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

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Section 5 Table 5.2. The mechanical properties of the mild steel St37. the MnS-inclusions, on average, by about a factor of (5÷7). The dimple length is comparable to the length of the MnS inclusions. It should be noted that we consider in our analysis only particles forming primary voids near the crack tip, therefore, Fe3C particles, forming very small equiaxed cavities during the void coalescence will not be taken into account. 5.2. The effects of the particle location and the inclusion size on the CODi- and CODvi- values Material E [GPa] σy [MPa] Nine MnS-inclusions located in front of the crack tip are investigated. The procedure described in Section 3 is used to estimate the CODi- and CODvi-values and the polar coordinates of the particle location with respect to the crack plane. Profiles perpendicular to the crack front are analyzed. In Figure 5.4, the profiles for Inclusion 4 in Table 9.17 are Fig. 5.3. Corresponding stereopaires from the fracture surface of the mild steel St37. 71 σUTS [MPa] N α Steel 37 200 299 426 0.2 7.95 51 JIC [kN/m]
MnS-inclusion r θ MnS-inclusion Section 5 a) b) 72 42 µm Fig. 5.4. Profiles for MnS-inclusion from Fig. 6.3: a) at the moment of the fracture initiation, presented as an example. CODi = 70 µm, b) at the moment of void initiation, CODvi = 42 µm. There is no clear dependence of the CODi- and CODvi-values on the angle θ and the distance r (Fig. 5.5a,b). No influence of the MnS-inclusion diameter on the CODi-values is observed, as well (Fig. 5.5c). But it is seen that the MnS-inclusions with larger diameters are more favorable for void initiation: the CODvi-values clearly decrease with increasing inclusion diameter, d, in the range of 2…8 µm. The maximum interfacial stresses, σ interf max, for MnS-inclusions in the steel St37 are estimated by Eq. 2.3. They vary between 964 and 1478 MPa. A weak influence of the distance, r, and the angle, θ, on the σ interf max -values is found (Fig. 5.6a,b), as well as a strong dependence of the σ interf max-values on the inclusion size. As one can see from Fig. 5.6c, they decrease with increasing diameter of the MnS-inclusion, d.
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MONTANUNIVERSITÄT MONTANUNIVERSIT
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TABLE OF CONTENTS 1. Introduction 5
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7.4.4. The effect of ECAP on the lo
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Section 1 The main results of this
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Section 2 2.2. The influence of the
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Section 2 high strength, fine reinf
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Section 2 etched to mark the inclus
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Section 2 (4.) The specimen prepara
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Section 3 Fig. 3.1. The digital ele
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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 and 38: Section 4 Table 4.3. Mechanical pro
Page 39 and 40: εfr [%] εfr [%] N 16 12 8 4 0 150
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: Section 5 diameter of 2…8 µm and
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
Page 89 and 90: Section 7 It is important that no p
Page 91 and 92: Section 7 between the Rtot and the
Page 93 and 94: Section 7 Fig. 7.8. The fracture su
Page 95 and 96: 10 z [mm] 5 -10 -15 Section 7 0 -20
Page 97 and 98: Section 7 Table 7.3. Data on measur
Page 99 and 100: 8. Summary Section 8 This work deal
Page 101 and 102: Section 8 The effect of the homogen
Page 103 and 104: Table 9.1. Data on stress for Speci
Page 113 and 114: Table 9.11. Data on stress for Spec
Page 119 and 120: Table 9.17. Results of the stereoph
Page 121 and 122: 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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