Multiple Choice Questions
1. Which are the three physical properties for generating very high energy densities in the focus point of the laser beam?
A. The radiation is monochromatic.
B. The wavelength is in the infrared spectrum.
C. The radiation has a low divergence.
D. The wave trains of the laser beam are in phase
E. The laser beam is polychromatic.
2. A laser setup consists of what main components?
A. Excitation source
B. Optical resonator
C. Cooling component.
D. Laser-active medium.
E. Beam control.
3. Which laser type are mainly used for material processing ? (choose only one)
A. CO2 laser.
B. Dye laser.
C. Excimer laser
D. Er YAG laser.
E. Semi-conductor laser
4. The choice of the laser-beam source applied depends on?
A. The required laser-beam power.
B.The material to be processed.
C. The material thickness.
D. The surrounding temperature.
E. The efficiency.
5. The CO2 laser ?
A. Is the main beam source that is used for processing tasks in production engineering.
B. emits in the visible spectral range.
C. Is only used for welding and cutting.
D. is mainly guided to processing point via optical fibers.
E. Can be excited with high frequency or with direct current
6. Which are the characteristics of laser-beam welding compared to the traditional joining techniques?
A. High demands on joint preparation.
B. High degree of process automation possible.
C. No filler wire can be used.
D. Lower energy input per length results generally in low hardness.
E. Due to the energy input per length, distortion is significantly lower compared to the traditional shielding-gas techniques
7. Which surface treatments are possible with laser ?
A. Quick heating and cooling results in a significant microstructural refinement when re-melting metals
B. Functional surfaces of components can be hardened locally.
C. Allows a high surface output when surfacing due to the laser beam powers of 6000W.
D. Small complex components cannot be surfaced without distortion.
E. Due to the high laser beam power, no small components can be hardened.
8. Laser welding is performed with freedom of electrode contamination
9. Which of the following does not hold true about laser beam welding? (choose only one)
A. Laser welding cannot be used in case of joints at intricate locations
B. It can produce tiny welds
C. Laser welding can be used for variety of metal combinations
D. In case of LBW, thin welds on small diameter wires are less susceptible to burn back
10. Laser welds are not influenced by (choose only one)
A. electric field
B. magnetic field
C. radio waves
D. Ultraviolet rays
11. Attainable by LBW aspect ratios: depth-to-width ratios are (choose only one)
12. Conduction mode laser welding is performed with energy density of (choose only one)
E. None of the above
13. The joining efficiency and the energy spent during the welding process are directly proportional in LBW.
14. During laser welding, any hump on the surface can cause
A. increase in weld porosity
B. flow instability
C. higher energy absorption
D. decrease in the weld thickness
15. The maximum welding speed in laser welding process varies directly with the power
16. Which of the following is not affected by the speed of welding? (choose only one)
A. Weld pool size
B. Weld pool flow pattern
C. Weld bead
D. Focal position
17. Which of the following is the common problem on welding aluminum by laser welding?
C. Less grain growth
D. Brittle weld
18. Which of the following is the problem on welding heat resistant alloys by laser welding? (choose only one)
A. Brittle welds
B. Hot Cracking
D. High power consumption
19. The improved coupling for the case of welding of high reflectivity materials using twin beam lasers is due to (choose only one)
A. surface rippling
B. surface tension
C. surface smoothness
D. surface area
20. At high speeds in laser welding process, undercut occurs
21. Relative distance of arc and the laser beam is important parameter in hybrid laser welding process
22. The power for hybrid welding sources are mainly depends upon
A. Thickness of the materials.
B. Properties of the materials
C. Welding groove.
D. Thermal conductivity of materials
E. Melting point of materials
23. Which statements are correct about hybrid welding process over laser or arc welding process?
A. Low distortion.
B. High welding speeds
C. High productivity
D. High susceptibility of porosity
E. Arc instability
24. Which purpose does the vacuum in the electron-beam machine serve? (choose only one)
A. It protects the anode.
B. Less energy is required.
C. It protects the cathode.
D. It is more environmentally friendly.
E. The voltage can be lowered.
25. For which purpose do you need the cathode in EB welding ? (choose only one)
A. For emitting the electrons.
B. For acceleration the electrons.
C. For focusing the electrons.
D. For beam shaping.
E. For adjusting the beam direction
26. Which advantages does EB welding provide compared to laser welding ?
A. Welding in vacuum is possible.
B. Slightly oily sheet materials can be welded.
C. The limiting weld-penetration depth is 30mm.
D. A weld width/weld depth relation of up to 1: 40 is possible.
E. No fading solidification in welds on aluminum materials
27. What are applications for electron beam processing?
D. Surface treatment
28. In the last stage of electron beam gun, electron beam passes through the electromagnetic lens and deflection coil.
29. In electron beam welding, the common defects formed are
B. Spatter formation
C. Slag formation
D. Under cuts
30. For welding Aluminum and Copper alloys, EBW requires chemical cleaning for degreasing to avoid defect formation
31. Electron beam welding is influenced by the magnetic field
32. Which metals are easily to weld with electron beam welding?
A. Low-alloy steels
C. Structural steels
D. Cast iron
E. Heat treated steels
33. At higher energy densities, material removal rate is high in electron beam welding process
34. Advantage of using electron beam welding is / are (choose only one)
A. Welds are clean
B. Absence of porosity
C. Distortion less
D. All of these