The Effect of Tellurium on Properties of Steels

Steels containing Te are generally used for free cutting steels. But the effect of Te on mechanical properties and mechanism of grain growth retardation by Te are not well knownyet. The authors have studied the influence of Te on impact properties, tensile properties and austenite grain size of common structural steels at various temperatures. Tellurium compounds were identified by X-ray diffraction with electrolytically extracted residues and by analysis of the compounds using electron probe X-ray microanalyzer. The state of dispersion of telluride was examined by autoradiography using 125m Te isotope. The obtained results are as follows. (1) Addition of Te to the steels lowered remarkably the transition temperature in Charpy impact test and increased yield point. (2) Te raised coarsening temperature of austenite grain and in the case of the combined addition of Te and such grain refining element as Al, Nb or Ti, the coarsening temperature was such higher than that in the case of the separate addition of Al, Nb or Ti. (3) Tellurium compounds were identified to be FeTe and MnTe and it was found by autoradiography using RI Te that they dispersed uniformly in the matrix.