Already have an account? Get multiple benefits of using own account!
Login in your account..!
Remember me
Don't have an account? Create your account in less than a minutes,
Forgot password? how can I recover my password now!
Enter right registered email to receive password!
DEVELOPMENT OF COATED ELECTRODES
It was in 1801 when electric arc was first discovered by Sir Humphry Davy while conducting experiments in electricity. In the year 1889, Slavian off, made an attempt to weld with bare wires. But, welding with this gave rise to many difficulties like instability of arc, lack of shielding of molten metal which resulted in poor mechanical properties. In 1920, for the first time coated electrodes were developed. It was found that with a mixture of minerals covering the wire, virtually every aspect of the process could be controlled and improved. The first coated electrodes were called as iron oxide coated electrodes which contained iron oxide and natural silicates in the coating. The weld deposit with this electrode gave poor physical properties because it contained large quantities of gases like Hydrogen, Oxygen and Nitrogen. The coating was further improved upon by adding deoxidisers and denitriders in addition to iron oxide and silicates. These electrodes were known as acid coated electrodes.But, weld deposit by these electrodes also had substantial quantity of gases and most of the useful elements like carbon and Mn were lost in transfer. The coatings employed in those early years of development were thin and their function was more of an arc stabilizer. They did very little by way of purifying or strengthening the weld. The weld was not better than the weld deposits obtained with bare wire electrodes.Further, research in improving coatings gave rise to rutile coated electrodes which have better control in positional welding. In these electrodes the amount of oxygen and hydrogen which was entrapped impaired the physical properties of the weld metal. The rutile coated electrodes had limited use (upto 15 mm thickness of mild steel).The increased use of higher thickness and steels of high tensile properties limited the use of futile electrodes. The main source of hydrogen supply to the weld metal is the water forming compounds and the organic chemicals in the coating. Hence, efforts were made in developing low hydrogen electrodes.
The oxygen, nitrogen and hydrogen content of the weld metal and iron oxide content of the slag decreases as we move down the above list from iron oxide to basic coated types . Also the fillet weld profile clings from a concave profile in case of oxide coated electrodes to convex profile in case of basic coated electrodes.
Describe the following terms:- a) Gyroscope b) Crank-pin effort c) Piston Effort d) Crank effort e) Thrust on crank shaft bearings. f) Brake and Dynamometer g
INTRODUCTION: At any point of time, it may be required to disassemble the whole or any part of motorcycle. Whenever a part of motorcycle malfunctions or is damaged then it may be
Casting processes Casting processes. Here, the metal in the molten state is poured into a mould and allowed to solidify into a shape. The mould may be expendable or permanent.
A vibrating system having mass 1.2 Kg is suspended by a spring of stiffness 1000 N/m and it is put to harmonic excitation of 10 N. Assuming viscous damping, Calculate : (a) R
The average heat transfer co efficient for flow of 100 o C air over a flat plate is calculated by observing the temperature time history of a 3mm thick copper slab exposed 100 o
Q. Why we need Ambient Air Temperatures? Climatic temperatures and humidity conditions will have an impact on the type of equipment selected for the plant. A type of "wind c
I am studying in Final Year of Engineering(Mechanical) and I would like some help for the project. It will be helpful if you suggest some project related to Automation.
a) What are essential needs of a job evaluation plan. Illustrate the point plan method b) Describe factor comparison method of job evaluation. a) What are basic objectives an
Double Refraction An unpolarized plane wave is incident from free space onto a quartz crystal (n e = 1.553 and n o = 1.544) at an angle of incidence 30°. The optic axis lies i
Askquestion #Minimum 100 words accepted#
Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!
whatsapp: +91-977-207-8620
Phone: +91-977-207-8620
Email: [email protected]
All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd