The improvement in the combination between strength and ductility of austempered ductile iron with dual matrix structure was investigated in two ductile irons having different silicon contents, namely 2.6 wt% and 4.0 wt%. The structure was produced in a thermo-mechanical simulator, equipped with a dilatometry system. The effect of silicon content on the transformation kinetics and mechanical properties was studied. For both ductile irons, the influence of introducing ferrite into the matrix on the structure development and mechanical properties was investigated and compared to those of completely ausferritic matrix. Increasing the Si-content widened the intercritical region and shifted it to higher temperature range. The former effect renders the intercritical annealing process more controllable. The introduction of the ferrite phase accelerated the ausferrite transformation kinetics and improved both the ductility and the formability index (ductility × ultimate strength), while both yield and ultimate strength declined.

中文翻译：

---

热机械处理对不同硅含量的双相矩阵ADI结构和性能的影响

在两种硅含量分别为2.6 wt％和4.0 wt％的球墨铸铁中，研究了具有双基体结构的奥氏体球墨铸铁的强度和延展性之间的组合改善。该结构是在装有膨胀计系统的热机械模拟器中生产的。研究了硅含量对转变动力学和力学性能的影响。对于这两种球墨铸铁，研究了将铁素体引入基体中对组织发展和力学性能的影响，并将其与完全奥氏体基体的影响进行了比较。Si含量的增加拓宽了临界区，并将其转移到更高的温度范围。前者的作用使得临界退火过程更可控。