Linking Processing Microstructure and Property Models individual phases

“Linking Processing, Microstructure and Property Models”

individual phases g g a composite action a transformation plasticity a 20 nm

Carbon supersaturated plate Carbon diffusion into austenite and carbide precipitation in ferrite Carbon diffusion into austenite Carbide precipitation from austenite UPPER BAINITE (High Temperature) LOWER BAINITE (Low Temperature)

Swallow and Bhadeshia, 1996

Peet, Babu, Miller, Bhadeshia, 2004

Okabayashi and Tomita

1 µm

brazing data from Bredzs & Case

Young & Bhadeshia

Young & Bhadeshia

Young & Bhadeshia

hard phase elastic, soft phase plastic average plastic strain stress, hard flow stress, soft elastic constants fraction hard

hard phase yields at a lower stress than in homogeneous sample soft phase yields at a higher stress than in homogeneous sample

g g a a a 20 nm

transformation-induced plasticity 50 mm

general invariant-plane strain simple shear uniaxial dilatation s s d 1 1 d 1 s=0. 26 d=0. 03

Bhadeshia, 1982

polycrystalline austenite 50 mm s Bhadeshia, 1982

s z 3 d z 1

u v

Sakuma et al. (1991)

Need to improve mechanical stability of austenite

Very poor toughness!

50 µm

Impact Energy 70 60 0. 4 C-3 Mn-2 Si 0. 4 C-4 Ni -2 Si 0. 2 C-3 Mn-2 Si 50 40 30 20 10 0 -200 -100 0 Test temperature / °C 100 200

Hard Bainite 180 Fracture toughness / MPa m 1/2 160 18 wt%Ni maraging steel 140 120 100 80 60 40 20 1000 QT 1500 2000 Ultimate tensile strength / 2500 MPa

g g a a a 20 nm

2500 MPa, 40 MPa m 1/2

Scifer, 5. 5 GPa with ductility! Kobe Steel

1 Denier: weight in grams, of 9 km of fibre 50 -10 Denier Scifer is 9 Denier

700 Temperature/ o. C 600 500 400 BS ~ 350 o. C 300 200 MS = 120 o. C 100 0 1. E+02 1. E+04 Time / s 1. E+06 1. E+08

thank you !