Hydrogen trapping sites in high-strength steels hardened by cold drawing (PC Wire) and heat treatment (PC Bar) were investigated using thermal desorption spectroscopy (TDS) and secondary ion mass spectrometry (SIMS). Both steels were stressed and dipped in 20% NH_4SCN solution at 323K to occlude hydrogen for TDS analysis, whereas they were stressed and dipped in D_20 and 20% NH_4SCN solution at 323K to occlude deuterium for SIMS analysis. TDS analysis shows that PC Wire occludes hydrogen at the peaks of 470 K and 630 K, whereas PC Bar mainly occludes hydrogen at 470 K and slightly at 630 K. SIMS analysis makes it possible to observe the trapping sites of deuterium instead of hydrogen in high-strength steels. PC Wire traps deuterium along the drawing direction. PC Bar traps deuterium at the grain boundaries and on the inclusions. The correspondence between TDS and SIMS shows that hydrogen at 470 K is evolved from the matrix that includes dislocations and grain boundaries. In contrast, hydrogen at 630 K is evolved from inclusions and segregation of P.
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