Lecture 26 – Causes of failure Prescribed Text: Ref 1: Higgins RA & Bolton, 2610. Materials for Engineers and Technicians, 5th edition, Butterworth Heinemann. ISBN: 9782656267696 Readings: Callister: Callister, W. Jr. and Rethwisch, D., 2610, Materials Science and Engineering: An Introduction, 8th Edition, Wiley, New York. ISBN 9780470426977 Ashby 1: Ashby, M. & Jones, D., 2611, Engineering Materials 1: An Introduction to Properties, Applications and Design, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN: 9780080966656 Ashby 2: Ashby, M. & Jones, D., 2611, Engineering Materials 2: An Introduction to Microstructures and Processing, 4th edition, Butterworth-Heinemann, Oxford UK. IBSN: 9780080966687   Lecture (2 hrs): Ref 1, Ch 1: Engineering materials; Ref 1 Ch 2: Properties of materials. Laboratory 1 (2 hrs): Hardness test Callister: Ch 1, 2, 26-26 Ashby 1: Ch 1, 2 Ashby 2: Ch 1 1

Causes of failure Reference Text Section Higgins RA & Bolton, 2610. Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann Ch 26 Reference Text Section Engineering Materials and Processes

26.2 Causes of failure (Higgins 26.2) Overstressing (abuse) Fatigue (Alternating loads) Creep (High temp) Sudden loads (earthquake, storm, accident) Expansion (or contraction) Thermal cycling (hot/cold stresses) Degradation (Environmental) Engineering Materials and Processes

26.2 Causes of failure (Higgins 26.2) 26.2.1 Types of fracture surfaces Ductile failure with metals Brittle failure with metals Fatigue failure with metals Failure with polymers Failure with ceramics Failure with composites Engineering Materials and Processes

26.3 Non-destructive testing (Higgins 26.3) 26.3.1 The detection of surface cracks and flaws Penetrant methods Engineering Materials and Processes

26.3 Non-destructive testing (Higgins 26.3) Magnetic particle methods Engineering Materials and Processes

26.3 Non-destructive testing (Higgins 26.3) Acid pickling methods Engineering Materials and Processes

26.3 Non-destructive testing (Higgins 26.3) 26.3.2 The detection of internal defects X-ray methods Gamma-ray methods Engineering Materials and Processes

26.3 Non-destructive testing (Higgins 26.3) Ultrasonic testing: Principle of ultrasonic testing. LEFT: A probe sends a sound wave into a test material. There are two indications, one from the initial pulse of the probe, and the second due to the back wall echo. RIGHT: A defect creates a third indication and simultaneously reduces the amplitude of the back wall indication. The depth of the defect is determined by the ratio D/Ep Engineering Materials and Processes

26.4 Degradation of metals by oxidation (Higgins 26.4) 26.4.1 Attack by sulphur Engineering Materials and Processes

26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) Electrolytic corrosion is like a Battery. Engineering Materials and Processes

26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) 26.5.1 The Electrochemical (or Galvanic) Series Engineering Materials and Processes

26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) 26.5.2 Cladding of metal sheets Engineering Materials and Processes

26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) 26.5.2 Cladding of metal sheets Engineering Materials and Processes

26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) 26.5.3 Rusting of iron and steel Engineering Materials and Processes

26.6 The protection of metal surfaces (Higgins 26.6) 26.6.1 Painting 26.6.2 Stove-enamelling 26.6.3 Coating the surface with another metal Hot dipping Spraying Sherardising Electroplating Cladding 26.6.4 Protection by oxide coatings Engineering Materials and Processes

26.6 The protection of metal surfaces (Higgins 26.6) 26.6.5 Metals and alloys which are inherently corrosion-resistant 26.6.6 Galvanic protection Engineering Materials and Processes

26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) 26.5.4 Stress corrosion Engineering Materials and Processes

26.7 Stability of plastics (Higgins 26.7) 26.7.1 Weathering of plastics materials 26.7.2 Perishing of rubbers 26.7.3 Stress cracking and crazing of polymers 26.7.4 Stability to solvents Engineering Materials and Processes

26.8 Preservation of timber (Higgins 26.8) 26.8.1 Insect pests 26.8.2 Fungus attack Engineering Materials and Processes

26.9 Service life (Higgins 26.9) • External loading levels, rate of loading (impact loading), frequency of loading (fatigue), duration of loading (creep). • Material property degradation (corrosion). • Defects in the form of cracks, porosity (in castings), cavities (in welds) introduced during manufacturing. • Conditions under which used, e.g. temperature, temperature cycling, humidity, chemicals, contact with other materials. • Bad design features such as the presence of notches, sharp corners, small holes, surface roughness. • Lack of, or inappropriate, maintenance. Engineering Materials and Processes

Videos Joining Metals Sheppard, Phil. Bendigo, Vic. : Classroom Video, c2006. DVD (29 min.). An introduction to the methods of joining metals, including riveting and fusion and non-fusion methods of welding. Mt Druitt College Library: DVD 671.5/JOIN Joining Metals Notes (pdf) Recommended Viewing: All sections. h ttp://www.matweb.com S how this website on screen. Will be using this later. Engineering Materials and Processes 22

Resources. Wikipedia: Welding Ashby diagrams h ttp://www.matweb.com S how this website on screen. Will be using this later. Engineering Materials and Processes 23

Glossary Sacrificial anode Galvanising Electro-negativity Stress corrosion Electrolysis Oxidation Ductile/brittle failure Fatigue failure Engineering Materials and Processes

QUESTIONS: Joining of Materials Higgins Ch26, Newell, Timmings, Sheedy, Callister, Ashby Define all glossary terms (a) Explain what is meant by the term corrosion. (b) List three essential conditions for corrosion to occur. (c) Describe how an anode and cathode can be formed. (d) Describe how corrosion can be controlled or prevented. Briefly describe the different types of corrosion listed below: (a) uniform (general) corrosion (b) galvanic corrosion (c) crevice corrosion (d) stress corrosion (e) corrosion fatigue (f) de-alloying (selective leaching), for example de-zincification (g) high temperature (dry) oxidation corrosion Briefly outline the processes by which plastics suffer degradation Explain the differences between corrosion resistance of platinium and titanium. What other metals would fall into each of these two groups? Describe ways to counter galvanic corrosion in PhotoVoltaic systems. http://www.civicsolar.com/node/10621 http://www.youtube.com/watch?v=1GFst2IQBEM Engineering Materials and Processes 25