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Part II, Engineering materials Application of Materials.

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Presentation on theme: "Part II, Engineering materials Application of Materials."— Presentation transcript:

1 Part II, Engineering materials Application of Materials

2 Structural strength Strenth of Materials StiffnessReliabilityLifetime

3 Strength of materials Properties determined at tensile/compression tests Permanent elongation Total elongation

4 Criteria for materials selection plastic materials – yield strength (yield limit) – R e, R p (R e c, R p c) brittle materials – strength limit – R m (R m c ), R m /  Classification of materials (R e, R p0,2 ) low strength< 250 N/mm 2 medium strength N/mm 2 high strength N/mm 2 super high strength> 1500 N/mm 2

5 Stress concentration

6 Stiffness Stiffness D = Ex K(geometric characteristic of cross- section) At tension K = S (cross-section area) At bending K = I (moment of inertia)I = bh 3 /3 Modulus of elasticity NormalShearVolume

7 Modulus of elasticity MaterialE, N/mm 2 x 10 9 Diamond WC SiC Al2O3 TiC Mo & Mo-alloys Co & Co-alloys Ni & Ni-alloys Steels Cast irons Cu & Cu-alloys Ti & Ti-alloys Zn & Zn-alloys Al & Al-alloys Sn & Sn-alloys Graphite Pb & Pb-alloys Plastics Rubbers PVC ,01-0,1 0,003-0,01

8  T   KU, KV – cold brittleness T DBT – ductile-to-brittle transition Reliability (1) Toughness – notch impact energy KU or KV, J – fracture toughness K C, N/mm 2  m 1/2 T DBT T’ DBT T DBT Ductile fracture %

9 Reliability (2) Influence of C, ordinary and alloying elements to KU normal cold worked el steel T DBT T DBT  C T DBT

10 Reliability (3) % of alloying elements Ductile-to-brittle transition T 50,  C

11 Reliability (4) KU, J low strength high strength T KU, KV Grain no. Dependence of KU/KV on temperature Dependence of M toughness of A-grain size

12 Fine and coarse grain steels 1 – killed steel 2 – rimmed steel

13 Influence of microalloying elements Alloying elements, % Grain size of ferrite,  m 2 V Ti Nb

14 Plane strain fracture toughness K 1c At tension K 1c Coefficient of stress intensity [MPa  m 1/2 ]

15 Relationship between K 1c and yield strength Material K 1C, MPa  m 1/2 WC TiC SiC Al 2 O 3 SiO 2 Steels - low carbon - maraging (E) 6 (680) 4 (440) 3 (420) 3 (320) 0,7 (100) Superplastic steels Maraging steels Low- alloyed highly tempered steels Precipitation hardened stainless steels Fracture toughness K 1c, MPa  m 1/2 Yield strength, MPa

16 Life time (1) Fatigue Steels N = 107 Nonferrous alloys N = 108 Impactors: - surface roughness - stress state - stress concentrations  R (R =  min /  max )  -1 – symmetric loading

17 Life time (2) MaterialR p0,2, N/mm 2  -1, N/mm 2 Plain carbon steel - strain hardened - annealed Alloyed steel Al-alloys - wrought alloys - cast alloys Ti-alloys Cu-alloys

18 Life time (3) Creep  = f( , T, t) low temperature T/T m < 0.5 high temperature T/T m > 0.5 Impactors structure alloying (super  creep alloys) – TMT

19 Corrosion Modes of corrosion Chemical Electrochemical Biochemical in dry gases in organic liquids in water containing environments in melt electrolytes

20 Types of corrosion Types of corrosion: a – uniform b – nonuniform c – selective d – spotted e – pitting f – dotted g – under surface h – intercrystal i - stress

21 Chemical corrosion of metals (1) 2 Mg + O 2 = 2 MgO 2 Fe + 3 O 2 = Fe 2 O 3 For protection V oxide > V metal Kui V oxide /V metal > 1 – Cd, Al, Ti, Zr, Zn, Ni, Cr, Fe At high V oks / V met (1,2…2,0)  cracking High temperature corrosion T  1000  C – oxide layer  electroconductive

22 Chemical corrosion of metals (2) Corrosion influencing parameters structure surface treatmentmaterials parameters internal stresses T gas composition velocityenvironmental parameters heating parameters

23 Chemical corrosion of metals (3) Protection alloying ( ) coatings protective atmosphere (at heat treatment) (H 2 + N 2 + H 2 O; CO + CO 2 + N 2 ; etc.)

24 Electrochemical corrosion of metals (1) Moisture + H 2 S, Co 2, So 2, NaCl  electrolyte metals  galvanic pair Normal potential E, V Galvanic series Normal conditionSea water -2,37Mg -1,66AlZn -1,63TiCd -1,18MnAl soft steel -0,76ZnPb -0,74CrSn Ni -0,44Febrass -0,40CdCu -0,25Nimonel (Ni alloy -0,14SnCr-steel (13% Cr) 0,13PbTi +0,34CuCr +0,80Ag +1,20PtAu +1,50AuPt

25 Electrochemical corrosion of metals (2) Microgalvanic pairs at steels Atmosphere Moisture film Metal

26 Electrochemical corrosion of metals (3) Protection (1) Selection of materials Table: Allowed contacts of metals Group IIIIIIIVV MgAlFeNiTi Znplain carbon steel CrCu-Ni alloy CdPbStainless steel Cu-Zn alloy SnCr-steelCu Ag, Au

27 Protection (2) Protective coatings - metallic (less active metals (Cu, Ni, Sn, Ag) – up to coating must be undamage; active (Zn, Co) – protection up to end) - paints, lubricants other - cathodic protection - protector protection - anodic protection - corrosion inhibitors (high molecular matters)

28 Wear Modes of wear MechanicalCorrosive-mechanicalAdhesive -abrasion-oxidizing wear -erosion-fretting corrosive wear -cavitation -fatigue wear

29 Method for wear protection hardening, thermo-chemical treatment overwelding surface alloying coating (chemical, thermo-chemical, thermally sprayed, PVD, CVD, mechanical) selection of pairs (by adhesion)

30 Wear testing methods Description Sliding friction with or without a lubrication Abrasive wear Rolling friction with or without a lubrication

31 Material groups Metals Ceramics Glass Composites Polymers Cermets Glass-ceramics MCM MCMMetal composite materials CCMCeramic composite material PCMPolymeric composite material GCCMGlass-ceramic composite material FRGFiber-reinforced glass CCM PCM GCCM FRG

32 Material group  kg/m 3 R m N/mm 2 R m /  up to Metals and alloys Cast irons Plain carbon steels Alloy steels Al-alloys Cu-alloys Ti-alloys Mg-alloys … … … … … … … Plastics PVC PE PC Fiberglass plastic EP. PC …25 20…40 35…80 30…90 80… Specific strength of materials (1)

33 Specific strength of materials (2) Material group  kg/m 3 R m N/mm 2 R m /  up to Cera- mics Al 2 O 3 TiO 2 3Al 2 O 3 2SiO 2 SiC (  -modif.) Si 3 N …400 70… … … … Compo -sites Al-B (30%) Al-B (50%) Fiberglass plastic EP EC Carbon-Carbon composite 3-directions …90 80… (2000  C) 5 (3000  C) WoodPine Oak 550 II 690 II

34 Basic physical and mechanical properties of construction materials (1) PropertyMetalsCeramicsPolymers Density,  kg/m 3 x (average. 8) 2-17 (average. 5) 1-2 T S,  C Low.  High. Sn232, W3400 High  4000 Low HardnessAverageHighLow WorkabilityGoodPoorGood Tensile strength R m, MPa  2500  400  120 Compressive strength R m c, MPa  2500  5000  350

35 Basic physical and mechanical properties of construction materials (2) PropertyMetalsCeramicsPolymers Modulus of elasticity, E GPa 40   4500,001  3,5 Creep resistance at high temperatures PoorOutstanding- Thermal expansion Average  High Low  Average Very high Thermal conductivity Average Average (mostly lowers then t   ) Very high Electrical properties ConductorsIsolators Chemical inertness Low  average Outstanding Good in general

36 Thank you for attention


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