This work studied the microstructural characterization and
mechanical behavior of low manganese Austempered Ductile
Iron (ADI), with a view to improve the properties of iron and
to increase the areas of applications. Three sets of ductile iron
of specified composition were machined from Y-blocks to
tensile and hardness pieces. The samples were preheated at
350 0C for 1hr and austenitised at 900 0C for 1hr in salt bath
furnace. The three sets of samples were immediately
austempered in the austempering salt bath furnace at uniform
austempering temperatures of 300 0C, 350 0C and 400 0C for
90, 120 and 150 minutes; each sample for each temperature
window. All sets were prepared for metallographic
examination; tensile and hardness tests were carried out. The
results showed that maximum hardness, tensile and yield
strength were obtained at austempering temperature of 350 0C
and at 150 minutes. At 300 0C and 350 0C, it was noticed that
the hardness and strength increase with austempering time.
The optimum tensile strength was 1300 MPa at 350 0C after
austempering for 150 minutes. In conclusion the austempering
operation has a significant effect on the mechanical and
microstructural properties of ADI