(SEM V) THEORY EXAMINATION 2020-21 ADVANCED WELDING

SECTION A (Any 2 Questions Explained Briefly)

What do you understand by weldability?
Weldability is the ability of a material to be welded easily under given fabrication conditions and to produce a sound joint without defects. It depends on factors such as chemical composition of the material, welding process used, cooling rate and pre- or post-weld heat treatment. Materials with good weldability form strong and crack-free joints.
 

What is the physics of arc welding?
Arc welding works on the principle of electrical arc generation between the electrode and the workpiece. When electric current flows across a small gap, intense heat is produced due to ionization of gases, forming an arc. This heat melts the base metal and filler metal, which on cooling forms a strong welded joint.
 

SECTION B (Any 2 Questions Explained)
 

Define Schaeffler diagram and explain its importance.
The Schaeffler diagram is a graphical tool used to predict the microstructure of stainless steel weld metal based on chromium equivalent and nickel equivalent values. It helps in estimating the amount of ferrite, austenite or martensite formed after welding. The diagram is important because it helps avoid weld defects such as cracking and ensures proper selection of filler material.
 

Explain types of underwater welding.
Underwater welding is classified mainly into wet welding and dry welding. In wet welding, the welding is performed directly in water using waterproof electrodes, while in dry welding the weld area is enclosed in a chamber filled with gas. Wet welding is simple and economical, whereas dry welding provides better quality welds and improved safety.
 

SECTION C (Any 2 Questions Explained)
 

Explain different types of welding power sources.
Welding power sources supply electrical energy required to maintain a stable arc. The main types are constant current and constant voltage power sources. Constant current sources are commonly used in manual welding processes, while constant voltage sources are preferred for automatic and semi-automatic welding. The choice of power source affects arc stability and weld quality.
 

Explain the need of welding automation.
Welding automation is used to improve productivity, consistency and quality of welds. Automated welding reduces human error, increases welding speed and ensures uniform heat input. It is widely used in mass production industries such as automobile and shipbuilding.
 

Most Questions in This PDF Are Related To
 

Most questions in the Advanced Welding (KME-055) paper are related to welding processes and principles, weld metallurgy, power sources, thermal effects in welding, weld defects, testing methods, automation, safety, and special welding techniques like underwater, friction, GTAW, GMAW and advanced welding processes. Overall, the paper focuses on modern welding technologies and their industrial applications.