TAFE NSW -Technical and Further Education Commission ENMAT101A Engineering Materials and Processes Associate Degree of Applied Engineering (Renewable Energy Technologies) Lecture 26 – Causes of failure

TAFE NSW -Technical and Further Education Commission Causes of failure EMMAT101A Engineering Materials and Processes Reference TextSection Higgins RA & Bolton, Materials for Engineers and Technicians, 5th ed, Butterworth Heinemann Ch 26 Reference TextSection

TAFE NSW -Technical and Further Education Commission 26.2 Causes of failure (Higgins 26.2) EMMAT101A Engineering Materials and Processes Overstressing (abuse) Fatigue (Alternating loads) Creep (High temp) Sudden loads (earthquake, storm, accident) Expansion (or contraction) Thermal cycling (hot/cold stresses) Degradation (Environmental)

TAFE NSW -Technical and Further Education Commission 26.2 Causes of failure (Higgins 26.2) EMMAT101A Engineering Materials and Processes 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

TAFE NSW -Technical and Further Education Commission 26.3 Non-destructive testing (Higgins 26.3) EMMAT101A Engineering Materials and Processes The detection of surface cracks and flaws Penetrant methods

TAFE NSW -Technical and Further Education Commission 26.3 Non-destructive testing (Higgins 26.3) EMMAT101A Engineering Materials and Processes Magnetic particle methods

TAFE NSW -Technical and Further Education Commission 26.3 Non-destructive testing (Higgins 26.3) EMMAT101A Engineering Materials and Processes Acid pickling methods

TAFE NSW -Technical and Further Education Commission 26.3 Non-destructive testing (Higgins 26.3) EMMAT101A Engineering Materials and Processes The detection of internal defects X-ray methods Gamma-ray methods

TAFE NSW -Technical and Further Education Commission 26.3 Non-destructive testing (Higgins 26.3) EMMAT101A Engineering Materials and Processes 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/E p

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by oxidation (Higgins 26.4) EMMAT101A Engineering Materials and Processes Oxidation Attack by sulphur

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) EMMAT101A Engineering Materials and Processes Electrolytic corrosion is like a Battery.

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) EMMAT101A Engineering Materials and Processes The Electrochemical (or Galvanic) Series

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) EMMAT101A Engineering Materials and Processes Cladding of metal sheets

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) EMMAT101A Engineering Materials and Processes Cladding of metal sheets

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) EMMAT101A Engineering Materials and Processes Rusting of iron and steel

TAFE NSW -Technical and Further Education Commission 26.6 The protection of metal surfaces (Higgins 26.6) EMMAT101A Engineering Materials and Processes Painting Stove-enamelling Coating the surface with another metal Hot dipping Spraying Sherardising Electroplating Cladding Protection by oxide coatings

TAFE NSW -Technical and Further Education Commission 26.6 The protection of metal surfaces (Higgins 26.6) EMMAT101A Engineering Materials and Processes Metals and alloys which are inherently corrosion-resistant Galvanic protection

TAFE NSW -Technical and Further Education Commission 26.4 Degradation of metals by electrolytic corrosion (Higgins 26.4) EMMAT101A Engineering Materials and Processes Stress corrosion

TAFE NSW -Technical and Further Education Commission 26.7 Stability of plastics (Higgins 26.7) EMMAT101A Engineering Materials and Processes Weathering of plastics materials Perishing of rubbers Stress cracking and crazing of polymers Stability to solvents

TAFE NSW -Technical and Further Education Commission 26.8 Preservation of timber (Higgins 26.8) EMMAT101A Engineering Materials and Processes Insect pests Fungus attack

TAFE NSW -Technical and Further Education Commission 26.9 Service life (Higgins 26.9) EMMAT101A Engineering Materials and Processes 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.

TAFE NSW -Technical and Further Education Commission EMMAT101A 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 LibraryMt Druitt College Library: DVD 671.5/JOIN Joining Metals NotesJoining Metals Notes (pdf) Recommended Viewing: All sections.

TAFE NSW -Technical and Further Education Commission EMMAT101A Engineering Materials and Processes Wikipedia: Welding Resources. Ashby diagrams

TAFE NSW -Technical and Further Education Commission Glossary EMMAT101A Engineering Materials and Processes Sacrificial anode Galvanising Electro-negativity Stress corrosion Electrolysis Oxidation Ductile/brittle failure Fatigue failure

TAFE NSW -Technical and Further Education Commission QUESTIONS: Joining of Materials Higgins Ch26, Newell, Timmings, Sheedy, Callister, Ashby 1.Define all glossary terms 2.(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. 3.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 4.Briefly outline the processes by which plastics suffer degradation 5.Explain the differences between corrosion resistance of platinium and titanium. What other metals would fall into each of these two groups? 6.Describe ways to counter galvanic corrosion in PhotoVoltaic systems. EMMAT101A Engineering Materials and Processes