Question

Alloying elements play a critical role at achieving special properties and characteristics in iron. strengthening. precipitation strengthening and grain refinement as well as element of iron, and it exists primaniy as a form of carbide after reacting with iron or other alloying elements. The theme of the heat treatment of iron alloys is to adjust the distribution of C and carbide particles. This is also the key to understanding and designing the heat treatment of iron alloys. They cause solid-solution other favorable functions. C is the principal alloying 11. The following figure is the TTT diagram of a hypoeutectic steel, and the pink line is the cooling history. Please describe the microstructure at each of the six points indicated along the line. (15 points) 900 800 700 Y-Fe+a-Fe 6002 50 100 Pearlite 500 D 400 9 300 200 100 Bainite Mso 1-min 1 hour 0.1 1 10 102 103 10105 Time (s)

Answer 1

ine stuctute stale condtion ( Austen te) 2 Rapdcoolng -to e metastable Austeite cn te (Fel)in -3 see FOSmation evite FC Competion ocoTse enbte shich contain d- Peivite 6 Retained Ausenite hese Comdetel Conner led hee Cito