Promoting Material Properties of Magnesium Alloys using Equal Channel Angular Press

 
The Problem with Magnesium alloys
The fact that Mg alloys have lower mechanical strength and corrosion resistance due to a low number of slip systems and a higher corrosion tendency respectively are some of the technical challenges. The key to improving the performance of magnesium alloys is refining the grain size and distributing secondary phases by using thermo-mechanical processing. Mr Gajanan M Naik and Dr Narendranath S of the Department of Mechanical Engineering at National Institute of Technology Karnataka, India, study the effectiveness of grain refinement by equal channel angular pressing using route-R at a 90⁰ and 110⁰ channel angle by treating the 30⁰ corner angle as a constant. They found that the Mg alloy processed through a 90⁰ channel angle possess improved mechanical and corrosion properties and this angle provide more effective grain refinement when compared to a 110⁰ channel angle, rendering them valuable to improving the properties of Mg alloys.

ECAP to the Rescue
Equal channel angular press can be used to strengthen the material properties of Mg alloys, so that it helps greatly to reduce grain size and significantly distribute a secondary phase in the matrix. The mechanical properties and corrosion resistance significantly improved when Mg alloy processed through ECAP. Nevertheless, the material properties of Mg alloys achieved through processing with 90⁰ die angle are significantly higher than an Mg alloy processed with 110⁰ die angle, meaning the lower the channel angle, the higher the grain refinement.

The Flipping Type Die
Dr Narendranath S and his students have successfully fabricated flipping type ECAP die with 90⁰ and 110⁰ channel angle die, capable of sustaining the heavy load. One of the challenges for using ECAP is that their large sizes can make it difficult to handle during experimentation.

The ECAP processing that Dr Narendranath S and his students have pioneered shows the greater enhancement of mechanical and corrosion resistance due to effective grain refinement, the improved corrosion resistance, meaning it could potentially show the higher E_corr and lower i_corr values. They have also been working to impact of texture on corrosion behaviour after ECAP. Based on the results few publications are published in international journals.

Background
V.M. Segal and his colleagues have carried out their first significant study in Minsk in the 1970s, as ECAP was emerging as an important new severe plastic deformation technique. In the study, the researchers investigated the potential of using ECAP to improve mechanical properties of various materials. Along with this, P Minárik et al., Gholami‐Kermanshahi et al., K.R Gopi et al. and I Son were working to improve the corrosion resistance of Mg alloys through ECAP. The team found that when using ECAP with different channel angle and processing routes, the performance of the material in measuring mechanical properties and corrosion resistance was significantly improved. Using the tools ANSYS and abacus with different channel angles, including number of pass, they were able to simulate the results. This numerical study based on effect of channel angle, corner angle, coefficient of friction was appraised and published in various international journals. Thus, Professor Narendranath and his students’ study revealed the importance of channel angle during ECAP in order to achieve improved mechanical properties and corrosion resistance.

Approach
During the Naval Research Board (NRB) project in 2016, Professor Narendranath S, and his students unveiled their plans for the NRB Project. “The aim of the project is to study the mechanical properties and corrosion resistance of ECAPed Mg alloys response to industrial applications,” says Dr Narendranath S. “Several aspects of the project required the design and development of ECAP die and procurement of electrochemical corrosion analyser for experimentations.”

A Promising future
Dr Narendranth S and his research group are optimistic that ECAPed Mg alloy could someday replace high-density material in modern devices such as electronics, specifically in the automobile, aerospace and marine fields, which require ever-light, high-strength materials with improved corrosion resistance. “Through the ECAP combined grain refinement and distribution of secondary phase, Mg alloys can potentially be used for engineering applications,” said Dr Narendranath S. Much is still unknown about the nature of Mg alloys and the knowledge imparted by Dr Narendranath S research has shown that the ECAP is a valuable tool for improving the properties of Mg alloys, as well as contribute enormously to future electronic technological breakthroughs.

Behind the research

Research objectives

Mr Gajanan M Naik and Dr Narendranath S’ research aims to improve the mechanical properties and corrosion resistance of magnesium alloys.

 
Details

Bio

 
Funding

Naval Research Board- NRB/4003/PG/366, India.

Research Scholars

Mr. Prithiviraj Sekar (Ph.D. Onging)

Mr Mayur (M.Tech. Onging)

Collaborators

Dr Satheesh Kumar S S, Scientist, Near Net Shape Group, Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500058, Telangana, India

Personal response

The main objective of this research work is to develop extruded magnesium alloys with improved properties compared to the current obtainable products on the market. We have established an ECAPed specimen that enhanced mechanical properties and corrosion resistance. We believe that ECAPed Mg alloys can be used in all engineering applications and contribute to the reduction of weight and fuel consumption.  Now we are actively aiming for galvanic corrosion and stress corrosion cracking study for ECAPed Mg alloys. At the same time, we are working towards the practical use of ECAPed Mg alloys.