydrogen concentration distribution in austenite phase and martensitic phase of QPT steel [55]. A 3DAPT map of a combined atom map of carbon and hydrogen of the as-charged specimen, where iso-concentration surface representing 2.5 at.% carbon is displayed in red. Carbon atoms and hydrogen atoms are represented by pink and green, respectively. The inserted map is the corresponding mass spectrum. B Atom maps of iron, manganese, silicon, carbon and hydrogen of the selected blue rectangle in A. C Average compositions of carbon and hydrogen along the marked cylinder in A. a-h: Hydrogen concentration distribution in matrix and carbides of QPT steel [6]. b, d, g are enlarged views showing carbon and hydrogen atom distribution as indicated in a, c, e; f is the carbon content along the blue cylinder in e; i average compositions of carbon and hydrogen along the blue cylinder in h. Carbon and hydrogen are represented by red and green, respectively