Effect of Cryogenic Trteatment on the Tensile Properties of Carbon Dual Phase Steel

The aim of this study was to evaluate tensile properties low and medium carbon ferrite -martensite dual phase steel, the effect cryogenic treatment at liquid nitrogen temperature (-196 ºC) on its properties. Low steel (C12D) steels (C32D & C42D) were used in work. For each grade, five groups specimens prepared according type heat treatment. first group normalized, second normalized subsequently subjected then tempered (200 for one hour, third quenched from intercritical annealing (760 obtain (DP) fourth fifth both ºC), but forth hour. Mechanical tests carried out which includes, tensile, hardness, as well microscopic examination. Yield strength, ultimate strength ductility DP correlated martensite volume fraction. yield (σy, σu) three steels, higher than those condition, increased after These values, grades, decreased tempering 200 ºC. Tempering 200ºC treatment, causes reappearance yielding point (C32D) while no such a change noticed (C42D) steel. results have shown that hardness grades.