Effect of Mg–Ti Deoxidation on the Formation Behavior of Equiaxed Crystals During Rapid Solidification of Iron Alloys

Abstract

The effect of Mg-Ti deoxidation on the solidification structure of advanced high strength steel was investigated by observing the solidification structure and also the inclusion particles. The effect of precipitation of TiN, MgO, and "TiN-MgO" hybrid inclusion on the formation of fine equiaxed crystals was evaluated. The composition of inclusions was observed to change in the order of MgO ! "MgO(core) þ TiN(surface)" ! Ti 2 O 3 by reaction time, which corresponded to the change of solidification structure as "columnar ! equiaxed ! columnar." This could be understood from the concept of lattice disregistry in between delta iron and MgO (3.97%), TiN (3.91%), and Ti 2 O 3 (18.9%). However, even with very low disregistry between delta iron and MgO, the MgO itself did not work as an effective catalyst, indicating that there is another criterion for determining a good catalyst. The mechanism of the formation of TiN on MgO surface was schematically described. The precipitation of TiN on MgO surface was feasible although the content of Ti and N was lower than the equilibrium solubility product for the formation of TiN. Because disregistry between TiN and MgO is very low (0.05%), the precipitation of TiN on the surface of MgO is energetically more favorable.

Influence of Refractory-Steel Interfacial Reaction on the Formation Behavior of Inclusions in Ce-containing Stainless Steel

“…The detailed information for the inclusion characterization using EEM in conjunction with FESEM-EDS is reported in our previous article. [23][24][25][26] For simplicity, a metal sample (0.4 to 0.5 g) was dissolved in 10% AA (10% Acetylacetone -1% Tetramethylammonium chloride -Methanol) solution under a total electric charge ranging from 4 000 to 5 000 coulombs (500 mA current, from 2 to 3 hours). The electrolyte solution was vacuum-filtered using a membrane filter with an open pore size of 0.2 μm.…”

“…slag-steelinclusion-refractory systems using this package has been successful in various kinds of applications. 14,[22][23][24][25][26][29][30][31][32][33][34] The 'FToxid' and 'FTmisc' databases were selected for estimating the oxide and molten steel phases. The computed results are shown in Fig.…”

Formation of Inclusions in Ti-Stabilized 17Cr Austenitic Stainless Steel

“…This is also confirmed by the results obtained from other studies. [27][28][29] Figure 9 shows the changes in composition of complex inclusions for promoting the heterogeneous nucleation of TiN as a function of time. After Ti addition, reaction between [Ti] and [O] can happen according to Eq.…”

Precipitation Behavior of Primary Precipitates in Ti-microalloyed H13 Tool Steel

“…[6][7][8] The selection and control of particle size is important to the utilization efficiency of titanium. However, large precipitates can be always found in the Ti-containing steels.…”