INVESTIGATION OF EDGE CRACKING PROPENSITY IN COLD-ROLLED COMMERCIAL ALUMINIUM ALLOY 8011 UNDER MIXED OIL LUBRICATION CONDITION
INVESTIGATION OF EDGE CRACKING PROPENSITY IN COLD-ROLLED COMMERCIAL ALUMINIUM ALLOY 8011 UNDER MIXED OIL LUBRICATION CONDITION
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Date
2014-07
Authors
YAKUBU, HASSAN ONIMISI
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Abstract
The effect of iron content on edge cracking tendency in cold-rolled commercial aluminium alloy
8011 under a mixed coconut/diesel oil (factory formulated oil) lubrication condition and under
neem seed oil as an alternative has been investigated. Three different aluminium alloy plates
each containing 0.708%Fe, 0.909%Fe and 0.931%Fe were produced by chill casting method.
Seven samples each of dimension 240mm x 140mm x 7mm were cast per alloy. As-received
commercial aluminium alloy 8011 of 0.857%Fe was cut into seven samples of the same
geometry. Experimentation involved cold reduction in thickness by rolling at various degrees of
deformation, followed by testing of mechanical properties and qualitative metallographic
analysis. Performance evaluation of mixed coconut/diesel oil and neem seed oil lubricants in
friction reduction of cold-rolled commercial AA 8011 and proportion of mixture of coconut and
diesel oil that will give the highest percentage deformation were also conducted by plane strain
compression test. From the results obtained, it was observed that aluminium alloy 8011 generally
exhibited softening characteristics as shown by its maximum ultimate tensile strength of
176.45MPa at 60% reduction in thickness and on reaching the peak hardness values, all samples
displayed decrease hardness for given levels of percent reduction in thickness. It was also
observed that for up to a maximum of 0.931%Fe, AA 8011 could be cold-rolled to a maximum
of 60% reduction in thickness without any evidence of edge cracking. Alloys with 0.909%Fe and
0.931%Fe, edge cracked at 70% and 80% reductions in thickness and the other alloys showed no
edge cracking for the whole percentage deformations investigated. Furthermore, samples of AA
8011 containing more than 0.9%Fe revealed higher tensile strength when cold-rolled to 80%
reduction in thickness. The results of plane strain compression test showed that at any specific
load, neem seed oil provided better lubrication; about 106% reduction in thickness better than
mixed coconut/diesel oil at100kN load. The mixture of locally sourced coconut and diesel oil in
different proportions performed best in friction reduction at the ratio of 30% coconut oil and
70% diesel.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA.
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF A
MASTER DEGREE IN METALLURGICAL AND MATERIALS
ENGINEERING
DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING,
FACULTY OF ENGINEERING
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA.
JULY, 2014
Keywords
INVESTIGATION,, EDGE,, PROPENSITY,, CRACKING,, COLD-ROLLED,, COMMERCIAL,, ALUMINIUM,, MIXED OIL,, LUBRICATION,, CONDITION