MOD002634 Materials and Processes Report: Engineering Applications

This report delves into the realm of materials and processes, commencing with an exploration of composite materials. It examines their evolution, types like fiber-reinforced plastics and metal matrix composites (MMCs), applications in diverse industries (automotive, leisure), advantages (weight reduction, high strength-to-weight ratio), and disadvantages. The report also covers manufacturing methods such as squeeze-casting and powder metallurgy, alongside maintenance and recyclability considerations. The second part of the report focuses on welded and brazed specimens, analyzing various welding techniques (fusion, solid phase) and identifying potential faults like porosity, discussing the metallurgical effects of these processes. The final section addresses material failures, presenting case studies of component failures (cast aluminium collet, stainless steel pipes, cam shafts, and gears), identifying causes (corrosion, wear, fatigue) and suggesting remedial measures. The report concludes with a description of corrosion, its types and its effects.

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Chapter 1
Introduction
There has been evolution of the modern composite materials which has assisted in the provision
of tailor-made’ materials of high performance for the advanced technology and engineering
fields. The evolution of the composite materials started with the development of fiber reinforced
plastic which are commonly known as FRP composites. This could be traced back to the year
1930s. It later graduated to metal matrix composites commonly known as MMCs as well as
ceramic matrix composites which is also being refered to as CMCs.
Metal matrix composites or MMCs refers to a class of composite materials which are of
relatively low strength, light in weight and constitute majorly alloys of magnesium, aluminum of
titanium. These alloys are added additional stiffness and strength through introduction of second-
phase particles, fibers, whiskers, filaments and wires (Islam et al 2014). The common one is
MMCs.1–4. Some of their applications include in automotive industries in making propeller
shafts, engine-connecting rods as well as brake disks. In the case of the industry of leisure, it is
used in the manufacture of frames of the bicycle as well as racquets of tennis. The efficiency of
use in most of its application includes among others the weight reduction.
The focus on the use of the MMCs has been on particularly aluminium matrix that has been
reinforced with fibers or particles of alumina or silicon carbide. This is due to the fact that they
possess very attractive properties mechanically like high wear, high resistance, high strength to
weight ratio, high resistance to temperatures as well as low density. Some of the routes which
have been used for processing include squeeze-casting, liquid metal infiltration and finally
powder metallurgy.

PCDs have been use in machining of other materials including hypereutectic aluminum-silicon
components of alloy, abrasive plastics, non-ferrous alloy of copper, composites of wood such as
MDF and chipboard among others. In the previous years there was recommendation of the use of
the PCD as the most effective tool to be used in MMCs machining. However, there is ultra-
precision turning of MMCs. This is done at very low depths and feed rates of cuts by the use of
the single point diamond tools (SPDT).
Also in applications are the tools of the PCD which have varying geometries. The
demonstrations have shown that a nonmetric level of surface finish can be achieved in the case of
the MMCs materials. One of the primary characteristics of the tools from PCS is the sharpness
of their edges. This implies that in the cases of the application of the tools of PCD. This implies
that in cases of their applications, the subsurface zone reinforcement are usually cleanly cut
leaving them nearly undamaged. Applications of other material tools tend to pull the
reinforcements or fracture it out instead of having them cleanly cut.
Composites Applications
Composites of shape memory polymers They are basically high performance
composites
Their formulation involves the use of fabric or
fibre reinforcement.
They can be reshaped after being reheated
repeatedly without necessary having their
properties lost
They are used in the application of light,

deployable
Carbon Fiber Aircraft industry : Fiber is known to bond well
with surface treatment. They are good fatigue
and usually show non-susceptibility to
chemicals (Kanemaru et al.2014)
Glass fiber Used in making components of the aircrafts.
They have strength greater than 3Gpa. This is
as a result of small diameter fiber defects.
Advantages/ Benefits of composite materials
 The overall structural member weight is usually reduced by composites by around 20%-
50%
 They are resistant to fatigue and corrosion
 Their mechanical properties are generally tolerable.
Demerits /Disadvantages
 They generally have high recurring costs
 Their material costs are higher
 Their maintenance and repair is generally expensive
 Some of the need isolation so as to prevent for the galvanic corrosion from the adjacent
aluminium.
Methods of Composite Manufacture:
 Closed molding
 Open molding

 Cast polymer molding
Maintenance or repair of the composites e.g FRP
Patch method of maintenance: This is the most common repair method which is carried on the
composites particularly those of FRP. The method is low cost besides being simple. Other than
being fast to carry out, it is functional and tends to be ideal when urgent field repairs are
required. Depending on the application, it can neither be permanent or temporary (Hillen et
al.2014). The configuration of the repair technique is as shown in the figure below:
Figure 1: The configuration of the repair technique (Tan, and Shin 2015)
Patch can also be used in the improvement of the existing strength particularly in the case of
structures that are undamaged (Kreindl, and Glanseck, Fronius 2014).
Recyclability of the composites
Materials of composites are usually known for their high strength, durability, low maintenance,
excellent quality as well as low weight. As a result they have had their applications in the
construction, transport, automotive, renewable energy and finally aerospace industries. This
implies that their recyclability must be increasingly given attention. Initially, there were limited

operations of commercial recyclability in the case of mainstream materials of composites as a
result of technological as well as economic constraints. However, with the rise of the R&D
activities, composites can be recycled through reheating and reshaping.
Chapter 2
Part one
Figure 2: Specimens Single pass arc weld in plain low carbon steel
Figure 3: Low carbon steel arc weld.

Figure 4: Fusion weld between plain carbon steel and an alloy steel
Figure 5: Bronze weld in brass plate
Figure 6: Fusion weld between pipe and plate (compensation plate).

Figure 7: Multi pass weld in low carbon steel.
Figure 8: Submerged Arc weld in large sectioned low carbon steel plate.

Figure 9: Tee piece in low carbon steel
Figure 10: Friction weld in carbon steel
Part two
Identified Faulty in the welds

There was porosity effects which might have been caused by the contamination effects in the
welding shown below
Figure 11: Identified porous areas
Part of the remedy would be cleaning the surfaces before welding started.
Part three
Solid phase welding
Involves joining of two workpieces through pressure application so that intimacy contact is
created with the temperature being below the melting point (Panneerselvam and Lenin 2014).
Applications
 It is used in the joining of metals which are dissimilar.
Limitations

Non-fusion
 Parts are joined by the use of alloy with lower melting points than the metals to be fused.
Applications
 Applied in cases where the mechanical properties of the metals are to be preserved (Neto
and Neto 2013).
Limitations
 Strength of the weld is compromised because the weld material may not be effectively
adhesive.
Fusion welding: It involves joining of the metals with molten state of weld filler.
Applications
- In places where large spaces are to be filled.
- Applies to any shape i.e. no external pressure
- Easier welding
Limitations
 Difficult in joining dissimilar metals
 Intense heat affects properties of metals mechanically

The effects of poor welding techniques or unsound weld on the service strength of the joint.
 Faulty technique of welding generally results into porosity which makes joints to be
weak.
Part 4
The metallurgical effects of fusion and non-fusion on these metals.
 Welding of fusion subjected these metals to a lot of heat and there was metallurgical
changes in the pool of the weld particularly shape of these metals.
Chapter 3:
Defects and Failures
Cast aluminium collet for attached to a steel rope immersed in seawater
Causes of failure:
 Neglecting maintenance
 End of span life
Remedial measures to avoid frequent failure:
 Collets usually have a lifespan of about 400-600hrs. This translates into two –three
month. Part of the inspection of the metallic damage will involve bell mounting. The
burrs should be checked for every change in tool. In the cases where the damage is
visible as for this case, the collet should be discarded and replaced with new component.

 During replacement, care must be taken to ensure that there is no entry of flute fadeout
into the collet. This is because they can potentially result into run out and subsequently
tool breakage (Mazumder and Lee 2014).
Stabilized Stainless Steel pipe carried Chlorine at 120oC. Failure occurred in 9 months
Causes of failure
The corrosion of steel pipes in water with chorine contents leads to weakening of the structures.
Such processes of the corrosion are usually regarded to be unusual.
Remedial measures
 Inspection should be done to check for the errors of welding
 Selection of the steel grade should be properly done
 Material fabrication should be done as per the speculated standards.
Cast cam shaft.
Some of the causes of the cam shaft failure will include the following:
 Lobe wear caused by improper lubrication during the processes of installation. This can
be controlled through applications of the lubricants to the drives of the gears.
 Break –ins which are improper (Lu et al.2014). This can be controlled by use of oil that
has motor oil which has break-in additive like the best case of (ZDDP or ZINC camshaft
additive).
 Using new cam with old lifters. This problem can be avoided by discarding the mixed-up
lifters.

Mazak torque test specimen. Aluminium/Zinc alloy
Aluminium/Zinc alloy are usually susceptible to stress corrosion which results into the creation
of lines of weaknesses. When subjected to the test machine, these lines are propagated leading to
the type of the failure which was identified before.
Part of the remedial measures will include proper selection of the materials for the alloy
manufacture and regular inspection to ascertain that the ratios used are within the recommended
limit.
Slave spring for refuse vehicle
Causes of failure: Increase of load on the clutch is likely to cause damage to the springs.
Remedial measure: The springs should be made of stiffer materials which can effectively handle
heavier loads for a long time without necessarily slipping.
Shear pin for forging press
Failure causes: Phenomenon of low cyclic fatigue. This is basically refered to as fatigue
fracture.
Remedial measures: Ensuring prevail or presence of uniform size of the spheroidal cementite
particles of carbide during manufacturing process.
Why one gear of Tin Opener in damaged
The gears of the tin opener usually function to turn the power of the motor into torque. It is this
torque which will turn the tin or can. Large gears are therefore required. The appliance are

therefore provided with large gear systems while on the edge is placement of the shorter gears..
Unbalance of these two parallel forces can lead to breakdown of the teeth (Gibson et al.2014).
Remedial measures: The gears should be checked and replaced in the cases of the broken ones.
Conclusion
The study has effectively highlighted various aspects of the engineering materials and practice of
their applications including fabrication by welding. Various types of welding were found to
possess various merits and demerits which have largely defined their application practices.
Chapter 4
Description of corrosion:
Corrosion refers to a natural process which capable of converting a refined metal into a form
which is more chemically stable such as hydroxide, oxides or sulfides. It refers to the gradual
degradation of metallic materials by electrochemical reactions within a particular environment.
Types of corrosion:
 Pitting corrosion
 Crevice corrosion
 Uniform corrosion
 Galvanic corrosion
 Intergrannular corrosion
 Stress corrosion

Pitting Corrosion:
It has been regarded as one of the destructive methods of corrosion. This is due to the fact that its
prediction is difficult.. It is a form of corrosion which is basically localized. This implies that
either more cathodic point or local anodic point forms a small cell of corrosion with the normal
surface on the surrounding. Upon the initiation of the pit, it will grow into a hole or cavity. The
shape of the cavity or holes will be varying (Gadakh, Shinde and Khemnar 2013).
There is penetration of the pit from the surface vertically downwards. It is caused by a local
damage or break to the local film layer of prevention. Also, it can be caused by non-uniformities
in the structure of the metal itself. It is very dangerous since it is associated with the failure of the
materials.
Figure 12: Types of pitting corrosion (Tan, and Shin 2015)

Uniform Corrosion
It refers to the even attack across the material surface. It is actually the most common type of the
corrosion. It is the most benign as it is relatively easy to judge the extent of attack. Its occurrence
takes place over a larger area.
Figure 13: Uniform corrosion (Tan, and Shin 2015)
Prevention methods for corrosion
Hot-Dip Galvanization:
This method of the prevention of corrosion involves having steel dipped into zinc which has
been molten. The present iron in the steel will react with zinc leading to the creation of a tightly
bonded coating of alloy. This coating will serve as the protective layer.

Figure 14: Hot deep galvanization (Tan, and Shin 2015)
Alloyed steel/Stainless method
Alloyed steel has been identified as one of the effective methods to be used in the prevention of
the corrosion methods. It will involve combination of the properties of various metals so that
addition of resistance and strength can be achieved.

Figure 15: Stainless steel method (Tan, and Shin 2015)
Cathodic protection
In practical, cathodic protection works on the basis of connecting the base metal which is at
brisk preferably steel to a metal regarded as being sacrificial which will corrode at the lieu of the
metal base (Fu et al. 2015). The cathodic provision technique to the steel metal will lead to the
preservation of the metal which is highly active. That metal will act as the anode and hence
provide a free electron. When such kind of the free electrons is provided, there is sacrifice of the
electron by the active metal. The less active metal will thus be prevented from corrosion.
Methods of detecting and inspecting corrosion
i. Profile radiography
ii. Ultrasonic thickness measurement
iii. Insulation removal
iv. Infrared techniques
v. Neutron Backscatter
Stress Corrosion
Stress corrosion takes place when the existence of a material in the environments which is inert
but the process of corrosion is as a result of the stress applied. The application of stress may be
extreme or just residual.
Diagram illustration of stress corrosion

Figure 16: Diagram illustration of stress corrosion (Cho et al.2015)
New methods of corrosion prevention and Old methods comparison.
 Painting coating was used for a long time traditionally for the corrosion protection. The
layer of paints however is never durable and is easily peeled off. The new method
involves the use of sacrificial coating which is more durable and effective.
 Design modification was used traditionally in which the surface which is vulnerable to
the corrosion was not to be exposed to the environments. However, the modern methods
of corrosion involves the use of corrosion inhibitors on those surfaces hence any surface
can be exposed.

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Chapter 3: Defects and Failures
APPENDIX

1.