BK50A2700 Selection Criteria of Structural Materials

1. BK50A2700 Selection Criteria of Structural Materials Lesson 2 2014

2. REPETITION 2:Material selection based on wear resistanceMaterial selection based on corrosion resistance Lesson 2 2014

3. The goal of this lesson

4. Our goal is, that after this lesson, students are able to recognize the importance of affecting wear and corrosion phenomena for material selection.

5. Material selection based on wear resistance

6. Note! • To ensure proper material selection it is important to recognize the affecting wear phenomenon/ phenomena!

7. JOINT EFFECTS OF WEAR PHENOMENA JOINT EFFECTS OF WEAR PHENOMENA ADHESIVE WEAR WEAR PHENOMENA FATIGUE WEAR TRIBOCHEMICAL WEAR JOINT EFFECTS OF WEAR PHENOMENA JOINT EFFECTS OF WEAR PHENOMENA ABRASIVE WEAR

8. Note! • Different wear phenomena can affect simultaneously • Different wear phenomena can affect consecutively (they can form “chains” of wear phenomena) • Numerical values of wear resistance are required to compare the wear resistance of optional materials objectively!

9. MATERIAL PAIR - Lubricated - Non-lubricated - Self lubricated - Oil - Crease SURFACE ROUGHNESS MEDIA WEAR Main aspects in material selection - HD - EHD - Border - Mixed - Adhesive - Abrasive - Fatigue wear - Tribochemical wear WEAR PHENOMENA LUBRICATION CONDITIONS ENVIRON-MENTAL CONDI-TIONS - Slow speed - High speed - Continuous - Cyclic TYPE OF MOTION

10. ADHESIVE WEAR Surface 1 MOTION A surface peak cold welds with the surface peak on the opposite surface. Surface 2

11. ABRASIVE WEAR Surface 1 Harder MOTION A harder abrasive particle wears the softer surface. Surface 2 Sowter

12. TRIBOCHEMICAL WEAR

13. FATIGUE WEAR

14. Carburized steel 20NiCrMo 5 Polymer PA6.6

15. FRICTION COEFFICIENT µ FRICTION COEFFICIENT µ PA 6.6 PA 6.6 + 15% PTFE 1 0.8 0.6 0.4 0.2 0 1 0.8 0.6 0.4 0.2 0 50 150 250 50 150 250 T [ºC] TEMPERATURE T [ºC] TEMPERATURE

16. Centrifugal cast bronze GZ-CuZn12 Carburized steel 16MnCr5

17. Heavy loads Wear resistance increases Thermal coatings Tungsten carbides, cobolt WC/Co Chromium carbides and nitrides CrC, CrN Ceramic coatings Nitridized steels Carburized steels Small loads

18. Heavy loads Thermal coatings WC/Co Thick ceramic coatings CrC CrN Borium steels Nitritized steels Carburized steels Wear restistance increases Thermal coatings WC/Co Plasma coating Oxidation:Cr, Al CrC, CrN Thin ceramic coatings Nitridized steels Carburized steels Austenic stainless steels Small loads

19. Wear resistance steels are utilized e. g. in crane rails.

20. Bearing steel 100Cr6

21. STRENGTH OF ADHESIVE REACTION Cr Ni Fe Ti Cu Al Zn Sn Pb In Mg In Pb Sn Mg Zn Al Cu Ti Highly intensive adhesive reaction Fairly intensive adhesive reaction No adhesive reaction Fe Ni Cr

22. Archard’s equation : V =ki×F× s • V = material loss due to wear • ki = material pair coefficient • F = affecting perpendicular force against the surface • s = motion distance • The criterion for wear resistance comparison is the material pair coefficient ki

23. Advanced equations: V =Ki×SC2× RC3 • V = material loss due to wear • S = contact stress of the components • R = number of loading cycles • Ki ,C2,C3 = coefficient describing the material pair, surface roughness and loading case • Advanced equation takes care of the effect of surface profile s and cyclic loading on wear • Remember that sometimes the friction coefficient between the materials gives a measureable value for possible wear rate!

24. Material selection based on corrosion resistance

25. Note! • To ensure proper material selection it is important to recognize the affecting corrosion phenomenon! • It is also necessary to take care of other simultaneous loading conditions with corrosion, such as tensile stress, temperature or wear! • Numerical values are needed to evaluate and compare objectively the corrosion resistance of each optional material. See e.g. standards ISO 9223 and ISO 9224 for the corrosion speed of steels.

26. Surface corrosion Uniform corrosion CORROSION PHENOMENA Pitting corrosion Localized corrosion Crevice corrosion High-temperature corrosion Galvanic corrosion Contact corrosion Erosion Mechanical surface loading Cavitation Fretting Corrosion under stress loading Stress corrosion Corrosion fatigue Selective corrosion Intergranular corrosion Bronzes Selective leaching Cast irons

27. UNDER THE GASKET THERE IS THE RISK BOTH OF WEAR AND CORROSION

28. EXAMPLE OF CRACK AND GALVANIC CORROSION ALUMINIUM BODY FITTING BASED ON CLEARANCE GOLD COATED CENTRE PIN SMA-CONNECTOR MW-FILTER RESONATOR PINS

29. FRETTING CORROSION Clearance in fitting H6/m6 H6 m6 Bearing assembly

30. STRESS σ FATIGUE WITHOUT CORROSION ENDURANCE LIMIT FATIGUE IN CORROSIVE ENVIRONMENT N NUMBER OF LOAD CYCLES

31. - Uniform corrosion - Localized corrosion - Galvanic corrosion - Erosion and cavitation - Fretting - Intergranular corrosion - Selective leaching - Stress corrosion - Corrosion fatigue MATERIAL PAIR CORROSION PHENOMENON TEMPERATURE CORROSION Aspects to affect material selection STRESS CONDITIONS - Coating - Casting - Painting MANUFACTURING TECHNOLOGY CHEMICAL ENVIRONMENTAL

32. Steel pipes in energy transportation

33. STEEL/STAINLESS STEEL COATED POLYMERS ALUMINIUM ALLOYS COPPER ALLOYS CABLE JOINT

34. SURFACE CORROSION OF THE HUB IN A CABLE JOINT

37. Note! • It is not enough to ”select” stainless steel to avoid corrosive damages! There are four different types of stainless steels and they have totally different application areas: • Austenitic stainless steels • Martensitic stainless steels • Ferritic stainless steels • Duplex steels

38. CONDITIONS x COUNTRY SIDE SEASIDE CORROSION VELOCITY 10x µm/YEAR A = AUSTENITIC STAINLESS STEEL B = FERRITIC STAINLESS STEEL C = ZINC COATED STEEL D = CARBON STEEL