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Right answer is (c) Heat Affected Zone

For explanation: HAZ STANDS for Heat Affected Zone. This zone is generally the base of the METAL or a thermoplastic material. This zone is not MELTED but the properties are altered by the WELDING PROCESS.

Right option is (b) False

Explanation: Before the welding starts, the MACHINE has to be adjusted very CORRECTLY. The current to be supplied and the voltage to be applied should not to be too low or high, and the welding speed should be normal. By doing this, REGULAR and smooth beads will be formed.

Correct CHOICE is (b) 3900°C

The EXPLANATION is: Carbon is used in carbon arc WELDING, at the NEGATIVE terminal of the cathode and the metal which is being worked upon FUNCTIONS as the positive terminal. The temperature of the electrode at the positive terminal is 3900°C.

Correct OPTION is (a) 0.1% to 0.18%

The explanation: A SOFT steel wire contains about 0.1% to 0.18% of carbon. Soft steel wire also has other contents in it like phosphorous and SULPHUR in it. The amount of phosphorous is soft steel is AROUND 0.0025%.

The correct choice is (d) 400 Hz

Explanation: In an arc WELDING process, there are ALTERNATORS used for producing high current and function at lower FREQUENCY, and there are alternators which are of high quality and work at high frequency. The FUNCTIONING frequency of these alternators is 400 Hz.

Correct option is (a) True

To explain I would SAY: In GAS WELDING, a welding torch is mainly used for mixing oxygen and ACETYLENE in the desired proportions. It is also used for burning the mixture at the end of the tip, and also provides a mean for moving and directing the flame front. Welding torch can be of high pressure type or LOW pressure type.

The CORRECT option is (B) Percussion

The EXPLANATION: AMONG the following, soldering, pressing and hard-pressing are few of the types of related PROCESSES. Percussion is one of the forms of resistance welding processes.

Right answer is (d) 2.5 mm

Explanation: WELDINGS such as spot WELDING or CONTINUOUS SEAM welding can be done through ultrasonic welding. The maximum thickness that can be achieved VARIES depending on the metal. The maximum thickness can be that can be welded is 2.5mm.

The correct answer is (c) Excess splatter

To explain I would say: On provision of too low current, there is pilling of metal SEEN. When the voltage provided is very high, beads FORMED are too high. When the speed of weld is less, pilling of weld metal takes place and when welding CURRENTS are too high, excessive splatter FORMATION occurs.

Correct ANSWER is (d) Steel

Explanation: Materials that are used as COATING on the electrode, that are used in arc welding, are CELLULOSE, iron powder, calcium fluoride and rutile. Iron is used for ease of weld, but not steel, though it mainly contains iron.

Correct option is (b) False

Explanation: During the OPERATION of the arc WELDING PROCESS, the positive pole of the electrode experiences two third of the heat and the negative pole experiences one third the heat, HENCE the positive pole burns away FASTER than the negative pole.

Right option is (C) 0.25%

The explanation is: The amount of carbon that is present in a SOFT STEEL wire is around 0.1% to 0.18% and the amount of carbon in TERMS of percentage composition in low alloy steels is 0.25%.

The correct option is (b) PROVISION for OXIDATION to MOLTEN metal

Easy explanation: On weldability, there are some effects seen in the alloying elements. Some of them are Control of ductile-malleable TRANSFORMATION temperature, Reduction in segregation, Grain refinement and provision for deoxidation to the molten metal.

Right choice is (a) 3200°C

Best explanation: When equal amount of OXYGEN and acetylene is MADE to REACT in a TORCH, a neutral flame gets PRODUCED. The inner core has a temperature of 3200°C, whereas the tip of the neutral flame has a temperature of 1250°C.

The CORRECT ANSWER is (a) HAND lever

To ELABORATE: NONE.

Correct CHOICE is (d) 3200°C

Best EXPLANATION: Acetylene gas is a TYPE of fuel gas that is USED for the WELDING of thin sheets of steel which have a thickness of up to 50 mm. The flame temperature of acetylene gas is approximately about 3200°C.

Right answer is (b) Second

The explanation: A MULTI run PROCESS causes a good AMOUNT of grain refinement. With every proceeding run weld, it normalizes its previous run. In ORDINARY STEELS, grain refinement takes place in the second run.

The CORRECT choice is (b) Decreases

Easy explanation: In ARC welding processes, for CALCULATING the efficiency, we USE the formula for heat input. According to the formula, heat input is inversely related to the speed of welding, that is, with an increase in heat input, the welding speed decreases.

Right answer is (a) Boiling point

For explanation I WOULD say: Weldability is dependent on five factors of the metal or alloying element. The factors being, melting point, thermal EXPANSION, thermal conductivity, surface CONDITION and CHANGE in the MICROSTRUCTURE.

The correct answer is (b) False

The explanation is: Upset butt WELDING is mainly used for the MANUFACTURE of welding BARS, rods, wires or tubing. For the manufacture of automobile PARTS, such as axles, wheels or frames, flash butt welding is extensively used.

The correct choice is (c) Acetylene

To EXPLAIN I would say: Gas welding is usually referred as oxy welding or oxy-FUEL welding which is a process of joining metallic materials by application of heat PRODUCED by the gas flame. In gas welding, acetylene is COMMONLY used as fuel gas which mixed with proper proportion of oxygen in a mixing CHAMBER of welding torch. Gas welding can produce a hot flame of temperature about 3000-3500 ⁰C.

Right option is (b) Steel

Easiest explanation: Cold WELDING process is not very suitable for alloys like steel, the reason being, cold welding cannot take place excellently in ferrous materials. Steel contains high amount of IRON, HENCE it cannot be cold WELDED.