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Register a new userCorrosion ofWelded Stainless Steels and Nickel Alloy in Polluted Industrial Phosphoric Acid Media
تآكل وصلات اللحام لبعض أنواع الفولاذ غير القابل للصدأ و إحدى خلائط النيكل في حمض الفوسفور الصناعي المشوب
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بينت التجارب وجود تباين واضح في كلٍ من كثافة تيار التآكل و معدلات التآكل للخلائط المختبرة، كما اتضح توافر اختلاف كبير بين معدل التآكل لمعدن الأساس و مثيله لمعدن اللحام في أغلب الأنواع المدروسة من هذه الخلائط، مما يسبب معدلات تآكل عالية للوصلة اللحامية و تغيراً في خواصها، و خروجها من الخدمة في بعض حالات الاستثمار.
Welded joints corrosion phenomena for some kinds of stainless steels and nickel alloy was studied in polluted phosphoric acid 37.7%H3Po4 using electrochemical techniques like Tafel polarization. Corrosion rate of base metal and weld metal had calculated & compared among these alloys. Laboratory Test results showed the change in both corrosion rate and corrosion current densities (Icorr) for tested alloys, and there is a clear difference between base metal and weld metal in most of tested alloys , which lead to high corrosion rates of welded joint, and change in its properties then gets out of service in some service conditions. The stainless steel 904L has low corrosion rates and low difference in corrosion rates between base metal and weld metal, so it may be the most suitable alloy, among all the studied alloys, for exploitation in polluted phosphoric acid 37.7%H3Po4 produced at the General Fertilizer Company in Homs city.
References used
J. Mendoza-Canales and J. Marín-Cruz, Int. J. Electrochem. Sci., 3 (2008) 346
A.Y. Musa, A.A.H. Kadhum, A. Bakar- Mohamad, A. Razak-Daud, M. Sobri-Takriff, S. Kartom-Kamarudin and N. Muhamad, Int. J. Electrochem. Sci., 4 (2009) 707
P. Barraco, G. Chiaro and A. Barbera, Nutr. Cycl. Agroecosyst., 26 (1990) 281
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This research showed the great importance for following studies of the effect of polluted phosphoric acid,
produced in General Fertilizer Company, on the high corrosion resisting alloys, to reach suitable alloys
for equipments and machines used for
its production, because of its high corrosion rates that create many
corrosion problems in these equipments and machines.
The corrosion behaviour of plain-carbon steels in water environments has been studied. In
this study, a wide range of carbon steels are used in the most common corrosion environments
which are salt water and drinking water. The specimens were immer
sed in the water media and corrosion rates evaluated, using the weight loss method. The effect of
carbon content, corrosion environments and time of immersing on the specimens corrosion
rates of Hypo-eutectoid plain carbon steels have been studied. The aim of this work is to study
the effect of carbon content on the corrosion rate of carbon steels in different corrosion media
and various time intervals. The obtained results showed that there is a clear correlation with
the microstructure where higher Pearlite show higher corrosion rate, so the corrosion rate
increases with the carbon content. The results also show that the corrosion rate of carbon-steel
in salt water is higher than its value in drinking water. It is also found that longer exposure
time, leads to a lower corrosion rate while weight loss is still increasing.
Phosphoric acid is one of the most important products in
chemical industry, where it is used in different industries,
such as food and fertilizer industries and so on .
This study focuses on the preparation of phosphoric acid
from Syrian phosphate in the laboratory by using the
hemihydrate method , and determines the best optimal
conditions for preparing this acid using this method .
Design of experiments (DOE)
had been used in the study, and the results had been evaluated by the
surface response method. The results showed that the welding
current is the main parameter by its effect on the mechanical studied
properties and the parameters values which give the best responses
had been determined.
The aim of this work is to study the effect of the aging heat treatment on the pitting corrosion resistance of martensitic stainless steel. In this research a number of specimens from martensitic stainless steel were subjected to solution treatment a
t 1050 for one hour followed by water quenching then aging in the temperatures range (400-750) for different holding times (1-16 hrs).
After heat treatment, two types of corrosion tests (accelerated test and immersion test) were conducted. The results obtained in this research showed that the pitting corrosion resistance was
affected by Aging temperature and three critical temperatures were found in corrosion test: the
specimens aged at 475 0C had maximum corrosion rate. This may be due to the presence of stringer δ-
ferrite and precipitation of very fine precipitates which precipitated heterogeneously in the martensitic
matrix, which led to an increase in corrosion rate. The specimens aged at temperatures range (550 – 625) 0C had minimum values of corrosion rate, this is attributed to the high volume fraction of retained austenite. The specimens aged at temperatures above 625 had intermediate corrosion rate.
The type of pits, which resulted from two pitting corrosion tests, was independent form the form of δ-ferrite and carbides which presence in microstructure.
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