Non-metallic inclusions in steel in relation with the formation of deposited layers PVD coated HSS tools
Non-metallic deposits on the rake face of high speed steel (HSS) tools have a considerable effect on tool life. It is known that for carbide cutting tools used to machine steels, deposited layers containing aluminium, silicon and calcium are a key factor in increasing tool life and cutting speeds. However, the existence of alumina has detrimental effects on tool life.
The conditions required for the formation of these layers is, however, poorly understood.
In a paper published in AZojomo* by T. L. Banh, Q. T. Phan and D. B. Nguyen from Thai Nguyen University of Technology, the authors examine the conditions for the formation of the deposited layers on the rake face of Physical Vapour Deposited Titanium Nitride (PVD-TiN) coated HSS cutting tools. These conditions were then correlated to tool wear.
It is evident from this study that the chemical composition of the inclusions in the steels does not play an important role in the formation of the layers. However, the existence of silicate inclusions in steel, especially their sizes and shapes, has a direct influence on layer formation. The existence of the silicate inclusions eliminates a built-up edge (BUE) on the cutting edge and may be involved with the formation of the white layer in the crater wear, leading to a reduction in tool wear.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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