The Effect of Different Non-Metallic Inclusions on the Machinability of Steels

Abstract

Considerable research has been conducted over recent decades on the role of non-metallic inclusions and their link to the machinability of different steels. The present work reviews the mechanisms of steel fractures during different mechanical machining operations and the behavior of various non-metallic inclusions in a cutting zone. More specifically, the effects of composition, size, number and morphology of inclusions on machinability factors (such as cutting tool wear, power consumption, etc.) are discussed and summarized. Finally, some methods for modification of non-metallic inclusions in the liquid steel are considered to obtain a desired balance between mechanical properties and machinability of various steel grades.

Influence of inclusion type on the very high cycle fatigue properties of 18Ni maraging steel

“…-6 K -1 [41] and 9.4 9 10 -6 K -1 for TiN [42], whereas the thermal expansion coefficient of maraging steels, a m , is about 10 9 10 -6 K -1 . The relatively higher coefficient of thermal expansion of maraging steels leads to higher contraction during cooling of the material, inducing compressive residual stresses in the inclusion.…”

Modification of the inclusions in austenitic stainless steel by adding tellurium and zirconium

“…It should be pointed out that the total effect of different inclusions on the machinability and final mechanical properties depends on such characteristics of non-metallic inclusions as chemical composition, hardness, deformability, number, size, morphology and distribution in steel. 8 The existence of MnS particles elongated during forging and hot-rolling in plastic mould steels is a cause of increasing the anisotropy of mechanical properties. The control of MnS particles with the additions of Ti, Cr, Zr, etc.…”

Thermodynamic Property of Tellurium in Molten Iron Measured by the Transpiration Method

“…Shun UEDA, 1) * Shumpei SUZUKI, 1) Takeshi YOSHIKAWA 2) and Kazuki MORITA 1) 1) Department of Materials Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan.…”

“…Resulfurized free machining steel contains dispersed globular MnS inclusions, which contribute to its high machinability by inducing additional stress around these inclusions and promoting crack formation during machining processes. 1) Those inclusions, however, are severely elongated during the hot-rolling process and result in anisotropic mechanical properties of the steel. Tellurium is added in order to overcome this problem.…”