MSRSAS - Material and surface modification

7/30/2019 MSRSAS - Material and surface modification

1/39

MSRSAS - Postgraduate Engineering and Management Programme - PEMP

i

ASSIGNMENT

Module Code AMT2501

Module NameMaterials and Surface ModificationProcesses

CourseM.Sc [Engg] in Advanced Manufacturing

TechnologyDepartment Mechanical and Manufacturing Engg.

Name of the Student Shanmuga Raja .B

Reg. No BVB0912004

Batch Full-Time 2012.

Module Leader Mr. K.N. Ganapathi

POSTGRADUATEENGIN

EERING

ANDMANAGEMENTPROGRA

MME

(PEMP)

M.S.Ramaiah School of Advanced StudiesPostgraduate Engineering and Management Programmes(PEMP)

#470-P, Peenya Industrial Area, 4th

Phase, Peenya, Bengaluru-560 058

Tel; 080 4906 5555, website: www.msrsas.org


2/39

ii

Declaration SheetStudent Name Shanmuga Raja .B

Reg. No BVB0912004

Course M.Sc [Engg] in AdvancedManufacturing Technology

Batch Full-Time 2012 .

Batch FT 2012

Module Code AMT2501

Module Title Materials and Surface Modification Processes

Module Date 05/11/2012 To 08/12/2012

Module Leader Mr. K.N. Ganapathi

Declaration

The assignment submitted herewith is a result of my own investigations and that I have

conformed to the guidelines against plagiarism as laid out in the PEMP Student

Handbook. All sections of the text and results, which have been obtained from other

sources, are fully referenced. I understand that cheating and plagiarism constitute a

breach of University regulations and will be dealt with accordingly.

Signature of the student Date

Submission date stamp(by ARO)

Signature of the Module Leader and date Signature of Head of the Department and date


3/39


iii

Abstract

____________________________________________________________________________

Fuel crisis lingers in a great turmoil, pushing humans to reach out more the existing practices

and quest for finding genuine natural alternatives. Billions of gallons of fuel are burnt everyday

at the expense of destroying mother earth. Radical initiatives are in need, one such being

advancing the fuel economy, i.e. more mileage with the best functional and safety rationale.

Henry Ford, in his autobiography quoted Fat men cannot run as fast as thin men but, we build

most of our vehicles as though dead-weight fat increased speed, eyeing the fuel consumption.

New design and alternatives are brought to play to improve the fuel economy. The concept of

dead weight is realized and finding alternative lighter substitutes are the talk every auto makers

interest. Aluminium as a substitute to steel; is observed by many auto makers. But, steel is no

longer gone, came up with the best rendition fighting aluminium eye to eye. An insight whether

Aluminium can replace steel in body panel is been discussed.

Pelton wheel, a high efficient impulse water turbine goes under the scanner to determine the

material characteristic of its major parts. The literature is reviewed to understand the basic

function and service conditions of five parts. Material selection, starting with purpose and

objective is not an intuition but, careful assessment of all the service parameters which endorse

high efficiency. Parts are individually broken to analyze its inherent need and clear function.

Material selection is done by justifying based on true properties aligned step by step. The

scenario expedited in the process is systematic addressing the right need.

Pelton wheel Bucket, an aim behind every jet of water to strike, efficiently to take a spin

generating a natural source of power, is assessed to select the best possible material. The

subject is put to careful consideration and analyzed. Cambridge Engineering Selector, a modern

digital software program, delivering all the possible solution of material selection is exploited

to the address the every relative property of Pelton wheel bucket. Process ability and the cost

are the other traits which drives the selection. The whole concurrent stream is necessary to

determine the best available material, and also rate the equal best for alternate considerations.


4/39


iv

Contents____________________________________________________________________________

Declaration Sheet.................................................................................................................. ii

Abstract................................................................................................................................ iii

Contents.................................................................................................................................ivList of Tables..........................................................................................................................v

List of Figures.......................................................................................................................vi

List of Symbols.................................................................................................................... vii

1. Aluminium versus Steel in Car body panel ..................................................................... 11.1 Introduction ................................................................................................................ 1

1.2 Properties requirement of Panel material ................................................................... 1

1.3 Comparison of properties of AHSS and Al alloy for panels ...................................... 2

1.4 Manufacturability and Cost ........................................................................................ 2

1.5 Example for justification ............................................................................................ 3

1.6 Conclusion .................................................................................................................. 3

2. Pelton wheel ....................................................................................................................... 4

2.1 Overview .................................................................................................................... 4

2.2 Parts and Function of Pelton wheel ............................................................................ 5

2.3 Analysis of Material property of Pelton wheel .......................................................... 7

2.4 Material used for parts of Pelton wheel .................................................................... 11

2.5 Conclusion ................................................................................................................ 14

3. Material selection of Pelton wheel Bucket .................................................................... 153.1 Selection Overview .................................................................................................. 15

3.2 Pelton wheel Bucket ................................................................................................. 15

3.3 Selection of Bucket material using CES .................................................................. 17

3.3.1 Functional property ...................................................................................... 18

3.3.2 Process ability ............................................................................................... 20

3.3.3 Cost ............................................................................................................... 22

3.3.4 Resistance to Service environment .............................................................. 22

3.3.5 Material rating ............................................................................................... 24

3.4 Stainless steel characteristic comparison with alternatives ...................................... 24

3.5 Surface treatment ...................................................................................................... 25

3.6 Conclusion ................................................................................................................ 27

Learning Outcome............................................................................................................... 28

References ............................................................................................................................ 29

Bibliography......................................................................................................................... 32


5/39

v

List of Tables

____________________________________________________________________________

Table No. Title of the table Pg.No.Table 1.3 Comparison between AHSS & Aluminium alloy 2

Table 2.3a Material property of Shaft 9Table 2.3b Material property of Casing 9

Table 2.3c Material property of Nozzle 9

Table 2.3d Material property of Spear needle 10

Table 2.3e Material property of Penstock 10

Table 3.3 Requirement for Bucket material selection 17

Table 3.3.4 Material screening 23

Table 3.3.5 Material rating 24

Table 3.4 Steel comparisons 24


6/39


vi

List of Figures

____________________________________________________________________________

Figure No. Title of the figure Pg.No.

Figure 1.2 Car Body panel 1

Figure 1.3 Strength versus Elongation chart 2Figure 1.5 AHSS usage trend 3

Figure 2.1a Schematic of Hydropower generation 4

Figure 2.1b Assembly of Pelton wheel 4

Figure 2.2a Construction of Pelton wheel 5

Figure 2.2b Pelton wheel Shaft 6

Figure 2.2c Runner with Bucket 6

Figure 2.2d Water flow simulation 7

Figure 2.2e Multi Nozzle arrangement 7

Figure 2.2f Spear needle arrangement 8

Figure 2.2g Penstock 8

Figure 2.3 Spear needle cavitation 10

Figure 2.4a Selection of material Shaft-Initial 11

Figure 2.4b Selection of material Shaft-Final 12

Figure 2.4c Selection of material Casing 12

Figure 2.4d Selection of material Nozzle and Spear-Initial 13

Figure 2.4e Selection of material Nozzle and Spear-Final 13

Figure 2.4f Selection of Penstock 14

Figure 3.2a Bucket 16

Figure 3.2b Water displacement in Bucket 16

Figure 3.3.1a Hardness versus Youngs modulus 18

Figure 3.3.1b Fracture toughness 19Figure 3.3.1c Fatigue strength 20

Figure 3.3.2a Formability versus Machinability 21

Figure 3.3.2b Weldability 21

Figure 3.3.3 Comparison of Cost price 22

Figure 3.3.4 Durability conditions 23

Figure 3.4 Surface treatment 25


7/39


vii

List of Symbols____________________________________________________________________________

Symbol Description Units

AHSS Advanced High Strength SteelAl Aluminum

CES Cambridge Engineering Selector

ULSAB Ultra Light Steel Auto Body


8/39


1

PART-A

CHAPTER 1

1. Aluminium versus Steel in Car body panel1.1 Introduction:

The world is said to run on wheels, the same is true. Automobiles have become an intrinsic part of

day to day life from mass transport to personal transport, from need to luxury. On the practical

stake, huge amount of fuel is burnt at the expense of deteriorating the environment. With no other

alternatives government bodies are striving to regulate the raise of fuel economy standards. Fuel

economy can be enriched by reducing the weight of the car in three ways (Stadolsky et al. 1995: 3)

by reducing its size, optimizing design to minimum weight and replacing heavier material with the

lighter one. Steel, being a best known engineering material from ages, where the vast background

knowledge acquired, is molded to suit any application cost effectively. Modern materials like

aluminium can be a strong counterpart offering better characteristic over less weight is merely a

better substitute. Strength to weight ratio (performance model) alone is not sufficient to satisfy real

value but, also ever growing need for high safety standards, the cost incurred and ability to repair

or rework . Steel industry also catching the race with their own rendition through Ultra high

strength steel, lowering weight and escalating strength as well as formability than traditional steels.

1.2 Properties requirement of panel material:

Car body panel used are as shown in Figure 1.2, it forms the exterior profile body of the car. The

panel material i.e. the closures, accounts to approx. 5% of the total body mass (Carlson et al. 2010).

Figure 1.2: Car body panel

(Shop at India n.d.,)

The body panels need to have certain properties like, less weight, corrosion resistance, since it is

exposed to the environment, Strength and stiffness to absorb and withstand energy in crashes, good


9/39


2

formability and manufacturability per the requirement, dent resistance and rework ability,

sustainability, Class-A surface quality and cost.

1.3 Comparison of properties of AHSS and Al alloy for panels:The strength to elongation relationship of AHSS and Al alloy is shown in Figure 1.3

Figure 1.3: Strength versus elongation chart(Billur, Mao and Altan 2012: 15)

The general property comparison between AHSS (First generation) and Aluminum alloy is given in

Table 1.3

AHSS Al alloy

High strength and low formability low strength and low formability

High spring back moderate spring back

High stiffness and dent resistance Low stiffness and dent resistance

Low strength to weight ratio High strength to weight ratio

low corrosion resistance high corrosion resistance

Low weight due to lesser gauge

thickness because of strengthLow weight by density

high wear resistance low wear resistance

high crash worthiness low crash worthiness

Low rework / repair ability Moderate rework / repair ability

Inconsistent material property Consistent material property

Table 1.3: Comparison between AHSS and Aluminum alloy

1.4 Manufacturability and Cost:

AHSS (Billur, Mao and Altan 2012):

Forming requires strong die material and coating. Due to high strength of steel more loading

capacity of press required, which can be tweaked with the current infrastructure available.

Springback is an issue with AHSS, holding on engage and re-striking with servo drive presses

enhances cold forming. Hot forming can be used as a substitute, no issues with welding. Repairing


10/39


3

a strain hardened AHSS is a tedious activity may result in fracture. The cost of material as well as

the processing is less, utilizing the same infrastructure built for conventional steel processing.

Aluminum alloy (Sever et al. 2012):Formability of aluminium is less compared to that of steel. Warm forming and hydro forming can

be employed, which uses special setup and insulation as heat is involved. Lubricants are used to

reduce friction. Welding flexibility is not as steel, but some of the aluminium grades can be welded

easily. The cost of aluminium is high compared to steel, but one of the most sustainable materials.

Manufacturing needs special setup, capital cost is high, only suitable for low volume production.

1.5 Example for justification:

Honda, was the first to launch alternate material car, however the latest version is with AHSS

intense. BMW launched aluminium version with 5 series, but recently switched to steel (Geck

2010). Price of car is a major driving concern, auto industry is rather cost oriented than the

performance. Business target aim primarily on manufacturing and cost. Though high end cars rely

on performance is produced in low volumes because of less demand. High volume production still

sticks on to steel, with an already built vast infrastructure, by replacing with AHSS (Hall 2008).

There will be a growth in AHSS usage in future years as shown in Figure 1.5 a new benchmarking

is going to be achieved through Ultra Light Steel Auto Body (ULSAB) with no additional cost but

with enhanced safety parameters with less weight (World auto steel n.d.,)

Figure 1.5: AHSS usage trend

(Hall 2008: 28)

1.6 Conclusion:

Aluminium can be a best substitute to steel, but the ongoing development in steel like ULSAB

makes much more sense utilizing the current capabilities to its fullest. Considering cost barrier as a

primary objective and characteristics next, it can be assessed as aluminum can replace steel only toa certain extent. But steel is competitively building its edge over ages to prove it is very capable.


11/39


4

PART-B

CHAPTER 2

________________________________________________________________________________

2. Pelton wheel2.1 Overview:

The Pelton wheel, also known as Pelton turbine is a tangential flow impulse turbine; it is more

efficient than any other impulse turbine. The pressure energy of the water is converted into kinetic

energy (Bansal 2005: 851), when flown through a nozzle causing pressure amplification, hits the

bucket mounted on a shaft causing rotation of the runner. It is named after an American engineer

Lester Allan Pelton, who improvised the water wheel by splitting incoming jet provisioned through

bucket making the wheel to run faster (Wikipedia 2012a). Pelton wheel is used in hydro-electric

plants where high heads of water with low discharge. Pelton can be horizontally mounted or

vertically designated with the shaft axis, single jet or multi-jet pelton wheel are available. Figure

2.1a shows the logical technology behind power generation using turbine, Figure 2.1b shows the

assembly of pelton wheel turbine.

Figure 2.1a: Schematic of hydropower generation

(Current generation 2011)

Figure 2.1b: Assembly of Pelton wheel(Wikipedia 2012b)


12/39


5

2.2 Parts and function of Pelton wheel:

Construction of a pelton wheel hosts different parts offering unique function to drive the power.

Figure 2.2a show the elements of construction.

Figure 2.2a: Construction of pelton wheel

(Rajput 2005: 358)

Pelton wheel consists of following parts and the function of the highlighted parts will be discussed. Shaft Runner with buckets Casing Nozzle Spear needle Penstock

Shaft:The shaft is a rotating member keyed to the runner assembly. The shaft is coupled to the generator,

power is determined from the rotation of the shaft. The circular and cylindrical run-out of the shat is

a substantial criterion for its efficiency. Guide bearing block houses the shaft to maintain an unison

rotation throughout the entire span. Figure 2.2b shows the picture of the shaft mounted with runner

along on the bearing housing.


13/39


6

Figure 2.2b: Pelton wheel shaft(Fuchan industry n.d.,)

Runner assembly:

Runner is a circular wheel which is mounted on the shaft and keyed in. It consist number of

hemispherical buckets, evenly spaced on its periphery. The buckets can be welded with the runner

or fastened as an attachment or can be cast as an whole assembly. The bucket has a vane provision

known as a splitter which breaks the incoming water gliding over the cup and departing. Two or

more runner can be mounted on the shaft. Figure 2.2c shows runner assembly.

Figure 2.2c: Runner with bucket

(Bright hub engineering 2012)

Casing:

Casing is not associated with any hydraulic function. It provides and enclosure to safeguard the

turbulent water dragged out from the bucket. It act as a guide for water to discharge from to the tail

race (Bansal 2005: 852). Figure 2.2d shows the fluid flow simulation within the casing.


14/39


7

Figure 2.2d: water flow simulation

(HAP 2011: 11)

Nozzle:

Nozzle is a member used to direct the water discharge to the buckets. A convergent nozzle is used

to build the pressure of the incoming water and direct over the bucket making it to rotate. A pelton

wheel turbine can be built with a single or a set of nozzle depending on the head available to

harness maximum potential. Figure 2.2e shows a multi nozzle arrangement

Figure 2.2e: Multi nozzle arrangement

(Renew hydro n.d.,)

Spear needle:

Is a conical device used to control and direct a sharp flow of the water through the nozzle orifice.

The velocity of the water impinging on the bucket is controlled by blocking and opening the spear

needle. A handle can be rotated to push-in or push-out based on the requirement. Figure 2.2f shows

the spear needle engage and dis-engage.


15/39


8

Figure 2.2f: Spear needle arrangement

(Subbarao n.d.,: 18)

Penstock:

Penstock is a tubular duct which supplies water from the storage source into the nozzle via a

distributor manifold. It can have gates to restrict the water flow. It is like a tube descending from

storage source to the nozzle, the cross section can be uniform or divergent to proliferate the velocity

of the flow. Figure 2.2g shows the penstock application in real site.

Figure 2.2g: Penstock

(Qurren 2011)


16/39


9

2.3 Analysis of material property of Pelton wheel parts:

The materials for the parts of pelton wheel are selected subjective to analysis based on the property

which it need to wok i.e. the environment and to award the best possible efficiency. The material

characteristics are discussed selecting each component and their requirement.Shaft:

Shaft is a primary member, only whose rotation purely determines the output efficiency. It needs to

bear some of the vital properties to ensure that. The property requirements based on the working

analysis of shaft is shown in Table 2.3a

Material property Requirement

Stiffness to withstand deformation, having high elastic modulus

Bending strength to withstand the weight of the runner assembly mount

corrosion resistance to resist fresh, salt and soil water conditions

Fatigue resistance to withstand cyclic loads of combined torsional and bending stresses

wear resistance wear causing slippages and run-out of shaft, tribological concerns

low co-efficient of friction to maximize the output efficiency

Surface finish to enhance lubrication

Table 2.3a: Material property of Shaft

Casing:

The rigid member, though need to perform some of the functions for a whole approach. The

property which a casing has to offer is shown in Table 2.3b


Dampening to reduce vibration

Impact resistance to withstand splashes from bucket

corrosion resistance to withstand fresh, salt and soil water conditions

Surface finish to guide water to tail race causing no counter impact to bucket

Table 2.3b: Material property of Casing

Nozzle:Nozzle an important jet guiding member has to withstand some of the impact caused by the jet with

high velocity. Table 2.3c shows the material requirement.


Corrosion resistance to withstand fresh, salt and soil water conditions

wear resistance due to the high velocities of water leading to worn surface

surface finish guide water smoothly and impinge directly on the splitter

Impact resistance to withstand back pressure from jet splashing bucket

Table 2.3c: Material property of Nozzle


17/39


10

Spear Needle:

A conical needle, is an actuation member to control the flow of water jet. Table 2.3d shows the

property requirement of the Spear needle.

Material property RequirementCorrosion

resistance

to withstand fresh, salt and soil water conditions preventing

cavitation

Wear and abrasion

resistance

due to the high velocities of water leading to edge crack, silt

erosion and uneven discharges,

surface finish guide water smoothly as a concentrated jet

Impact resistance to withstand the impact surges from rotating bucket

Table 2.3d: Material property of Spear Needle

An example of eroded spear is shown in Figure 2.3, where the tip has lead to cavitation, which is

going to lead to uneven jet discharge.

Figure 2.3: Spear Needle corrosion

(HAP 2011: 12)

Penstock:

Penstock is a hollow tube which connects the access of water from storage source to nozzle via a

distributor manifold. The length of these may follow from several meters. Table 2.3e shows the

material properties expected by these penstock.


Corrosion resistance to withstand fresh, salt and soil water conditions

fracture toughness to withstand internal pressure (hoop stress) developed and crack

elastic modulus able to draw to form tubular sections followed by welding

Table 2.3e: Material property of Penstock


18/39


11

All the parts coming in contact with turbulent water faces cavitation due to the suspended soil

particle abrading the surface of the part. This is a major concern with water turbines.

2.4 Material used for parts of Pelton wheel:As discussed in section 2.3, the task can be put forth in selection of material to the intended use.

Material selection can be done by Data hand books or Selection software.

Shaft:

Cambridge Engineering Selector (CES), can be used to select the general material responsive to the

cited requirement. Following steps are followed to assess the suitable method.

CES, Lever -2 is chosen for selection. Material can be directly selected through option SELECT, instead of searching. Edu level 2: Materials with durability properties is defined. Limit is set with excelling in fresh, salt and soil water resistance. A Graph, is set considering fracture toughness versus fatigue strength, top 14 materials

are selected as shown in Figure 2.4a

Once again a Graph is set between the hardness and the cost (since INR was not availableUSD is used) as shown in Figure 2.4b

Material selected are Bronze or Stainless steel for the application.

Fatigue strength at 10^7 cycles (MPa)1 10 100 1000

Fracturetoughness(MPa.m

^1/2)

0.01

0.1

1

10

100

Stainless steel

Nickel-chromium alloys

Bronze

Figure 2.4a: Selection of material shaft-initial


19/39


12

Price (USD/kg)0.1 1 10 100

Hardness-Vickers(HV)

0.001

0.01

0.1

1

10

100

1000

Bronze Stainless steel

Figure 2.4b: Selection of material shaft-final

Casing:

Literature will be handy for selection. Since, dampening is the primary criteria; Gray Cast Iron can

be used. The part could be simply cast as functionally casing doesnt add any value.

CES can also be put to use to determine the right material.

Limit is set as acceptable resistance to water. Process, Surface coating and painting is added to resist the impact of jet. Graph is plotted with castability against cost. Gray Cast Iron and SG Iron hold the top ranks as shown in Figure 2.4c

Price (USD/kg)1 10 100

Castability

1

2

3

4

5

Cast iron, gray

Cast iron, ductile (nodular)

Figure 2.4c: Selection of material Casing


20/39


13

Nozzle and Spear Needle:

These two parts more or less do hold the same working characteristics. So, the result can be

assessed as consolidate.

Limit is set for excelling fresh, salt and soil water condition. Tree is set with collection of Metals, Non-metals and ceramics, with surface treatment. Graph is plotted as Hardness versus Fracture toughness, top 14 materials are selected

bidding the performance as shown in Figure 2.4d

Graph is plotted to derive the inexpensive material. Bronze, Stainless steel and Siliconcarbide are the material selected as shown in Figure 2.4e TiN coating can be applied to

invoke wear resistance.

Fracture toughness (MPa.m^1/2)0.01 0.1 1 10 100

Hardness-Vickers(HV)

0.001

0.01

0.1

1

10

100

1000

Nickel-based superalloys

Stainless steel

Boron carbide

Silicon carbide

Bronze

Figure 2.4d: Selection of material Nozzle and Spear-initial

Price(USD/kg)

0.1

1

10

100

Bronze

Stainless steel

Silicon carbide

Figure 2.4e: Selection of material Nozzle and Spear-Final


21/39


14

Penstock:

Penstock, is an external part functioning to carry the water from source to destination. Earlier days

steel pipes were used, later galvanized iron pipe. Other possibilities are explored with CES.

Limit is set excelling water conditions fresh, salt and soil. Tree is set compiling joining and shaping process. Graph is plotted between fracture toughness and hardness. Graph is plotted again to derive the economical material. Concrete, PVC and Stainless

steel can play as an optimal choice as shown in Figure 2.4f

Price(USD/kg)

0.1

1

10

100

Concrete

Sandstone

SlatePolyvinylchloride (tpPV C)

Aluminum nitride

Polyetheretherketone (PEEK)

Titanium alloys

Polytetrafluoroethylene (Teflon, PTFE)Nickel

Polyoxymethylene (Acetal, POM)

Stainless stee l

Figure 2.4f: Selection of material Penstock

2.5 Conclusion:

The major five parts of Pelton wheel are selected. Shaft, Casing, Spear needle, Nozzle and

penstock, whose properties are ascertained, respected to its functionality. CES is used to

determine the material as,

Shaft - Stainless steel Casing - Gray cast iron Spear - Bronze, Stainless steel, Titanium carbide coating Nozzle - Bronze, Stainless steel, Titanium carbide coating Penstock - Concrete, PVC for medium head, Steel for low head


22/39


23/39


16

Figure 3.2a: Bucket

(Cink n.d.,)

Figure 3.2b: Water displacement in bucket(Kennedy 1903)

Rotation of the shaft is totally relied on the bucket design and the jet flow. The design of the bucket

to deliver maximum efficiency is the key criteria. Pelton wheel bucket is subject to lot of stress and

other operating obstacles. Silt erosion and cavitation is a major threat posed by the bucket. The

water flowing in to the turbine may contain sand and minerals which abrades the surface

microscopically leading to loss of efficiency.


24/39


17

3.3 Selection of Bucket material using CES:

Cambridge Engineering selector (CES) is made use to select the material for Pelton wheel Bucket,

requirements of the selection need to be framed, whose input can offer a whole lot of selection from

diverse range of data. The general characteristic which substantiates bucket material selection arediscussed in Table 3.3

Characteristic Requirement

Function

Corrosion

resistance to withstand fresh and salt water conditions preventing rusting

Stiffness

to withstand deformation under consistent pressure, high Youngs

modulus

Wear resistance to withstand slit erosion caused by sand and mineral mixtures

Fatigue resistance to withstand the cyclic load acting on the cups

Fracture toughness to resist crack propagationImpact resistance to withstand shock loads for high velocity water jet

Surface finish

to guide the water along with distorting the turbulence, low co-ef of

friction

Process Primary process able to cast or forge

Secondary process able to machine, grind, weld

Surface treatment to withstand tribological concern for the water sample mixture

Cost

Material cost cost of material based on functional requirement

Manufacturing cost cost of processing to exhibit best service condition

Servicing cost cost incurrent on servicing as per the cycles of operation

Table 3.3: Requirements for bucket material selection

Cambridge Engineering Selector (CES), is used to find the solution for Pelton wheel Bucket.

Corrosion resistance is a surface property depending on serviceable environment. So as discussed in

Section 3.1 Selection Overview, this service or surface property can be analyzed after ideal material

selection based after function, process and cost since, surface treatment can add value to the

material performance on subsequent stages.

As expressed in Section 3.1 Selection Overview, step involved in Initial screening is with,

Functional property Process ability Cost Reliability (Since, dependent on practical usage cycle; not considered here) Resistance to service environment


25/39


18

3.3.1 Functional property:

Based on the material characteristic, CES is maneuvered to serve the need. Following are detailed

steps associated with snapshot of CES Edupack 2009 program to input the design data.

Step-1:

The primary functional criteria of the Pelton wheel Bucket is its stiffness, so a material with higher

Youngs modulus to be selected. Stiffness can be related with the wear resistance property i.e. high

hardness value. Italicized words are the options used in CES

Level 2 is selected for finding, 98 material are available

Select tab is used instead of Browse or Search Select from:Edu level 2 Materials with durability properties Graph is selected to plot mechanical properties, Hardness-Vickers (x-axis) versus

Youngs modulus (y-axis)

Ashby chart lists 89 materials out of 98 A Box selection is used to select top 40 results Figure 3.3.1a shows the selection, grayed out results are omitted.

Figure 3.3.1a: Hardness versus Youngs modulus


26/39


19

Step -2:

Fracture strength is a vital criterion for the effective performance of Pelton Bucket, a comparison of

this property is done in the same file.

Graph is selected to plot the mechanical property, Fracture toughness out from selected40 materials

A Box selection is used to select top 30 results Figure 3.3.1b shows the comparison of Fracture toughness.

Figure 3.3.1b: Fracture toughness

Step -3:

The next property of Pelton Bucket is Fatigue resistance, as the rotating cups are subjected to some

cyclic load, the residual stress induced may lead to fracture. So the material is analyzed for its

performance to withstand these loads.

Graph is selected to plot the mechanical property, Fatigue strength out from selected 30materials

A Box selection is used to select top 20 results Figure 3.3.1c shows the comparison of Fatigue toughness. Fracture and fatigue strength

could have been plotted as a whole, but due the dominant inherent characteristic the

functional properties are organized and concluded.


27/39


20

Figure 3.3.1c: Fatigue strength

3.3.2 Process ability:

Only the functional attributes alone cannot be judged for selection, are the initial design functions

are flexible for producing, need to be looked upon. Forging of Bucket are chosen than casting

because of homogeneity, machining and welding capabilities need to be explored.

Graph is selected to plot the process ability, Formability (x-axis) versus Machinability(y-axis) out from selected 20 materials

A Box selection is used to select top 12 results Figure 3.3.2a shows the comparison of Formability versus Machinability.

Then one of the most important process to assemble runner and Bucket, which is welding is applied

Graph is selected to plot the process ability, Weldability The same top 12 materials are compared Figure 3.3.2b shows the comparison of Weldability.


28/39


21

Figure 3.3.2a: Formability versus Machinability

Figure 3.3.2b: Weldability


29/39


22

3.3.3 Cost:

The cost of the material and processing is a driving factor for its applicability. Optimum

performance model with lower cost is the best practice in interest of any business.

The selected 12 materials are compared for its cost Graph is selected to plot the cost price per kg, USD is used instead of unavailability of

INR cost unit.

Figure 3.3.3 shows the comparison of Cost price.

Figure 3.3.3: Comparison of cost price

3.3.4 Resistance to service environment:

The selected material should be able to withstand the operating environment. For a Pelton wheel

Bucket, it is of prime importance that it should not corrode with fresh, salt, silt water conditions.

The necessary surface treatment can be carried to inhibit corrosion, though it is advisable to have a

view whether materials directly suit the requirement. Following conditions are applied:

Limit is applied to select the durability function with fresh, salt, soils and clay to beexcellent.

Figure 3.3.4 shows 8 materials listed for the purpose


30/39


23

Figure3.3.4: Durability conditions

Narrowed down by multiple stages, 8 materials are listed finally as shown in Table 3.3.4

Function Process Environment

Alumina Brass Brass

Boron carbide Bronze Bronze

Brass Commercially pure titanium Commercially pure titanium

Bronze High carbon steel Nickel

Cast iron, ductile (nodular) Low alloy steel Nickel-based superalloys

Commercially pure titanium Low carbon steel Nickel-chromium alloys

High carbon steel Medium carbon steel Stainless steel

Low alloy steel Nickel Titanium alloys

Low carbon steel Nickel-based superalloys

Medium carbon steel Nickel-chromium alloys

Nickel Stainless steel

Nickel-based superalloys Titanium alloys

Nickel-chromium alloys

Silicon carbide

Silicon nitride

Stainless steel

Titanium alloys

Tungsten alloys

Tungsten carbides

Zirconia

Table 3.3.4: Material screening


31/39


24

3.3.5 Material rating:

The selected materials are rated against their feature to become the Bucket material. The basis of

rating is its functional, processability, cost and serviceability aspect. A Five scale rating is used for

justifying individual judgment without biasing. Table 3.3.5 shows the rating

Material

Function Process

cost TotalStiffness

vs

hardness

Fracture

toughness

Fatigue

strength

Forming

vs

Machining

Welding

Brass 3 2 2 5 4 5 21

Bronze 2 2 2 4 4 5 19

Commercially pure titanium 2 2 3 1 4 2 14

Nickel 4 4 3 3 4 3 21

Nickel-based superalloys 5 4 5 3 4 3 24

Nickel-chromium alloys 4 4 3 3 4 3 21

Stainless steel 5 5 4 2 5 4 25

Titanium alloys 4 3 4 1 4 2 18

Table 3.3.5: Material rating

Stainless steel is the best material as a whole package for Pelton wheel Bucket scoring 25 out of

30 followed by Nickel.

3.4 Stainless steel characteristics comparison with alternatives:

Stainless clearly won the whole requirement. But, other steels too were in a tight competitive

comparison until cost and losing just because of its service environment i.e. Corrosion resistance.

Since, surface treatment can get the other steels performing the same action; a comparison is carried

out excluding surface condition. Table 3.4 shows the comparison of stainless steel with other steels.

Properties

Low carbon

steel

Medium carbon

steel

High carbon

steel

Low alloy

steel

stainless

steel

Youngs modulus (GPa) 200

215 200

216 200

215 205

217 189

210Hardness (HV) 108 173 122 565 160 650 140 693 130 570

Fracture toughness

(MPa.m^1/2) 41 82 12 92 27 92 14 200 62 150

Fatigue strength at 10^7

cycles (Mpa) 203 293 229 600 281 606 248 700 175 753

Formability rating 4 5 4 5 4 5 3 4 2 3

Machinability rating 3 4 3 4 3 4 3 4 2 3

Weldability rating 5 5 5 5 5

Cost (USD /Kg) 0.634 - 0.698 0.671 - 0.738 0.723 - 0.796

0.806 -

0.887 6.52 - 7.17Table 3.4 Steel comparisons (from CES datasheet)


32/39


25

It is notices that, Low alloy steel is the best competitor in every regard to Stainless steel. Having

all the fair attributes better than that of Stainless steel, it can be concluded that Low alloy steel is

the perfect material for Pelton wheel Bucket, with surface properties improved with coating.

3.5 Surface treatment:

Low alloy steel is susceptible to corrosion, as it needs to perform well with the aqueous condition a

surface treatment method is chosen to give the material the sustainability with following critical

touchstones:

Corrosion resistance (resist oxidation) Wear resistance (resist silt abrasion)

CES, is used to identify the surface treatments applicable to improve material characteristics, thesteps are as followed:

Level3 is selected of CES Edupack 2009 Select from, Processes universeSurface treatment TREE is used to locate the material Low alloy steel fromMaterial Universe. Limit is set to define the function of treatment, for corrosion and erosion resistance, with

economic attributes: labor intensity, equipment and tooling cost as shown in Figure 3.4

Figure 3.4a: Surface treatment


33/39


26

Three surface modification process are listed based on functional and economic attributes

Electroless (auto catalyst) process Flame spraying Hot-dip coating

Flame spraying is the best method being able to apply over large surface area with less overall cost.

Flame spraying is a overlay coating technique done by arc wire thermal spraying, plasma arc

spraying and powder flame spraying. The process parameters mainly depend on (Thapa et al. n.d.,)

Coating material property- Chemical composition- Melting point-

Morphology- Particle size distribution- Shape

Spraying process control- Flame temperature- Gas pressure- Powder flow rate- Geometry of nozzle- Spray distance- Surface preparation and substrate

Case study conducted on the hydro erosion resistance of Kalingdaki hydropower plant is vital to

justify the sustainability rendered by High Velocity Oxygen Fuel (HVOF) flame spraying. The

coating can be applied to stainless as well as low alloy steel. The tungsten carbide ceramic coating

shows better resistance to sediment laden water erosion. High abrasion resistance and increased

fatigue resistance is offered by tungsten carbide coating (Alstom 2012). Vacuum plasma spraying

has better properties than atmospheric spray (Kumar, Sapra, Bhandari 2011) Tungsten carbide and

Cobalt chromium have an edge than any other coating.


34/39


27

3.6 Conclusion:

Stainless steel is the best material for Pelton wheel bucket based on performance, Low alloy steel is

considered to be the cost effective substitute whose surface characteristics improvement makes a

close competitor to stainless steel. Flame hardening is the surface treatment best suited forcorrosion and abrasion resistance of the material. Tungsten carbide and Cobalt chromium raises the

standard of performance of these materials against sediment laden particles.


35/39


28

Learning Outcome________________________________________________________________________________

Aluminium is replacing the Steel entirely in car body panel; a scintillating topic put forth. As

simple the issue looks, more deceiving it is. Every piece of literature gives it own right. The topic

aided to realize the circumstance to select the best material aiming a global cause and also

understand the limiting factors, why it is hard for a switchover. Material property has an intrinsic

value, alone which cant be justified unless related to the cost. The rationale behind using the

performance model and cost model is learnt. Either way the benefit can be reaped, by Improvisation

or substitution. Business excellence is driving the research; every need of customer is expected to

be the best but at no additional expense, a tricky part. Opinion should not be biased, but the

numbers should speak the fact, it is understood.

Perplexed that, what I learn from Part-B? As it speaks the material selection of major Pelton wheel

parts, I gained the clarity behind the notion. Every assessment should start from the mechanism

behind it. Pelton wheel is a whole mechanism being simple, the major parts contributes to its

overall functioning. The art of initial screening, without any technical input is made known with

this. The analysis can be purely judgmental if the right properties are assessed. The process of

listing the characteristic based on function is made known. I was able to relate material science andengineering beholding the classification.

Pelton wheel Bucket selection is made easy only with knowing the function behind, which was

dealt in Part-B. Though Part-B was an overview classification and selection. Part-C was a discrete

initiative to select the material with much more precision by increasing the degree of input. CES is

a thoughtful medium, the screening, comparison and selection is made available saving enormous

time. The problem, helped to find a concise systematic way for solution. How best a material could

be explored is learnt. Defining the performance index to suit the requirement is understood.

Assisted to gain the confidence in selecting material for any real time situation. The mode to

distinguish and apply consideration in various method is understood.


36/39


29

References________________________________________________________________________________

Alstom (2012) Pelton hydro turbines [online] available from

[06 December 2012]

Bansal, R.k. (2005) Fluid mechanics and Hydraulic machines [online] 9th edn.

Delhi: Laxmi publications available from

[03 December 2012]

Billur, Erren. Mao, Tingting. Dr, Altan, Taylan. (2012) Forming of AHSS and Al Alloys,

Part IAdvanced High Strength Steels [online] available from

< http://nsm.eng.ohio-state.edu/cpf/Forming_of_AHSS_and_Al_Alloys.pdf>

[30 November 2012]

Brighthub engineering (2012)Hydraulic Turbines: The Pelton Turbine [online] available from

[30 December 2012]

Carlson, Blair. Krajewski, Paul. Sachdev, Anil. Schroth, Jim. Sigler, David. (2012)

Challenges and opportunities relative to increased usage of Aluminum within the

Automotive industry [online] available from [30 November 2012]

Cink (n.d.,) Pelton [online] available from

[05 December 2012]

Current generation (2012)Information [online] available from

[30 December 2012]

Farag, M. Mahmood. Kutz, Myer (ed.) (2002)Handbook of Materials Selection.

New York: John Wiley & Sons, Inc.,

Fuchan industry (n.d.,) Products [online] available from

< http://www.fuchunind.com/product_show.asp?bid=&tid=130&id=4>

[03 December 2012]
http://www.alstom.com/power/renewables/hydro/hydro-turbines/pelton-turbines/http://books.google.co.in/books?id=nCnifcUdNp4Chttp://nsm.eng.ohio-state.edu/cpf/Forming_of_AHSS_and_Al_Alloys.pdfhttp://www.brighthubengineering.com/fluid-mechanics-hydraulics/26777-hydraulic-turbines-the-pelton-turbine/http://www.brighthubengineering.com/fluid-mechanics-hydraulics/26777-hydraulic-turbines-the-pelton-turbine/http://www.tms.org/meetings/annual-10/PDFs/presentations/verbrugge.pdfhttp://www.tms.org/meetings/annual-10/PDFs/presentations/verbrugge.pdfhttp://www.cink-hydro-energy.com/galerie/turbiny/galerie/pelton/pel8_big.jpghttp://currentgeneration.co.nz/INFORMATION/ABOUT+RENEWABLE+ENERGY/MICRO-HRDRO+WATER+TURBINE.htmlhttp://currentgeneration.co.nz/INFORMATION/ABOUT+RENEWABLE+ENERGY/MICRO-HRDRO+WATER+TURBINE.htmlhttp://www.fuchunind.com/product_show.asp?bid=&tid=130&id=4http://www.fuchunind.com/product_show.asp?bid=&tid=130&id=4http://currentgeneration.co.nz/INFORMATION/ABOUT+RENEWABLE+ENERGY/MICRO-HRDRO+WATER+TURBINE.htmlhttp://currentgeneration.co.nz/INFORMATION/ABOUT+RENEWABLE+ENERGY/MICRO-HRDRO+WATER+TURBINE.htmlhttp://currentgeneration.co.nz/INFORMATION/ABOUT+RENEWABLE+ENERGY/MICRO-HRDRO+WATER+TURBINE.htmlhttp://www.cink-hydro-energy.com/galerie/turbiny/galerie/pelton/pel8_big.jpghttp://www.tms.org/meetings/annual-10/PDFs/presentations/verbrugge.pdfhttp://www.tms.org/meetings/annual-10/PDFs/presentations/verbrugge.pdfhttp://www.brighthubengineering.com/fluid-mechanics-hydraulics/26777-hydraulic-turbines-the-pelton-turbine/http://www.brighthubengineering.com/fluid-mechanics-hydraulics/26777-hydraulic-turbines-the-pelton-turbine/http://nsm.eng.ohio-state.edu/cpf/Forming_of_AHSS_and_Al_Alloys.pdfhttp://books.google.co.in/books?id=nCnifcUdNp4Chttp://www.alstom.com/power/renewables/hydro/hydro-turbines/pelton-turbines/


37/39


30

Geck, Paul. (2010)Advanced High-Strength Steels Add Strength and Ductility to Vehicle Design

[online] available from < http://machinedesign.com/article/advanced-high-strength-steels-

add-strength-and-ductility-to-vehicle-design-0503> [01 December 2012]

Hall, N. Jody. (2008) 50 year Perspective of Automotive Engineering Body Materials and an

Analysis of the Future [online] available from

[01 December 2012]

HAP (2011)Best practice catalog : Pelton turbine [online] available from

< http://hydropower.ornl.gov/HAP/BestPracticeCatComp.pdf> [03 December 2012]

Kennedy, Rankin (1903) Pelton wheel water turbine, nozzle and bucket (Rankin Kennedy,

Electrical Installations, Vol III, 1903) [online] available from

[05 December 2012]

Kumar, Adarsh. Sapra, Pawan kumar. Bhandari, Sanjay. (2011)A Review paper on slurry erosion

of Plasma and Flame thermal sprayed coatings [online] available from

[06 December 2012]

Qurren (2011) Kokuto III power station penstock[online] available from

[04 December 2012]

Rajput, R.K (2005)Elements of Mechanical Engineering [online] Delhi: Laxmi publications

available from

[03 December 2012]

Renew hydro (n.d.,) Pelton wheel [online] available from

[03 December 2012]

Sever, Nimit kardes. Balachenderan, Madhumitha. Billur, Erren. Dr, Altan, Taylan. (2012)

Forming of Aluminum Alloy Sheets for Automotive Applications [online] available from

< http://nsmwww.eng.ohio-state.edu/CPF_Al_forming.pdf> [01 December 2012]
http://machinedesign.com/article/advanced-high-strength-steels-add-strength-and-ductility-to-vehicle-design-0503http://machinedesign.com/article/advanced-high-strength-steels-add-strength-and-ductility-to-vehicle-design-0503http://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://hydropower.ornl.gov/HAP/BestPracticeCatComp.pdfhttp://commons.wikimedia.org/wiki/File:Pelton_wheel_water_turbine,_nozzle_and_bucket_%28Rankin_Kennedy,_Electrical_Installations,_Vol_III,_1903%29.jpghttp://commons.wikimedia.org/wiki/File:Pelton_wheel_water_turbine,_nozzle_and_bucket_%28Rankin_Kennedy,_Electrical_Installations,_Vol_III,_1903%29.jpghttp://ptuconferences.com/digitallibrary/aftmme2011/62.pdfhttp://commons.wikimedia.org/wiki/File:Kokuto_III_power_station_penstock.jpg%23filehttp://books.google.co.in/books?id=CtT0fzwkMvUC&dq=pelton+wheel&source=gbs_navlinks_shttp://books.google.co.in/books?id=CtT0fzwkMvUC&dq=pelton+wheel&source=gbs_navlinks_shttp://www.renewhydro.com/index3B.htmlhttp://nsmwww.eng.ohio-state.edu/CPF_Al_forming.pdfhttp://nsmwww.eng.ohio-state.edu/CPF_Al_forming.pdfhttp://www.renewhydro.com/index3B.htmlhttp://books.google.co.in/books?id=CtT0fzwkMvUC&dq=pelton+wheel&source=gbs_navlinks_shttp://books.google.co.in/books?id=CtT0fzwkMvUC&dq=pelton+wheel&source=gbs_navlinks_shttp://books.google.co.in/books?id=CtT0fzwkMvUC&dq=pelton+wheel&source=gbs_navlinks_shttp://commons.wikimedia.org/wiki/File:Kokuto_III_power_station_penstock.jpg%23filehttp://ptuconferences.com/digitallibrary/aftmme2011/62.pdfhttp://commons.wikimedia.org/wiki/File:Pelton_wheel_water_turbine,_nozzle_and_bucket_%28Rankin_Kennedy,_Electrical_Installations,_Vol_III,_1903%29.jpghttp://commons.wikimedia.org/wiki/File:Pelton_wheel_water_turbine,_nozzle_and_bucket_%28Rankin_Kennedy,_Electrical_Installations,_Vol_III,_1903%29.jpghttp://hydropower.ornl.gov/HAP/BestPracticeCatComp.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://www.steel.org/~/media/Files/Autosteel/Great%20Designs%20in%20Steel/GDIS%202008/06%20-%2050%20year%20Perspective%20of%20Automotive%20Engineering%20Body%20Materials%20and%20an%20Engineering%20Body%20Materials.pdfhttp://machinedesign.com/article/advanced-high-strength-steels-add-strength-and-ductility-to-vehicle-design-0503http://machinedesign.com/article/advanced-high-strength-steels-add-strength-and-ductility-to-vehicle-design-0503


38/39


31

Shop at India (2012) [online] available from < http://www.shopatindia.com/price/Tata-Nano-LX-

BS-III-Car> [30 November 2012]

Stadolsky, F. Vyas, A. Cuenca, R. Gaines, L. (1995)Life-Cycle Energy Savings Potential fromAluminum-Intensive Vehicles [online] available from

< http://www.transportation.anl.gov/pdfs/TA/106.pdf> [28 November 2012]

Subbarao, R.V.M (n.d.,)Analysis of Intake System for Modern Pelton Wheel [online] Delhi: IIT

Available from [03 December 2012]

Thapa, Bhola. Dahlhaug, G. Ole. Timsina, Madan. Upadhyay, Piyush. Basnet, Ranjil (n.d.,)HVOF

coatings for erosion resistance of hydraulic turbines:Experience of Kaligandaki A

Hydropower Plant[online] available from

[06 December 2012]

Wikipedia (2012a)Lester Allan Pelton [online] availablefrom

[03 December 2012]

Wikipedia (2012b) Pelton wheel [online] availablefrom

< http://en.wikipedia.org/wiki/Pelton_wheel> [03 December 2012]

World auto steel. (n.d.,) ULSAB Programme Report[online] available from

< http://www.worldautosteel.org/projects/ulsab/ultralight-steel-auto-body-ulsab-programme/>

[01 December 2012]
http://www.shopatindia.com/price/Tata-Nano-LX-BS-III-Carhttp://www.shopatindia.com/price/Tata-Nano-LX-BS-III-Carhttp://www.transportation.anl.gov/pdfs/TA/106.pdfhttp://web.iitd.ac.in/~pmvs/mel346/mel346-16.ppthttp://www.drukgreen.bt/library/Documents/CPSU/6.05.%20Thapa%20B.pdfhttp://en.wikipedia.org/wiki/Lester_Allan_Peltonhttp://en.wikipedia.org/wiki/Pelton_wheelhttp://www.worldautosteel.org/projects/ulsab/ultralight-steel-auto-body-ulsab-programme/http://www.worldautosteel.org/projects/ulsab/ultralight-steel-auto-body-ulsab-programme/http://en.wikipedia.org/wiki/Pelton_wheelhttp://en.wikipedia.org/wiki/Lester_Allan_Peltonhttp://www.drukgreen.bt/library/Documents/CPSU/6.05.%20Thapa%20B.pdfhttp://web.iitd.ac.in/~pmvs/mel346/mel346-16.ppthttp://www.transportation.anl.gov/pdfs/TA/106.pdfhttp://www.shopatindia.com/price/Tata-Nano-LX-BS-III-Carhttp://www.shopatindia.com/price/Tata-Nano-LX-BS-III-Car


39/39


Bibliography________________________________________________________________________________

Soboyejo, Wole`. (2002)Mechanical properties of Engineered materials.

New York: Marcel Dekker Inc.

Callister, Jr.D.William. Rethwisch, G. David. (2012) Fundamentals of materials science and

engineering : an integrated approach. 9th

edn. New York: John Wiley & Sons, Inc.,

Kutz, Myer (ed.) (2002)Handbook of Materials Selection. New York: John Wiley & Sons, Inc.,