Modification of Nonmetallic Inclusions by Ti and La Complex Treatment in High‐Al Transformation‐Induced Plasticity Steel

Abstract

The effect of Ti and La complex treatment on the formation and evolution of inclusions in high-Al transformation-induced plasticity steel is investigated by laboratory experiments and thermodynamic calculations, with consideration given to the amount of La added and the sequence of the addition of Ti. The main inclusions are Al 2 O 3 and AlN inclusions before the Ti and La additions. The AlN inclusions are transformed into TiN inclusions with the addition of 0.1 wt% Ti. After the subsequent addition of 0.007 wt% La, the main inclusions are LaAlO 3 , La 2 O 2 S, and TiN. With the addition of 0.06 wt% La to molten steel, the main inclusions are La 2 O 2 S, La 2 S 3 , and TiN. La may prevent the precipitation of TiN inclusions. Different addition sequences of Ti and La result in the same types of inclusions, with higher La addition. In the case of La addition before Ti, Ti can restrain the formation of La-containing inclusions, and the number density of inclusions increases.

Effect of Yttrium Addition on Nonmetallic Inclusions in FeCrAl Alloys

“…The interaction coefficients required are shown in Table 2 . [ 3,23–28 ] …”

“…=–0.001, [ 3 ] =–107 + 275 000/ T , [ 28 ] =47.4 [ 28 ]…”

“….41 [29] 0.03 [29] Al 0.025 0.045 0.03 0.033 [3] -6.6 r Al O =0.012, [25] r Al;O O =327 300/T þ 127 [26] r Al Al =-0.001, [3] r O Al =-107 þ 275 000/T, [28] r O;Al Al =47.4 [28] Figure…”

“…However, most of these inclusions are found as REAlO 3 rather than rare earth oxides in the literature. [20,21,28,31] Because the properties of rare earth elements are similar, it is assumed that YAlO 3 inclusions exist in accordance with the existence of LaAlO 3 and CeAlO 3 , even though the existence of YAlO 3 inclusions is not directly specified.…”

“…The modification of inclusions in FeCrAl alloys by rare earth Y was investigated by taking alloy samples at different times in O -0.032 [24] -0.286 [25] -0.133 0.057 [26] -0.2 -6.12 [27] S -0.011 0.035 -0.028 0.01 [28] -0.27 -0.55…”