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

2. 0.2 µm

3. with carbides

4. Carbide-free alloys wt %

5. 1 µm

6. Very poor toughness!

7. 50 µm

9. T-zero curves

10. 50 µm

12. 0.4C-3Mn-2Si 0.4C-4Ni -2Si 0.2C-3Mn-2Si Impact Energy 2001000-100-200 0 10 20 30 40 50 60 70 Test temperature / °C

14. 20 µm

16. 120010008006004002000 Pearlite Martensite Bainite kilocycles to Crack Initiation Yates, Jerath

19. Advances in carbide-free bainitic steels 2500200015001000 20 40 60 80 100 120 140 160 180 Ultimate tensile strength / MPa Fracture toughness / MPa √m 18 wt% Ni maraging steel QT

20. an apple weighs 1 Newton 1 m = 1 Pa

21. Cooking temperature? 180 to 220 °C

22. 200 °C for 20 days Caballero, Mateo & Bhadeshia 2.5 GPa

23. 50 nm     

24. 20 nm     

25. Low temperature transformation: 0.25 T/T m Fine microstructure: 20 nm thick plates Carbide-free Designed using theory alone Typical mechanical properties:

27. Very Strong, Low Temperature Bainite 2500200015001000 20 40 60 80 100 120 140 160 180 Ultimate tensile strength / MPa Fracture toughness / MPa m 1/2 18 wt%Ni maraging steel QT