Using the isothermal transformation diagram for a steel alloy C at 0.45% by weight, It clearly specifies the path and partial and final microstructures (in terms of only the microconstituents present) from a small sample that has been subjected to the following time-temperature treatments. On In each case, consider the sample to start at 845C (1,550F) and to have been held at this temperature for the enough time to have achieved a complete and homogeneous austenitic structure. (a) Quick cool to 450 C (840 F), hold for 10 s, then cool to room temperature. (b) Trace the path to obtain 42% proeutectoid ferrite and 58% coarse pearlite.

900 1600 800 AF A 1400 700 1200 600V 3 1000 500 A 400 50% 800 Mistart) 300 M(50%) 600 MI 90%) 200 400 100 200 0.1 1 10 10 104 105 102 Times Diagrama de transformacin isotrmica para una aleacin acero al carbono al 0.45 %w C. A, austenita; B, bainita; F, ferrita proeutectoide; M, martensita; P, perlita