The natural aging behavior of a low carbon dual phase (DP) steel was studied and the effect of martensite content was taken into account. The enhancement of strength and hardness by aging at room temperature was related to quench aging via the formation of fine precipitates in the ferrite grains. It was revealed that increasing the intercritical annealing temperature diminishes this precipitation hardening effect, which was related to the decreased degree of supersaturation of carbon in ferrite. The maximum quench aging effect was observed by annealing the ferritic-pearlitic steel at a subcritical temperature close to the eutectoid temperature, where the solute carbon content of ferrite reaches the maximum value. However, in contrast to aged DP steels, the tensile stress-strain curves showed yield-point phenomenon. The aging effect was rationalized by the Ashby-Orowan relationship and the effect of the silicon in the chemical composition of the studied steel was discussed.

研究了低碳双相（DP）钢的自然时效行为，并考虑了马氏体含量的影响。通过在室温下时效而提高强度和硬度与通过在铁素体晶粒中形成细小析出物而引起的淬火时效有关。结果表明，提高临界退火温度会降低这种沉淀硬化效应，这与降低铁素体中碳的过饱和度有关。通过在接近共析温度的亚临界温度下对铁素体-珠光体钢进行退火，可以观察到最大的淬火时效效果，在该温度下，铁素体的固溶碳含量达到最大值。但是，与时效的DP钢相比，拉伸应力-应变曲线显示出屈服点现象。