0.2 µm

Jae Hoon Jang, In Gee Kim 7

1 µm

Fine structure Retained austenite: TRIP effect no ductile-brittle transition barrier to hydrogen No cementite Small concentration of C in ferrite

50 µm

14

50 µm

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

20 µm

Yates, Jerath, Bhadeshia 22

Kevin Sawley: 90 million gross tonnes of traffic on curve

24

25

Advances in carbide-free bainitic steels 20 40 60 80 100 120 140 160 180 18 wt% Ni maraging steel Fracture toughness / MPa √m QT 2500 2000 1500 1000 Ultimate tensile strength / MPa