Due to their high strength, formability and affordable cost, quenched and partitioned (Q&P) steels have shown the potential to reduce the mass of vehicles, thereby decreasing fuel consumption during service. Furthermore, because a lower mass of steel is used in each vehicle, energy consumption associated with the steelmaking process is also reduced. Q&P steels utilize the deformation-induced martensitic transformation (DIMT) of metastable retained austenite to enhance ductility and strain hardening. Accordingly, improvement of mechanical performance is contingent on the ability to precisely control the chemical and mechanical stability of austenite. Considering the multitude of factors that influence austenite stability, optimizing microstructures to delay necking or fracture is challenging, particularly as temperature and strain rate increase. Tensile tests of an intercritically annealed C-Mn-Si Q&P steel were performed over a range of strain rates (10⁻⁴ to 10⁻¹ s⁻¹) to evaluate effects on the DIMT and sheet tensile properties. As strain rates increased from 10⁻⁴ to 10⁻¹ s⁻¹, the uniform elongation decreased from approximately 19 to 14 pct. This reduction in uniform elongation is associated with a decrease in the strain hardening exponent near the onset of strain localization. Based on experimental data from this study and review of previous research, it is postulated that the strengthening contribution of DIMT is controlled by competing effects of: (i) a decreasing chemical driving force for DIMT caused by deformation-induced heat accumulation at higher strain rates and (ii) an increasing number of martensite nucleation sites. This suggests that tailoring austenite stability for specific deformation conditions could enable further optimization of formability and vehicle crash behavior.

由于高强度，可成型性和可负担的成本，淬火和分区（Q＆P）钢已显示出减少车辆重量，从而减少维修期间油耗的潜力。此外，由于在每辆车辆中使用较低质量的钢，因此还减少了与炼钢过程相关的能耗。Q＆P钢利用亚稳态残余奥氏体的变形诱发马氏体转变（DIMT）来增强延展性和应变硬化。因此，机械性能的提高取决于精确控制奥氏体化学和机械稳定性的能力。考虑到影响奥氏体稳定性的众多因素，优化微观结构以延迟颈缩或断裂是一项挑战，特别是随着温度和应变率的增加。在一定的应变速率范围内对C-Mn-Si Q＆P钢进行了临界退火（10）^-4 至10 ^-1  s ^-1）以评估对DIMT和片材拉伸性能的影响。随着应变率从10 ^-4增加到10 ^-1  s ^-1，均匀伸长率从大约19降低到14 pct。均匀伸长率的这种降低与应变局部化开始附近的应变硬化指数的降低有关。根据本研究的实验数据和先前的研究回顾，推测DIMT的增强作用受以下竞争作用的控制：（i）在较高应变速率下，由变形引起的热量积聚导致DIMT的化学驱动力降低（ii）马氏体成核点数量不断增加。这表明针对特定变形条件定制奥氏体稳定性可以进一步优化可成形性和车辆碰撞行为。