The Effect of Tellurium on the Formation of MnTe-MnS Composite Inclusions in Non-Quenched and Tempered Steel

Ping Shen,Qiankun Yang,Shufeng Yang,Dong Zhang,Jianxun Fu

doi:10.3390/met8080639

Ping Shen, Qiankun Yang + Show 3 more

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https://doi.org/10.3390/met8080639

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Abstract

Te is a seldom-used alloying element, which is mainly used in free-machining steel. The Te content in this kind of steel is relatively low, and only a small amount of MnTe is generated. In previous studies, the effect of Te on the formation of inclusions was not fully studied. In order to clarify the mechanism, different amounts of tellurium were added into 38MnVS6 steel to form a certain amount of MnTe. The MnTe wrapped the MnS, forming a composite inclusion. With the increase of Te content in the steel, the diameter of inclusion increased, while the aspect ratio of inclusion varied little. The aspect ratio of most inclusions was in the range of 1~3. Besides, the MnS in the MnTe-MnS composite inclusions gradually changed from one big particle to several small particles. The solidification of the steel, as well as the precipitation of MnS and MnTe, was the main factor that affecting the formation of the composite inclusion. The mechanism of the process was systematically expressed in the current study.

Highlights

In some resulfurized steels, Te has been used as an additive to improve the machinability of steel [1,2,3]
A small amount of Te can significantly reduce the aspect ratio of MnS inclusion, leading to the globularization of MnS inclusion, which remarkably improves the machinability of the steel, and prevents the anisotropy of the steel property [4,5,6]
Te contents captured captured with an optical microscope

Summary

Introduction

Te has been used as an additive to improve the machinability of steel [1,2,3]. A small amount of Te can significantly reduce the aspect ratio of MnS inclusion, leading to the globularization of MnS inclusion, which remarkably improves the machinability of the steel, and prevents the anisotropy of the steel property [4,5,6]. Te is the key alloying element for the production of ultra-free machining steel. The solubility of Te in steel is very small [7,8], even at 833 ◦ C and the solubility of Te in α-Fe is only 1.5 at % [9]. According to the Te content added into the steel, Te may dissolve into

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Discussion

Conclusion