University of Botswana
Faculty of Engineering and Technology
Department of Mechanical Engineering
IMB 325 – Tutorial #4
Date: Friday, April 25, 2025
1. (a) With the aid of sketches demonstrate five common techniques or methods of
joining materials.
(b) Figure Q1 (b) shows hardness profiles of various metal alloys across a common
path on the respective weldments.
(i) Give an account of why there is a noticeable trend of a higher hardness value
for all alloys around the dotted line marked “Hmax”.
(ii) Comment on the possible compositions of alloys CR1 and TM1, and why
they would show such significant differences in behaviour.
Figure Q1 (b): Hardness analysis across a weldment for various metal alloys.
(c) Briefly discuss the significant difference, if any, between brazing and welding.
2. Figure Q2 one below shows a typical welding process in use. Study it and answer
the question that follow.
Prepared by: Uananisa H J
Figure Q2: Welding Process.
(a) Name this type of welding in full.
(b) State what the shielding gas on the diagram is useful for, and how it assists
in achieving this particular use.
(c) State the typical candidate materials from which this shielding gas is made
from, and their full chemical name.
3. List four (4) different types of welding processes, and through the aid of sketches
or otherwise illustrate the significant differences between them.
4. Figure 2 below shows a schematic of a welded joint of two base metal pieces. Study
it carefully and answer the questions that follow.
Figure 2: A schematic diagram of a welding joint.
(a) Identify clearly the regions marked ‘A, B, C and D’.
(b) Copy the schematic above and sketch the likely microstructural distribution
you are likely to observe after such a welding process, with the joint
quenched in cold water after welding.
Prepared by: Uananisa H J
5. Figure 3 below shows two types of surface profiles of a weldment, ‘E and F’.
Figure 3: Surface profiles after a welding procedure.
(a)
(b)
(c)
Name these two types of surface profiles respectively.
State which one of these surface profiles is preferred in a weld, elaborate
why this is so.
List five (5) possible welding flaws and explain how each one of them
normally occurs in a weldment.
6. Study the Figures Q6 (a) and (b) below and answer the questions that follow.
(a) Briefly discuss why there is a noticeable variation in hardness between allows “1
and 2” in Figure Q6 (a).
(b) Why does alloy “3” in Figure Q6 (a) have an almost constant value of hardness.
Prepared by: Uananisa H J
(c) Briefly explain why they are some distinct peaks in hardness (A, B, C and D) in
Figure Q6 (b) above.
(d) List five (5) different methods used in practice to detect welding imperfections, and
also explain briefly how each method is performed.
7. Figure Q7 below shows a temperature distribution during the welding of a
hypereutectoid steel. The welded segment was then quenched in water at room
temperature for cooling.
Figure Q7: Schematic temperature distribution in a hypereutectoid steel.
(a) Sketch the likely mechanical strength profile of this steel after such a weldment
across the line numbered 1 to 11 above.
(b) From (a) above, discuss why you would expect this noticeable variation in strength
across the weldment.
Prepared by: Uananisa H J