Titanium (Ti)        Final deoxidizer, the deoxidizing power is not as good as Al and Zr, but stronger than Si and Mn. It is usually used as an additional deoxidizer when controlling the amount of Al and N.

1. Advantages
   A. It can form stable carbides and nitrides, so it can reduce the grain boundary corrosion of stainless steel (similar to the effect of Nb) and the grain boundary sugar crystal breakage (AlN) of general steel (similar to the effect of Zr);
   B. It controls nitrogen pores with good effect and also has a grain refinement effect;
   C. The deoxidation product is TiO2, with a melting point of 1855℃, and its effect on the fluidity of molten steel is lower than that of Al2O3.
2. Disadvantages
   A. The action time is short (about 30s), and the brittleness of TiC is prone to occur when the residual amount is above 0.05%;
   B. When making high-titanium steel with wet sand molds, it will promote the occurrence of pinholes.

Rare earth elements
The effect is similar to that of silicon-calcium alloys (i.e. dense cerium alloy, cerium-lanthanum, etc.).

1. Advantages

A. These elements have a composite effect, which can form stable oxides and nitrides, sulfides, and hydrides to a certain extent;

B. It can improve the red-hot brittleness of high-alloy steel, and also has the effect of grain refinement and inclusion spheroidization;

C. In high-alloy steel or stainless steel, it can improve elongation and increase strength (high temperature strength is also helpful), and it is also helpful for corrosion resistance;

D. Lower the liquidus line, and if used properly, it helps fluidity;

E. Reduce the segregation of phosphorus at the grain boundary;

F. Increase the number of dendrites and shorten the length, thereby refining the grains;

G. Inhibit temper brittleness;

H. Reduce the sensitivity of "HIC (hydrogen induced cracking)" (one of the causes of welding cracks), and it is also effective in resisting "hydrogen sulfide stress-sensitive cracking" (a common problem in petrochemical industry, stainless steel, and heat-resistant steel castings).

2. Disadvantages
A. When added in excessive amounts, coarse inclusions will be formed, affecting the fluidity of molten steel and the mechanical properties of castings (La2O3 melting point 2327℃);
B. Short action time (about 30 seconds);
C. When added in excessive amounts, it will react with the furnace lining and produce a large number of inclusions.
D. Usually added to the ladle, the addition amount is about 0.02%, mostly used in combination with other deoxidizers, rarely used alone. The most appropriate amount is three times the sulfur content to spheroidize the inclusions.

Selenium (Se)

Generally used as an additive to prevent pore formation.

1. Advantages

A. It will not cause red hot brittleness in steel;

B. It can inhibit pore formation and increase the fluidity of molten steel by reducing the surface tension of molten steel;

C. It has a deoxidizing effect and can increase the toughness of steel;

D. ​​For high chromium steel castings, 0.01~0.02% selenium can be added to prevent pores;

E. In austenitic chromium-nickel stainless steel, the addition can be controlled between 0.0125~0.1%.

2. Timing of addition:
   A. When added in the form of ferroselenium, in the ladle;

B. Add in the liquid flow in the elemental state.

Tellurium (Te) The effect of tellurium is similar to that of selenium.
The differences are:

1. Non-toxic;

2. Nickel telluride will form in high-nickel steels, causing red-hot brittleness (that is, when used at high temperatures, low-melting-point nickel telluride will form at the grain boundaries, causing the casting to crack).