Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : aluminum alloy


Constant Fatigue Life Under Laser Shot Peening Using Different Surface Coatings

Alakawi H.J.M; Bashar A. Bedaiw; Adel A. Mahmood

Engineering and Technology Journal, 2016, Volume 34, Issue 7, Pages 1275-1283

Laser peening (LP) is a surface treatment technology for metallic materials. LP has shown agreat improvement in the fatigue strength and life.A study of fatigue under constant rotating bending stress programs has been conducted on 7049 AL alloy at a stress ratio (R=-1) and room temperature using laser peening technique .Four groups of tests have been designed.The first group (15 specimens) tested under unpeened condition. The second group (15 specimens) tested under air laser peening (ALP) while the third group (15 specimens) tested under water laser peening (WLP). The last group was designed to examine the fatigue behavior under black paint laser peening (BPLP). All the above groups were designed to establish the S-N curve. The results show no effect of laser peening LP at higher stresses (above 300 MPa), while this effect appears clearly at low stresses (200 and 250 MPa). The results alsoindicated that the WLP is more effective than the ALP. The fatigue life improvement factor (FLIF%) was 39, 18.9 and 4.65 under WLP for 200 MPa, 250 MPa and 300 MPa stress levels respectively.while a clear effect was observed for black paint laser peening (BPLP),it was found that the FLIF % was 93.25 at 300 MPa , 103.24 at 250 MPa and 116 at 200 MPa compared to unpeened data .

Effect of Surface Roughness and Shot Peening Treatments on The Mechanical Properties of Aluminum Alloy 2024 – T4

Alalkawi H. J. M; Ameer Tofan Shafiq; Mohammed khalouk al-azzawi

Engineering and Technology Journal, 2014, Volume 32, Issue 10, Pages 2386-2393

The objective of the present paper is to investigate the effect of surface roughness on mechanical properties of aluminum alloy 2024-T4. This paper describes the effect of surface roughness at values of ( 0.1 , 3.5 , 8 ) μm on hardness and yield strength and also estimate the effect of shot peening on the yield strength at period time of ( 5 , 10 , 15 , 20 , 25 ) min. The obtained results show that the low roughness improved the mechanical properties by 15.7% and also the low roughness is better than the shot peening treatments by 5.3% because the low roughness make surface more coherent. Empirical equations are formulated based on the experimental results to evaluate the yield strength with the surface roughness and the hardness.

Sy= 394.3 ( Ra + 1.35 ) -0.1356
Sy = 1 / 2.2227(10)-2 - 1.32(10)-4 HV

Experimental Study of the Effect of Shot Peening on Elevated Temperature Fatigue Behavior of 7075-T651 Al. alloy

Hussain J. Al-Alkawi; Shakir Sakran Hassan; Salah F. Abd-El-Jabbar

Engineering and Technology Journal, 2013, Volume 31, Issue 3, Pages 416-433

There is a general interest in increasing the fatigue life of materials. Shot peening is the process commonly used in order to increase the fatigue strength and life of 7075-T651. The effect of a combination of processes, fatigue-creep interaction and shot peening has not been thoroughly investigated so far. The aim of the present investigation was whether further improvements can be achieved by a comb/*ination of the two treatments. Two level experiments (cumulative fatigue damage programe) were used in order to determine the optimal set of process. It was found that the combination of shot peening and fatigue-creep interaction could be applied successfully in order to increase fatigue life for some specimens. Results of variable loading test clearly indicate that Miner rule does not give accurate and reliable predictions on fatigue lives.

Effect Of Die’s Shape, Sheet Thickness and Type of Alloy on the Springback Phenomenon

Bushra Rasheed Mohameed; Ethar Mohamed Mhdi Mubarak; Nawal H. Alsalihi

Engineering and Technology Journal, 2012, Volume 30, Issue 9, Pages 1446-1461

In this paper the effect of the springback on the bending operation of different
materials and alloys have been studied. Dies were designed and constructed in
different shape ( U-die , V-die) for several sheet’s thickness. Two types of alloys
were used; Aluminum Alloy 7020 T6 and Brass Alloy. These alloys have different
sheet thickness (2, 4, 6 and 8) mm. Aluminum alloys are heated to 270 °C and
330°C with cooling in the furnace for 90 min. while the brass alloys heated to 300,
320, 340 and 420 °C with cooling for 2 hours in furnace. Bending was done by
using the press of 80 ton. The springback is calculated by published equation. It
can be concluded that, the springback phenomenon caused to enlarge the external
dimensions when releasing the load and thick material have less springback due to
the enlarge of the plastic deformation. It’s found that the die’s shapes have great
effect on the springback, and when the temperature of the specimen is increased,
caused decreased in the springback.

Effect of Hold Time Periods at High Temperature on Fatigue Life In Aluminum Alloy 2024 T4

Mahir H. Majeed; Dhafir S. Al-Fattal; Husain J. Al-alkawi

Engineering and Technology Journal, 2010, Volume 28, Issue 13, Pages 2608-2621

In some applications, the aluminum alloy 2024 T4 may be subjected to an
interaction of fatigue and creep effects at high temperature. This paper investigates
the effect of this interaction by studying the effect of constant amplitude fatigue
(CAF) and creep separately, and then fatigue-creep interaction is introduced by
testing the alloy under constant amplitude with some holding time periods through
the test at high temperature (150 oC). The results showed that the life time of the
alloy decreases due to fatigue-creep interaction as compared to creep alone in
about 77%, and in about 80% as compared with fatigue alone. This is a result of
accumulated fatigue damage superimposed on creep damage. Creep allows more
free spaces for fatigue cracks paths that accelerate failure. A theoretical model to
calculate the time to failure due to fatigue-creep interaction has been proposed.
This theoretical interaction model predicts very close time to failure values to the
experimental results.

Improving Anodizing Efficiency by Adding Different Amounts of Aluminum Powder to Anodizing Electrolyte for Pure Aluminum and Aluminum Alloy (6063)

Uday Sami Mohammad; Sami A. Ajeel

Engineering and Technology Journal, 2008, Volume 26, Issue 7, Pages 842-865

Different amounts of aluminum powder (5, 7, 9 and 11g/l) were added to sulfuric
acid solution of the specimens under ideal conditions previously obtained (1) and the
effect of these additions was studied to find out it's benefit on anodizing efficiency for
pure aluminum and aluminum alloy (6063).
The specimens were examined in different conditions using optical microscope,
roughness and hardness measurements.
The study shows the anodizing process was improved by adding aluminum
powder with ideal conditions and the best value of aluminum powder was 9g/l,
where the thickness improved from 72.25μm at ideal conditions to 81.25μm with
adding 9g/l aluminum powder and the coating ratio improved from 1.481 at ideal
conditions to 1.541 with adding 9g/l aluminum powder for pure aluminum, while the
thickness improved from 74.56μm at ideal conditions to 82.29μm with adding 9 g/l
aluminum powder and the coating ratio improved from 1.417 at ideal conditions to
1.471 with adding 9g/l aluminum powder for aluminum alloy (6063).
The study also shows that the effective anodic current efficiency was increased
about 12.50% when adding aluminum powder of 9g/l compared with ideal conditions
for pure aluminum, while this value was increased about 10.20% when adding
aluminum powder of 9g/l compared with ideal conditions for aluminum alloy (6063)
without adding aluminum powder.
It is found that the surface roughness and hardness value of specimens with adding
aluminum powder of 9g/l gives the best result compared with the specimens at ideal
conditions and bare specimens.