Heterostructured (HS) materials have attracted extensive attention due to their superior mechanical properties. However, there are still many fundamental issues to be solved, like the microstructural evolution process of the hetero-zones during deformation. Here we reported a HS 316L stainless steel generated by exploiting the chemical heterogeneity strategy via thermomechanical processing. The plastic deformation behaviors of the hetero-zones were investigated using three-point bending tests and interrupted tensile tests characterized by electron channeling contrast imaging (ECCI) combined with electron backscattered diffraction (EBSD) techniques. These in situ observations demonstrate the evolution of hetero deformation-induced (HDI) stress field near the austenite/ferrite interfaces in terms of geometrically necessary dislocation (GND) pileups, which can modulate the plastic deformation behaviors of both austenite and ferrite phases. At the early deformation regime, the imposed plastic deformation can be well maintained by the dense and homogeneous activation of slip systems in austenite phases and the stress concentration near austenite/ferrite interfaces can be alleviated by the gradual activation of plastic deformation in the ferrite phases. At the large deformation stage, a progressive twinning-induced plasticity (TWIP) effect caused by the chemical heterogeneity can provide a stable work hardening ability in a broad strain range, which can significantly enhance the ductility. At the late stage of deformation, strain-induced α′-martensite is also triggered, which provides an additional work-hardening ability. The strategy of micro-tuning deformation mechanisms by chemical heterogeneity is versatile and can be applied to many alloys.

异质结构（HS）材料由于其优异的机械性能而引起了广泛的关注。然而，异质区在变形过程中的微观结构演化过程等基础性问题仍有待解决。在这里，我们报道了一种 HS 316L 不锈钢，它是通过热机械加工利用化学异质性策略生成的。异区的塑性变形行为采用三点弯曲试验和间断拉伸试验进行了研究，该试验采用电子通道对比成像 (ECCI) 结合电子背散射衍射 (EBSD) 技术为特征。这些就地观察表明，在几何必要位错 (GND) 堆积方面，奥氏体/铁素体界面附近的异质变形诱导 (HDI) 应力场的演变，这可以调节奥氏体和铁素体相的塑性变形行为。在早期变形状态下，施加的塑性变形可以通过奥氏体相中滑移系的密集和均匀激活来很好地保持，并且奥氏体/铁素体界面附近的应力集中可以通过铁素体相中塑性变形的逐渐激活来缓解。在大变形阶段，由化学异质性引起的渐进孪晶诱导塑性（TWIP）效应可以在较宽的应变范围内提供稳定的加工硬化能力，从而显着提高延展性。在变形后期，应变诱导的α'-马氏体也被触发，这提供了额外的加工硬化能力。通过化学异质性微调变形机制的策略是通用的，可以应用于许多合金。