In a slurry environment, increasing the hardness and the work hardenin
g index of a steel both provide excellent erosion resistance. In order
to get a steel with higher hardness and work hardening index, the eff
ect of the volume fraction of martensite on these properties in a ferr
ite-martensite dual phase steel having a higher work hardening index c
ompared to similar hardness steels with other microstructures was inve
stigated. Using the theory developed by Tomota et al., the hardness an
d the work hardening indices of some ferrite-martensite dual phase ste
els are calculated. It is shown by the calculation that the steels wit
h 0.2 to 0.7 martensite volume fraction show much higher work hardenin
g indices than other microstructural steels with similar strength. Exp
erimentally, the steel with approximately 0.3 martensite volume fracti
on shows higher work hardening index and twice as much erosion resista
nce compared to similar hardness steels without the dual phase microst
ructure.