dissertation global and local fracture properties of metal matrix ...

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4.1.2.3. Fracture mechanics tests Section 4 Disk-shaped compact (DCT) specimens with a thickness B = 10 mm, a width of W = 17 mm, and an initial crack length of ao ≈ 8 mm were machined for the fracture mechanics tests (Fig. 4.8). To insert the pre-crack in specimens, they are subjected to cyclic compression loading with ∆K = 10 MPa m and further to cyclic tensile loading with ∆K = 5 MPa m . Fracture mechanics tests are conducted as for the cast MMCs. Due to the small size of the disk-shaped compact specimens, a video-extensometer is employed to measure the load line displacement. The J-integral resistance curves are evaluated according to ASTM standards E1320-1 [70]. It should be noted that due to the low ductility of the PM MMCs, the J0.2/Bl -values cannot be determined. Therefore, only the values of the fracture toughness, Ji, are given in Table 4.3. Fig. 4.8. A disk-shaped compact specimen made of the Al6061-10%SiC PM-MMC. 4.1.3. The relations between the global mechanical properties It is seen from Table 4.2 that for the cast MMCs, the yield strength, σy, and the ultimate tensile strength, σUTS, increase with increasing aging conditions and particle volume fraction, whereas the values of the fracture initiation toughness, the strain hardening coefficient, and the fracture strain show an opposite behavior. A dependency between the mechanical properties similar to that observed in [16, 21] are found for investigated cast MMCs: εfr and N linearly decrease with increasing yield strength, 37
εfr [%] εfr [%] N 16 12 8 4 0 150 250 350 450 16 12 8 4 0 0,25 0,2 0,15 0,1 0,05 0 σ y [MPa] Section 4 10% 15% 20% a) b) 0 0,1 0,2 0,3 Ν c) d) 150 250 350 450 σy [MPa] 10% 15% 20% 10% e) f) Fig. 4.9. The relation between the mechanical properties of: a-b) the cast MMCs, c-d) the cast MMCs, e-f) the PM-MMC (to be continued). 38 N J 0.2 [kN/m] J i [kN/m] 0,25 0,2 0,15 0,1 0,05 0 12 8 4 150 250 350 450 σy [MPa] 0 150 250 350 450 6 5 4 3 2 1 σ y [MPa] 0 150 200 250 300 350 400 σ y [MPa] 10% 15% 20% 10% 15% 20% 10%
Page 1 and 2: MONTANUNIVERSITÄT MONTANUNIVERSIT
Page 3 and 4: TABLE OF CONTENTS 1. Introduction 5
Page 5 and 6: 7.4.4. The effect of ECAP on the lo
Page 7 and 8: Section 1 The main results of this
Page 9 and 10: Section 2 2.2. The influence of the
Page 11 and 12: Section 2 high strength, fine reinf
Page 13 and 14: Section 2 etched to mark the inclus
Page 15 and 16: Section 2 (4.) The specimen prepara
Page 17 and 18: Section 3 Fig. 3.1. The digital ele
Page 19 and 20: height [µm] height [µm] 10 0 -10
Page 21 and 22: Section 3 Fig. 3.5. The observation
Page 23 and 24: Section 3 3.3.2. The determination
Page 25 and 26: Section 3 The Eshelby tensor does n
Page 27 and 28: equivalent stress Section 3 Fig. 3.
Page 29 and 30: Assume σ m eq Calculate matrix sec
Page 31 and 32: Section 4 Table 4.1. Chemical compo
Page 33 and 34: 4.1.1.3. Fracture mechanics tests S
Page 35 and 36: Section 4 Fig. 4.4. A view of a com
Page 37: Section 4 Table 4.3. Mechanical pro
Page 41 and 42: Section 4 4.2. The effect of the he
Page 43 and 44: Section 4 It should be noted that n
Page 45 and 46: CODi [µm] 40 30 20 10 0 Section 4
Page 47 and 48: Section 4 Table 4.4. Results of the
Page 49 and 50: CODi [µm] COD i [µm] CODi [µm] 2
Page 51 and 52: Cast MMCs 10%-RT 10%-8h 10%-24h 10%
Page 53 and 54: COD vi [µm] COD vi [µm] CODvi [µ
Page 55 and 56: CODvi [µm] CODvi [µm] 80 60 40 20
Page 57 and 58: Section 4 Table 4.6. The values of
Page 59 and 60: σ p max [MPa] σ p max [MPa] σ p
Page 61 and 62: σ p max [MPa] σ p max [MPa] 1200
Page 63 and 64: σ interf max [MPa] σ interf max [
Page 65 and 66: Section 4 4.5. The relation between
Page 67 and 68: Section 4 Table 4.9. Conditions for
Page 69 and 70: Ln(Ln(1/(1-F σ))) Ln(Ln(1/(1-F σ)
Page 71 and 72: Section 5 diameter of 2…8 µm and
Page 73 and 74: MnS-inclusion r θ MnS-inclusion Se
Page 75 and 76: σ interf [MPa] σ interf [MPa] σ
Page 77 and 78: Section 6 where n is the number of
Page 79 and 80: Ji [kN/m] J i [kN/m] 25 20 15 10 5
Page 81 and 82: Section 7 7.2. A model by Tan and Z
Page 83 and 84: Section 7 its initial length, li. O
Page 85 and 86: 1 µm Section 7 5 µm Fig. 7.3. A s
Page 87 and 88: Section 7 a) b) c) Fig. 7.4. Micros
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Section 7 It is important that no p
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Section 7 between the Rtot and the
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Section 7 Fig. 7.8. The fracture su
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10 z [mm] 5 -10 -15 Section 7 0 -20
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Section 7 Table 7.3. Data on measur
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8. Summary Section 8 This work deal
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Section 8 The effect of the homogen
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Table 9.1. Data on stress for Speci
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Table 9.11. Data on stress for Spec
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Table 9.17. Results of the stereoph
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1 2 1 2 3 3 4 5 6 5 9 119 7 7 8 9 6
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8 9 10 6 10 122 11 12 13 14 11 12 1
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9 10 11 12 13 124 50 µm Fig. 9.6.
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1 2 1 2 3 3 4 4 126 5 5 6 9 7 50 µ
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1 1 2 2 3 4 3 4 5 5 128 6 7 6 7 50
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Fig. 9.12. Fracture surface with ma
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1 2 3 1 2 3 4 5 6 7 8 9 10 4 5 132
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Fig. 12.36. Fracture surface of the
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[14] Lewandowski JJ, Liu C, Hunt WH
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[42] Rice JR, Rosengren GF. Plane s
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[70] ASTM E1820-01, “Standard Tes
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