Print ISSN: 1814-6120

Online ISSN: 2311-8385

Volume 17, Issue 2

Volume 17, Issue 2, Autumn 2017, Page 1-50


Effect of Retained Austenite on the Micro-structure and Mechanical Properties of AI-SI4340 High Strength Low Alloy Steel (HSLA steel) Using Magnetic Saturation Measurement and X-Ray Diffraction methods

Basrah Journal for Engineering Science, Volume 17, Issue 2, Pages 1-8

Retained Austenite (RA) has great deal with the mechanical properties of high strength low alloy steel. Therefore,
in this paper, Retained Austenite volume fractions have been
evaluated in AISI4340 alloy steel using two well-known methods, X-Ray diffraction (XRD) and magnetic measurement
methods. The specimens were heat treated using different heating temperature and different cooling rate (different quenching
media). A comparison between the results of two methods
proved that there results were approximately Identical .The
results show that Retained Austenite formation increase as
heating (Austenizing ) temperature increase for the same
quenching media ,as well as ,it increases by increasing cooling
rate . The maximum amount of Retained Austenite found as
(27.2 Wt %) which recognized when the specimens heated up
to 1000˚C then quenched in Water while the minimum amount
of Retained Austenite found as ( 7.06 wt%) when the specimens
heated up to ( 800 ˚C) then quenched in Sand. Hardness tests
using Vickers and Rockwell methods were used and the results
show that hardness values decreased with increasing heating
temperatures and the maximum Vickers micro-hardness and
Rockwell hardness numbers were equal to (121.8HRB) and (
516.35 HV) which were detected when heating up of the specimens were up to 800 ˚C then quenched in water. Tensile tests
show that increasing cooling rate lead to increasing in Strength
due to increasing of hardness which in turn, leads to increase
in yielding points and ultimate strengths. Retained austenite
effects on microstructure were investigated using scanning
electron microscopy (SEM) and optical microscopy and the
results show that at low cooling rate the microstructure consist
of bainite and/or martensite phase with small amount of retained austenite, while, increasing heating temperature and
cooling rate results in microstructure consist of martensite and
retained austenite phases.

Effects of Heat Treatment and Surface Finish on the Crevice Corrosion Resistance of Martensitic Stainless Steel

Basrah Journal for Engineering Science, Volume 17, Issue 2, Pages 9-17

The present study aims to investigate the influence of
heat treatment and surface finish on the behavior of crevice
corrosion resistance of AISI 410 and 416 martensitic stainless
steels thus, to quantify the conditions at which crevice
corrosion minimize as possible. The experimental work carried
out during this study involves material selection, chemical
composition tests, specimens preparation before heat
treatments, austenitizing at temperature range (925-1010˚C)
and for holding time periods of (30, 45 and 90 min), air and oil
quenching followed by tempering at heating range of (205-
605 ̊C) and for 45 min, micro hardness tests, specimens
grinding, surface roughness measurements, crevice corrosion
tests, crevice evaluation and microstructure tests.
Theoretically, empirical equations for crevice maximum depth
under the effect of surface roughness and hardness for both
AISI 410 and 416 steels were determined. While for
microstructure analysis, carbides average area was determined
by using the ImageJ analysis program and a mathematical
model was also predicted. Results showed that like hardness and
surface roughness increase crevice corrosion resistance
decreases. Therefore, material treated by annealing can
minimize crevice corrosion rates more than that treated with
hardening.

Identification and Localization of non-zero Resistance Short circuit Faults in Distribution Feeders Based on the Theory of Wavelets and Artificial Intelligence

Basrah Journal for Engineering Science, Volume 17, Issue 2, Pages 18-32

This paper introduces a radial distribution feeder
protection scheme based on certain features extraction from
current signals measurement at the substation. The features
are captured using the discrete wavelet transform (DWT). Two
digital signals processing methods are used to introduce those
features to the 1) fault detection 2) identification and 3)
localization schemes; the first one is the energy method and the
second one is the root mean square method. For the purpose of
fault type identification, two systems are tested and compared,
a Fuzzy Inference System (FIS) and Artificial Neural Network
(ANN). Fault location scheme is then built based on ANNs. An
effort is made to reduce the computational burden and the
speed of detection provided by the fault detection and
identification schemes. Since the short circuit faults are the
most likely types of faults that can occur in power systems, the
ten types of these faults taking into account different fault
resistances are simulated in MATLAB environment and the
protection scheme is built based on the idea of overcurrent.
The power quality disturbances such as switching transients
events on the feeder are also taken into account in order to build
a reliable and secure protection scheme.

Design and Modeling of a Compact Reconfigurable Slot Antenna for WLAN Portable Devices

Basrah Journal for Engineering Science, Volume 17, Issue 2, Pages 33-37

This paper presents design and modeling of a
compact reconfigurable quarter wavelength slot antenna
compatible with the portable devices of the 5GHz wireless local
area network (WLAN) applications. The concept of the
transverse resonant method which is used for the transmission
lines is utilized for modeling the proposed slot antenna. A PIN
diode is used to switch the antenna operating band from the
lower unlicensed indoor 5GHz WLAN band (5-5.3) GHz to the
upper one (5.7-5.9) GHz and vice versa. Another PIN diode is
attached to the feed line to provide suitable matching stub
length for each operation mode. Furthermore, the shape of the
radiating slot of the proposed antenna is modified to provide
an omnidirectional radiation pattern in the H-plane suitable
for the portable gadgets of the WLAN system. The
measurements are in well agreement with the simulated
results, and they verify the precision of the suggested model
and the enhanced matching characteristics for the two
operation modes of the proposed antenna

Experimental Investigation of the Dynamics of Laboratory Simple Surge Tank

Basrah Journal for Engineering Science, Volume 17, Issue 2, Pages 38-42

The surge tank is one of important control devices in
reducing water Hummer effect on distributed network piping
system and hydropower stations. An experimental study was
conducted into a simple surge tank of 0.044 m in a diameter
with upstream constant head reservoir of a height, 0.881 m
and a water transporting pipe of a size 0.0202 m.
Results indicate that rapid closure of a downstream valve
causes under-damped stable oscillation in a surge tank.
Experimental response agreed well with theoretical results
when friction factor is considered to be variable, but with 85
% increases in settle time and more oscillations when constant
friction factor is recognized at initial value before valve
closure. Doubling surge tank area does not improve the
dynamics properties; otherwise, Thoma area must be avoided
for small sizes. Comsol multiphysics software 3.5 is used to
deal with the dynamics of the surge tank numerically.

A New Fuzzy-NARMA L2 Controller Design for Active Suspension System

Basrah Journal for Engineering Science, Volume 17, Issue 2, Pages 43-50

This paper is concerned with the design of a new
controller for active suspension system. The model is
considered as a quarter-car. The presented controller depends
on the fuzzy technique and NARMA-L2 linearization
algorithm. The compensation system that added by the fuzzy
rules improves the performance of the controller, while the
neural network produces the required control signal. The new
controller can achieve an improvement of the ride comfort
with a reasonable value of power consumption. The
mathematical analysis of the mechanical power used by the
model is focused on the average and the RMS of the power
supplied to the system, regardless of the frequency content of
the vibration signal. The simulation results which are verified
by a practical examples of road profiles, demonstrate the
efficacy of the proposed controller.