JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III METAL JOINING TECHNOLOGY Previous Question Paper (November/December - 2017 - R15)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit. Each question carries 10 marks and may have a, b, c as sub questions.
Part A
Differentiate between gas welding and arc welding.
Answer
Gas welding uses the combustion of fuel gases (like acetylene) with oxygen to produce heat, whereas arc welding utilizes an electric arc between an electrode and the workpiece to generate heat. Gas welding is generally slower with a broader heat-affected zone, while arc welding offers higher energy density and faster welding speeds.
What is HAZ and draw and label it?
Answer
The Heat Affected Zone (HAZ) is the portion of the base metal that has not been melted but has had its microstructure and mechanical properties altered by the welding heat. It is located between the fusion zone and the unaffected base metal. Visually, it is represented as a region adjacent to the weld bead where thermal gradients have caused grain growth or phase transformations.
What are the factors which effects welds?
Answer
Sign in to view the complete answer paper.
How diffusion welding is deferring from normal welding?
Answer
Sign in to view the complete answer paper.
What are transformational stresses and give its factors?
Answer
Sign in to view the complete answer paper.
What is the role of joint geometry on welding?
Answer
Sign in to view the complete answer paper.
What is weldability?
Answer
Sign in to view the complete answer paper.
What is Knife Line attack and how it can be minimised?
Answer
Sign in to view the complete answer paper.
What is NDT and how it is useful for welds?
Answer
Sign in to view the complete answer paper.
What is the function of a developer?
Answer
Sign in to view the complete answer paper.
Part B
What are the sources of gases in welding process?
Answer
Sign in to view the complete answer paper.
What are the major gases that causes trouble during welding and list out troubles.
Answer
Sign in to view the complete answer paper.
Differentiate between soldering and brazing.
Answer
Sign in to view the complete answer paper.
Discuss briefly about the absorption of gases by welds.
Answer
Sign in to view the complete answer paper.
What are the special features of Plasma Arc welding? Compare and contrast between un-transferred and transferred plasma arc process.
Answer
Sign in to view the complete answer paper.
In a GTAW process, the arc voltage is 24 Volts, the arc current is 200 Amperes, voltage drop at cathode and anode are 9 and 5 volts respectively and 75% of the arc column energy is untransformed. The work function for Tungsten is 4.5eV and Boltzmann’s constant = 8.62 × 10-5 eV/K. Find out the arc efficiency.
Answer
Sign in to view the complete answer paper.
State the working principle, construction of the equipment, process, and effects of the process variables, applications and limitations of the following process:
a) Laser Beam Welding
b) Ultrasonic Welding
Answer
Sign in to view the complete answer paper.
Briefly Explain pre & post heat treatment of martensite steel weldments.
Answer
Sign in to view the complete answer paper.
With a Sketch explain changes that are taking place in HAZ of 0.5% carbon steel.
Answer
Sign in to view the complete answer paper.
Discuss preheating and post heating in weldments.
Answer
Sign in to view the complete answer paper.
Distinguish between weldability and Cuttability with suitable examples.
Answer
Sign in to view the complete answer paper.
Write short notes on welding of cast Iron.
Answer
Sign in to view the complete answer paper.
What is the role of carbon equivalent on welding of steels and cast irons?
Answer
Sign in to view the complete answer paper.
Write short notes on welding of Cu alloys with respect to process, difficulties, microstructure, defects and its remedial measures.
Answer
Sign in to view the complete answer paper.
State the causes and remedy for the following defects:
a) Slag inclusion b) Lamellar tearing c) Hot crack d) Lack of penetration
Answer
Sign in to view the complete answer paper.
State the causes and remedy for the following defects:
a) Cracks b) distortion c) under-cutting and d) overlapping
Answer
Sign in to view the complete answer paper.