Energy-Filtered TEM Images of Sulfides in Steel

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (3) —Decrease of Copper Sulfide by Long-Time-Annealing in Ferrite Region—

“…Our prediction that Cu can diffuse very fast is inductively deduced. Interestingly, there have been some reports in the field of irradiation-induced embrittlement in material for atomic reactors, [32][33][34][35][36] which mention that Cu diffusion is about two orders of magnitude faster than Fe self-diffusion and is interpreted through Self-Interstitial-Atom (SIA) mechanism, although these experiments are carried out by using Fe-1%Cu or Fe/Cu/Fe diffusion pairs heat-treated at over 1000 C. In our opinion, these phenomena have the same origin to our reports [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and each Cu-related or Cu-S-related phenomenon is viewed from a different angle.…”

“…Our standpoint [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] and reviews of past studies have already been mentioned in details in the first report. 1) In addition, the sulfide precipitation in ferrite region in Ti-added steel has been already reviewed again in the second paper.…”

“…Therefore, it has to be made clear whether solute carbon really exists in as-hot-rolled IF steel to prove that sulfide precipitation occurs along our proposed theory. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Please note that the terminology is very confusing in this scientific field. There have been some reports to mention the correlation between age-hardening and solute carbon in ''Tistabilized Ultra Low Carbon Bake-Hardenable steel (Ti-ULC-BH)'', 25,26) whose chemical compositions are designed to be lower sulfur (<20 ppm) and/or higher Mn (>1%) to obtain BH properties so that carbon is partially and/or weakly stabilized into TiC by inhibiting the precipitation of Ti 4 C 2 S 2 .…”

Sulfide Precipitation in Titanium-Added Steel with Residual Level of Copper (1) &mdash;Precipitation in Austenite Region&mdash;

“…However, as our group has already pointed out, (2) such a trace level of Cu acts as a sulfide-former to form copper sulfide (Cu-S) in non-Ti-added steel whose sulfide-former is only Mn (more precisely, 0.01%Cu). [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] The first purpose is (#1) to extend the above concept of (2) to Ti-added steel by adding a series of our recent detailed analyses. [10][11][12][13][14][15][16][17][18][19][20] However, as in non-Ti-added steel does, (3) a residual level of Cu in Ti-added steel has been also believed to be solute in steel and there are no papers to mention the phenomenon of Cu-S precipitation induced by a tramp element of Cu.…”

“…As mentioned above, the authors have already reported the copper sulfide precipitation in non-Ti-added steel with a residual level of Cu. [3][4][5][6][7][8][9][10][11][12][13][14][15] The features are listed in Table 2.…”