Experimental studies on the performance of multilayer coated carbide tool in hard turning of high strength low alloy ste
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S. Basavarajappa Department of Studies in Mechanical Engineering, U.B.D.T. College of Engineering, Davangere 577004, Karnataka, India
V.N. Gaitonde Department of Industrial & Production Engineering, B.V.B. College of Engineering & Technology, Hubli 580031, Karnataka, India (Received 26 November 2014; accepted 17 July 2015)
The aim of the present investigation is to identify the wear mechanisms of multilayer coated carbide tool under different machining conditions during turning of hardened AISI 4340 steel. The chemical vapor deposited multilayer coated (TiN/MT TiC,N/Al2O3) carbide tool was used. The worn surfaces of the cutting tools were examined under digital optical microscope, scanning electron microscope, and elemental analysis. The investigation results showed a strong correlation between the cutting conditions and tool wear. The cutting speed and feed rate ensure the dominant effects on the tool wear followed by the depth of cut and also the progress of tool wear were verified under different intervals of time. The flank and rake faces of the cutting tool were severely gouged by the hard particles of workpiece material exhibited abrasive wear phenomenon. Intermittently, chipping at cutting edge, notching and catastrophic failure modes were observed in continuous machining.
I. INTRODUCTION
Hardened steels having hardness of above 45 HRC can be classified as difficult to machining materials. In general, the hardened steels have been conventionally machined to finished geometries by abrasive process such as grinding operation. The process recommended for the hard machining is essentially a high wear resistance cutting tool with appropriate cutting conditions in finish process.1,2 Tool wear is one of the most complex phenomenon occurs during hard machining. The tool wear leads to degrade in surface quality (white layer formation) and increases tensile residual stresses on the machined surface.2,3 The cutting tool life must be carefully observed in the turning of hard materials, since it is a finishing process requiring better surface finish comparable to grinding operation. The tool wear in hard turning is influenced by various parameters, such as cutting conditions, workpiece hardness, tool material and interaction of tool-workpiece, and so on. Generally, the cutting tool performance is limited by flank wear, nose wear, crater wear, edge chippings, or combination of
Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.236 3056
J. Mater. Res., Vol. 30, No. 20, Oct 28, 2015
http://journals.cambridge.org
Downloaded: 01 May 2016
these. The tool wear either occurs gradually by adhesive or abrasive wear, through plastic deformation, and discrete fracture mechanism, or by combination of these.2,3 The occurrence of each wear mechanism depends on high thermal, mechanical, and chemical loads generated in hard machining. Carbide cutting tools are the regular tools for machining of alloy steels and cast iron. These cutting tools have a high de
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