The effects of heat treatment parameters on the mechanical properties on high strenght dual phase steels

Steels are commonly used especially in automotive industry. In addition, high strength dual phase steels that have higher formability are more popular in industry. In this study, dual phase steels are produced by inter-critical annealing method and the effects of process parameters (annealing temperature, annealing time and cooling medium) on the microstructure and mechanical properties of dual phase steels were investigated. and annealing duration of intercritical annealing heat treatment on mechanical properties of dual phase structure are investigated. Tensile and v-notched impact tests are applied to demonstrate the effect of parameters on mechanical properties. The relationship between volume ratio of martensite and ultimate tensile strength is presented in accordance with microstructure examination. As a result of the study, the strength properties of AISI 4340 steel in ferrite-perlitic structure are improved and equivalent values of toughness are obtained. It was revealed that there is no linear relation between volume ratio of martensite and ultimate tensile strength.