From the study of the dephosphorization of liquid iron by CaO-FeO-SiO₂ slag and that containing Na₂O up to 22wt%, the effect of Na₂O on the phosphorus distribution between liquid iron and CaO-MgO-Fe_tO-SiO₂ slag has been investigated. The effect is evaluated as a CaO-equivalence, and the following equations are obtained. (i) log{(%P)/[%P]}=0.071{(%CaO)+0.1(%MgO) +[1.5(%Na₂O)+4.4]}+2.5log(%T.Fe) +8260/T-8.56 [1<(%Na₂O)<20] (ii) log[(%P₂O₅)/{[%P]²(%Fe_tO)⁵}]=8.90log{(%CaO) +0.3(%MgO)+[1.6(%Na₂O)+5.0]} +18100/T-27.49 [1<(%Na₂O)<20]
The effect of Na₂O on the activity coefficients of P₂O₅ and Fe_tO are also analyzed on the mole fraction base. The activity coefficient of P₂O₅ is expressed as follows: logγ_P2O5=-1.01{15N_CaO+7N_MgO+5N_FetO +27N_Na2O-1N_Si2O-7N_P2O5}-7.55
The relationship between the phosphate capacity and the theoretical optical basicity for slaps with and without Na₂O addition is determined and some discussions are made.

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Some statistical functions which deal with the joint statistical properties of two data records are employed to develop a new method for quantitative evaluation of the joint segregation characteristics of two alloying elements. An index showing the extent to which the two elements segregate at positions close to each other or in the form of a compound is proposed. The proposed method and the index are used to quantify the effect of calcium treatment on the segregation of MnS in four commercial steel slabs, continuously cast under different operating conditions, in long and short spacing ranges. Combination of sulfur with calcium in preference to manganese and phosphorus in a calcium treated slab is quantitatively verified. The reliability and the reproducibility of the results are confirmed.

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Model studies have been made on the rate of mass transfer between molten slag and metal with gas injection stirring. A Li₂O-SiO₂Al₂O₃ slag-molten Cu reaction system for Si oxidation has been selected as the model reaction system. The explored reaction is oxidation of Si by FeO, taking place under the condition of rate-controlling by Si transport in the metal phase. Kinetic experiments were done at 1250°C. The slag-metal bath was stirred by Ar gas injected through a nozzle located at the crucible bottom. The apparent metal-side mass transfer coefficients of Si, k'_Si, are calculated from the rate data. Relations between k'_Si and experimental conditions (gas flow rate, V_g; metal depth, h_M; crucible diameter, d_c) have been investigated.
It is found that the dependence of k'_Si on the gas flow rate varies at certain gas flow rates denoted by V^*_g and V^**_g. In the low V_g range (V_g<V^*_g), k'_Si is proportional to (V_g/d²_c). In the medium V_g range (V^*_g<V_g< V^**_g), k'_Si increases only slightly with increasing V_g. In the high V_g range (V_g>V^**_g), the extent of the increase in k'_Si with V_g increases again. It is also found that k'_Si increases with metal depth, h_M, below a transitional depth h^*_M. When h_M>h^*_M, k'_Si becomes independent of h_M.

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An analytical study has been made on the metal side mass transfer in a slag-metal reaction system with gas injection stirring. Considerations have been given of the relation between metal side mass transfer and the fluid flow in the vicinity of the slag-metal interface. On the basis of a theory of turbulent phenomena, metal-side mass transfer coefficients are derived as functions of gas injection stirring conditions. The theoretical equations are rearranged to dimensionless correlation equations.
The mass transfer data obtained by the authors from model studies for molten slag-Cu reaction system of Si oxidation at 1250°C and the available results of model studies at low temperature (aqueous solution-amalgam system at room temperature and molten salt-molten Pb system at 450°C) are correlated successfully by the equations obtained in the present study. It is found that the dimensionless correlation equations obtained in the present study are applicable to the data of ladle desulfurization.

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High-grade bent pipes with heavy-wall (1.25 in. for API-5LX65 and 1.61 in, for API-5LX60) were produced by induction hot bending process for use in Arctic regions. Niobium and vanadium-added steel pipe, which is commonly used in the pipe line industry, was examined in this paper for both trial and production bending.
The characteristics of the induction hot bending process and the properties of the bent pipe were investigated. By a combination of suitable bending temperature, proper chemical composition of weld metal and tempering after bending, good Charpy impact properties at -46°C and satisfactory CTOD value at -10°C were obtained. Tensile strength at bent, boundary and tangent portions was almost uniform longitudinally and circumferentially.

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Effects of MC and M₂₃C₆ carbides on the creep rupture strength of 18%Cr-10%Ni-Ti-Nb stainless steel were quantitatively evaluated. The solubility relationship for (Ti, Nb) C was determined, as creep rupture strength depends on the amount of carbon dissolved during solution treatment. On one heat, the solution treatments at various temperature were conducted and the quantitative relationship between MC carbide and creep rupture strength was obtained by carrying out creep rupture tests at 650°C. On the basis of this result, the effect of M₂₃C₆ carbide on the creep rupture strength was calculated by deducting the contribution of MC carbide from the practical rupture strength. The following formula was obtained for estimating the rupture strength of this steel. (650°C, 10000h creep rupture strength) =21.5×(C as MC)+6×(C as M₂₃C₆)+8.5(kgf/mm²)

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In order to elucidate the formation of Goss grains after transverse cold rolling in a grain oriented silicon steel, computer color mapping was performed by using orientation information of Kossel diffraction patterns taken in advance in the recrystallized grains.
For computer color mapping in the vicinity of the steel surface after first stage cold rolling in the transverse direction and the subsequent intermediate annealing, the formation of Goss grains is very scarce and the size of these primary grains is much larger than that after a first straight cold rolling. Also, for similar computer color mappings after a second stage cold rolling in the transverse direction and the subsequent decarburization and primary recrystallization annealing, the formation of Goss grains is strongly inhibited. This inhibition has a decisive influence in conjunction with the cold rolling directions in the first and second stages; the previously generated Goss grains disappear by the transverse cold rolling. The preferential formation and inheritance of the celebrated Goss nuclei, which can be inherited by the structure memory from the original hot rolled silicon steel, are considered to be accomplished in cold rolling parallel to the hot rolling direction.

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