Surface alloying of H11 die steel by tungsten using EDM process

The objective of this study is to investigate the phenomenon of surface alloying by electrical discharge machining (EDM) process using tool electrodes manufactured by powder metallurgy (PM) process. Efforts have been made to find out the machining conditions that facilitate the transfer of desirable...

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Bibliographic Details
Published in:International journal of advanced manufacturing technology 2015-06, Vol.78 (9-12), p.1585-1593
Main Authors: Gill, Amoljit Singh, Kumar, Sanjeev
Format: Article
Language:English
Subjects:
Alloying elements
CAE) and Design
Carbon
Cemented carbides
Cementite
Computer-Aided Engineering (CAD
Die steels
Dies
EDM electrodes
Electric discharge machining
Engineering
Free surfaces
Industrial and Production Engineering
Iron carbides
Mechanical Engineering
Media Management
Microhardness
Migration
Order parameters
Original Article
Orthogonal arrays
Powder metallurgy
Process parameters
Product design
Scanning electron microscopy
Surface alloying
Surface finish
Surface properties
Surface roughness
Taguchi methods
Tungsten carbide
Variance analysis
X-ray diffraction
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Summary:The objective of this study is to investigate the phenomenon of surface alloying by electrical discharge machining (EDM) process using tool electrodes manufactured by powder metallurgy (PM) process. Efforts have been made to find out the machining conditions that facilitate the transfer of desirable alloying elements (tungsten and carbon) to the machined surface. The quality of the machined surface is the key issue while surface alloying in EDM process. The Taguchi method and L18 orthogonal array are used to find the best level of process parameters in order to achieve the high surface finish and microhardness. Experiments are conducted on hot die steel H11 using electrode (copper-tungsten) manufactured by PM process. Six input parameters are considered, and their significance is investigated by analysis of variance (ANOVA). Different techniques like scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) have been used to ascertain the characteristics of the machined surface. Results show improvement in microhardness of the alloyed surface by 83 %. Surface machined at optimal setting of machining parameters for best surface roughness gives Ra value of 4.08 μm. EDS of the machined surface confirms the material migration from tool, as the alloyed layer shows significant increase in percentage of tungsten and carbon. The XRD shows the formation of cementite (Fe 3 C) and tungsten carbide (W 3 C) on the machined surface which is responsible for the substantial increase in microhardness. SEM shows a crack-free surface which indicates that surface alloying has been carried out without any adverse impact on surface quality.
ISSN:0268-3768
1433-3015
DOI:10.1007/s00170-014-6743-1