Tellurium Treatment for the Modification of Sulfide Inclusions and Corresponding Industrial Applications in Special Steels: A Review

Abstract

In 1782, Franz-Joseph Müller von Richenstein, a chemist, discovered a rare element with properties similar to those of selenium (Se). In 1798, Martin H. Klaproth, a German chemist, rediscovered this semi-metallic substance and named it tellurium (Te). [1] Te is mainly concentrated in scattered telluride minerals, sulfide mineral structure of most gold deposits, and bismuth tailings. However, in nature, Te appears in quantities that are considered negligible [2] and is mainly extracted from the ore. Generally, concentrations of 1% to 4% Te can be recovered from the anode slime of an electrolytic copper (Cu) refinery. [3] It has been reported that seafloor ferromanganese nodules are rich in Te; however, the recovery of seafloor minerals is still in its infancy. [3] In organic chemistry, Te can also be produced by the reaction of organic matter with metal compounds of Te. [4] Te plays an important role in chemicals, electronics, inorganic nonmetallic materials, metallurgy, and other industries. [5][6][7][8] Tellurides are considered excellent materials for thermoelectric technologies. [9][10][11][12][13] Te is also widely used nonferrous metallurgy and iron and steel metallurgy. Te can significantly improve the properties of Cu-, tin (Sn)-, and lead (Pb)-based alloys, steels, and cast irons. In the iron and steel metallurgical industry, Te is usually utilized as an added element in steels to refine the grains, regulate the morphology and occurrence state of sulfides in steels, and improve the mechanical properties of steels. [14,15] Te is widely used to increase the machinability of steels. Therefore, Te-bearing steel is typically used to manufacture parts with high precision, high surface quality, and rapid cutting. The forms of Te in different type of steel vary. In addition to the usual states of Fe 1.2 Te and MnTe, [16,17] PbTe [18] is formed in Pb-alloyed steels; Cr 2 Te 3 , [19,20] stainless steels; and CuTe, Cu-alloyed steels. [21] In addition, composite particles formed by telluride and sulfide have been reported in Te-treated sulfur (S)-bearing steel. [22][23][24] In recent years, Te has been added to S-bearing steels, such as free-cutting steel and medium-carbon microalloyed steel, also called nonquenched and tempered steel (NQTS) in China, to reduce the aspect ratio of sulfide and the anisotropy of steel. [23,24]

Modification of MnS inclusion with trace tellurium to improve the machinability of medium-carbon low-sulfur steel

“…At the same time, [ pct Te ]/[ pct S ] affects the forms of telluride in steel, under the condition of high [ pct Te ]/[ pct S ], telluride is composite MnTe-MnS, while divorced eutectic MnTe-MnS forms when [ pct Te ]/[ pct S ] is low. According to the MnTe-MnS binary phase diagram, MnTe-MnS is likely to be Mn(Te,S) due to the solid solubility between MnTe and MnS [14,15].…”