Dual-phase (DP) steels are a subset of high-strength, low-alloy steels that exhibit a unique balance of strength and ductility due to their dual microstructure of ferrite and martensite. This study investigates the effects of varying martensite volume fractions on the mechanical properties of DP steel by preparing samples with martensite contents from 20% to 50%, achieved through intercritical annealing at temperatures between Ac1 and Ac3, followed by quenching in ice-brine. The mechanical properties of these samples were analyzed using optical microscopy, hardness tests, and impact toughness measurements. Results reveal that increasing the martensite volume fraction enhances both hardness and impact toughness, indicating that adjusting heat treatment parameters can optimize DP steels for strength-critical applications. This study provides insight into the microstructural factors influencing DP steel properties and highlights effective processing routes for tailoring material performance............. Keywords: ......Dual-Phase Steel, Microstructure, Heat treatment, Mechanical properties.