Material science problem Describe the microstructure present

Describe the microstructure present in a 1080 aner each heat treat- (a) heat at 820 C, quench to 650 c and hold (b) for 90 s, and quench to 25 C heat at 820 C, to 450 C and hold for 90 s, and quench to 25°C (c) heat at 820 and quench to 25 c 1080 400 Aa 300 200 400 I- T DIAGRAM Tempererere LMIN. IO2 los los 0.5 I 2 5 55 ity for the you have me at

Solution

(a). when quenched to 650c and held for 90s thin layers of both the -ferrite and Fe3C phases are produced; this microstructure is called pearlite.

(b). when quenched to 450c and held for 90s Bainite is formed.The microstructure of bainite consists of ferrite and cementite phases.It is composed of a ferrite matrix and elongated particles of Fe3C

(c) when quenched to 25c martensite is formed.Martensite is a nonequilibrium single-phase structure that
results from a diffusionless transformation of austenite. Its structure is body-centered tetragonal (BCT).