METALLURGICAL REPORT NUMBER: MF781P-10 Request for...Portable Hardness Testing: It was conducted by means of the IMPACT (Time) TH 130 Integrated Portable Hardness Tester. Procedure

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METFOCUS METALLURGICAL SERVICESFOR METALLURGICAL SERVICES AND SOLUTIONS

Reg No: 2002/038112/23. Vat No: 4940203377

Tel No: (017) 843 1651Fax No: (017) 843 1457Cell No: 0829044624E-Mail Address: [email protected]: www.metfocus.co.za

METALLURGICAL REPORT NUMBER: MF781P-10

THE METALLURGICAL INVESTIGATION INTOTHE CAUSE OF FAILURE OF THE NUMBER: 3 OIL PUMP SHAFT

PRETORIA WEST POWER STATION

CONFIDENTIAL

Managing Member: Loucas Kometas

63 Lange StreetCarolina 1185MpumalangaPo Box 1853Carolina1185 MpumalangaSouth Africa

mailto:[email protected]

http://www.metfocus.co.za/

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MF781P-10

METALLURGICAL REPORTCONFIDENTIAL

CONTENTS Page/Section Number

(1) Subject 3

(2) Details 3

(3) Visual Examination 4

(4) Non-Destructive Examination 4

(5) In – Situ Metallographic Replication 5

(6) Chemical & Portable Spectroscopic Analysis 5

(7) Hardness Testing 6

(8) Microscopic Examination 6

(9) Observations and Recommendations 6

(10) Test Methods & Techniques 6

(11) References 7

(12) Photographs Section Number: 12

(13) Microphotographs Section Number: 13

(14) General Conditions Section Number: 14

Compiled By: Loucas KometasChief Metallurgist5 March 2010

CONFIDENTIAL

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Reg No: 2002/038112/23. Vat No: 4940203377


Metallurgical Report Number MF781P-10CONFIDENTIAL

Metfocus Metallurgical Services was requested by Mr Jan Kuik of Pretoria West Power Station, toconduct a Metallurgical Investigation as to the likely cause of the Failure of the Number: 3 Mail OilPump Shaft.

The following details were made available:

Power Station: Pretoria West

Unit Number: 3

Failed Component: Main Oil Pump

Year of Manufacture: 1952

Year of Replacement: 2005

Running Hours: +/- 10370 Hours

Date of Failure: TBA

Drawing Number: No Drawing is Available

Material Type: EN 9, i.e 070M55

(1) SUBJECT:

(2) DETAILS:

63 Lange StreetCarolina 1185MpumalangaPo Box 1853Carolina1185 MpumalangaSouth Africa



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The visual examination of the failed shaft revealed the following:

Failure occurred at the stepped area on the drive side of the shaft, i.e where the journal meets themain shaft. See photograph number: 1. It was also observed that the radius in this area wasvirtually nonexistent, i.e it appears as if it is a sharp edge, with no generous radius.

The fracture face displayed numerous fatigue initiation sites, initiating predominantly from thenon-radius sharp corner and also from other areas or sites on the shaft outer circumference – weldoverlay. In general the fracture face was not entirely flat, as is normally observed on classicalfatigue fracture faces. Instead, longitudinal faceted fractured areas were observed to be present.See photograph number: 2. Fatigue striation marks were also found to be present across the entirefractured face/s, as mentioned above.

No signs of any abnormal or excessive gear teeth wear or damage was observed.

The examination of the key and the keyway did not reveal any un-acceptable design, fit oroperational artefacts. See photograph number: 3.

Random, small crack-like indications / marks were found to be present on the occasional geartooth running faces.

The non-destructive examination of the failed area and the gear teeth, revealed the following:

No signs of any un-acceptable or deleterious defects or cracks were found to be present on theshaft, other than the occasional small circumferential weld indication found in the recessedshoulder area, i.e associated with the fracture face / area. See photograph number: 4 & 5.

The random, small crack-like indications that were found to be present on the occasional geartooth running face were lightly ground and re-tested. It thus appears that they are or were deeperthan normal plastically deformed surface scratch marks.

Table Number: 1,indicates the location of the replicated areas:

Table Number: 1

ReplicatedArea:

Description:Photograph

Number:

R1AReplica taken on the Outside

Diameter / Surface of the FailedDrive Section / Journal

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R2BReplica taken on the Shaft

Cross Section - Core7

(5) IN-SITU METALLOGRAPHIC REPLICATION:

(3) VISUAL EXAMINATION:

(4) NON-DESTRUCTIVE EXAMINATION:

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R3CReplica taken on the

Longitudinally Sectioned FailedJournal

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The chemical analysis of a sample taken of the shaft core area, revealed the results & the composition,as is reflected in Table Number: 2.

Table Number: 2

The Portable Spectroscopic Material Analysis of the journal weld overlay (build-up) layer revealed that itwas of a compatible material to that of the shaft core material.

The hardness testing of the selected cut out sections / samples and the replicas, are reflected in TableNumber: 3

Table Number: 3

Area Tested: Hardness HV:

Core - Impression No: 1 191




Element: Shaft / Core:

Carbon 0,55

Manganese 0,75

Sulphur 0,053

Phosphorus 0,024

Silicon 0,26

Chromium 0,08

Molybdenum 0,03

Nickel 0,25

Copper 0,57

Aluminium ≤ 0,005

Vanadium ≤ 0,005

Niobium ≤ 0,005

Boron ≤ 0,005

Iron Matrix

MaterialEquivalent

EN 9 – 070M55

(7) HARDNESS TESTING:

(6) CHEMICAL & PORTABLE SPECTROSCOPIC ANALYSIS:

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Weld Overlay – Impression No: 1 195



HAZ – Impression No: 1 240



The microscopic examination of the replicas and the cut out samples, revealed the following:

The general core microstructure of the replicated areas A & B, was found to be composed of apearltic / bainitic phase, with the grain boundaries comprising of cementite. See microphotographnumber: 1 & 2.

The microphotographs number: 3, 4, 5, 6, 7 & 8, display the microstructural observations andfindings that were made relating to the weld overlay of the failed shaft journal, etc.

The following observations, conclusion and recommendations are made:

The main oil pump failed due to the mechanism of fatigue. The initiation sites for the fatiguemechanism / cracking was introduced by the sub-standard weld overlay (build –up) that wasconducted on the journal area. An abundance of “build in” weld defects, particularly in thestepped shoulder area is postulated to have been the initial driving mechanism for this failure tohave occurred. In addition to this the absence of a generous radius at the above-mentioned area,further assisted with the crack initiation phase of the failure.

It was also established that all four journal areas of the two shafts were subjected to this type ofweld overlay process.

The hardness readings were found to be acceptable and in line with this type of base material.

RECOMMENDATIONS:

It is recommended that the other units pump / shafts are inspected for the presence of the similarsymptoms, i.e that were observed in this case.

The following test methods and techniques were utilised during this Metallurgical FailureInvestigation:

Microscopic Examination: This was performed by utilising the Zeiss Axioskop MetallurgicalOptical Microscope, fitted with a Panasonic Monitor and a Sony Video Graphic MicrophotographPrinter – UP 860 CE.

(9) OBSERVATIONS AND RECOMMENDATIONS:

(8) MICROSCOPIC EXAMINATION:

(10) TEST METHODS AND TECHNIQUES:

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Replication: This was conducted by means of the In-Situ Metallographic Technique, usingCellular Acetate Foil. Procedure Number, MTS C – 002.

Microphotographs: They were taken by the Leadtek TV 2000 XP soft wear and technique.

Photography: All the photographs for this metallurgical assignment were taken by means ofthe Canon PowerShot A40 Digital Camera.

Etching: The micro samples and the replicas were etched by means of a 3% Nital Solution.

Chemical Analysis: This is conducted by means of the Spectrometric method and is traceableback to report number 5597. Scrooby’s Laboratory Service cc.

Portable Spectroscopic Material Analysis: The Clandon Metascope Instrument was used forthis Analysis. Procedure No: MTS C - 004.

Magnetic Particle Inspection: This testing was conducted by means of the Gammatec Yoke,using the traditional white back ground and then applying the black ink. Procedure Number MTS0 – 0006.

Non-Destructive Examination: This examination was conducted by means of the Dye PenetrantMethod, using the normal red penetrant and the white developer technique. Procedure NumberMTS 0 – 0006.

Laboratory Hardness Testing: This was conducted by means of the Leco V 100, benchhardness tester. Procedure No: C Met Lab 016. Calibration Certificate No: MTS 15318.

Portable Hardness Testing: It was conducted by means of the IMPACT (Time) TH 130Integrated Portable Hardness Tester. Procedure No: MTS C 0011.

Metals Handbook. Ninth Edition Volume 11. Failure Analysis and Prevention.

R.D. Barer and B.F. Peters. Why Metals Fail. Sixth printing 1991.

D.S. Clark and W.R. Varney. Physical Metallurgy for Engineers. Second Edition.

Lester E. Alban. Systematic Analysis of Gear Failures. American Society for Metals. Metals Park.Ohio 44073.

Loucas KometasCHIEF METALLURGIST5 March 2010METFOCUS METALLURGICAL SERVICES

(11) REFERENCES:

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(12) PHOTOGRAPHS

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PHOTOGRAPH NUMBER: 1

Photograph showing the Failure Fracture Face



Photograph showing the Longitudinal Surface Cracking, which isassociated with the Weld Overlay

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Photograph showing the Key and the Keyway

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Photograph showing the Indications that were observed by the NDT method

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Photograph showing the Indications that were observed by the NDT method

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Photograph showing the Replicated Area Number: R1A

R1A

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Photograph showing the Replicated Area Number: R2B

R2B

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Photograph showing the Replicated Area Number: R3C.The Arrows indicate some of the Locations of Weld Defects

R3C

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(13) MICROPHOTOGRAPHS

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MICROPHOTOGRAPHS

Microphotograph No: 1The General Microstructure of the Shaft Core Parent Material

Magnification: +/- 400X

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MICROPHOTOGRAPHS

Microphotograph No: 2The General Microstructure of the Shaft Core Parent Material, as

was taken at the Replicated Area Number: R2BMagnification: +/- 400X

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MICROPHOTOGRAPHS

Microphotograph No: 3The General Microstructure of the Weld Deposit Overlay, i.e Weld Build-Up


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MICROPHOTOGRAPH

Microphotograph No: 4The General Microstructure of the Weld Overlay Fusion Line at the Shaft Transition Area


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MICROPHOTOGRAPHS

Microphotograph No: 5One Weld Micro Crack that was observed on the Replicated Area Number: R3C


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MICROPHOTOGRAPHS

Microphotograph No: 6One Weld Micro Crack that was observed to be propagating into the

Shaft Parent Material at the Failed Transition Shoulder AreaMagnification: +/- 200X

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MICROPHOTOGRAPHS

Microphotograph No: 7Weld Defects & Porosity found at the Replicated Area Number: R3C


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MICROPHOTOGRAPHS

Microphotograph No: 8Weld Defects, Lack of Fusion, Slag & Porosity found at the Replicated Area Number: R3C


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(14) GENERAL CONDITIONS

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Reg No: 2002/038112/23. Vat No: 4940203377


GENERAL CONDITIONS

(1) While every care has been taken in obtaining the results recorded andexpressing any opinion. No warranties are given in regard to this repand we shall under no circumstances be liable for any consequentialdamage.

(2) No verbal warranties or representation made by our employees, shalbinding on us.

(3) We shall not be responsible for any consequential loss or damage oinjury of whatever nature and howsoever arising, which may be incor suffered by you or any other person from any cause whatsoeverwhether occasioned by our neglect or default or otherwise.

(4) Failing receipt of written notice from you within seven (7) days aftecompletion and delivery of work, that it is not satisfactory. It shall bdeemed that the work has been duly completed to your satisfaction aour obligation to you shall cease.

(5) Investigational and examination work is undertaken, on the clearunderstanding that liability for fees quoted, is not dependent upon asuccessful outcome to the project.In these instances, fees are charged according to the amount of workperformed and not necessarily to the results obtained.

(6) Samples and replicas will be retained for 7 days.

63 Lange StreetCarolina 1185MpumalangaPo Box 1853Carolina

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METALLURGICAL REPORT NUMBER: MF781P-10 Request for...Portable Hardness Testing: It was conducted by means of the IMPACT (Time) TH 130 Integrated Portable Hardness Tester. Procedure