Cr-rich stainless steel sheets exhibit superior corrosion resistance but low ductility, which presents a trade-off between fabrication complexity and performance of the materials in multiple industrial applications, such as marine equipment and microreactors. By transitioning the Cr-rich (30 wt.% Cr) stainless steel component to SS 316 L with a smooth composition gradient in the thickness direction, the intrinsic homogeneous elongation of the Cr-rich layer was increased by 260 % while maintaining the naturally high corrosion resistance (100 %) and retaining most of the strength (more than 80 %). By employing in-situ tensile testing and electron backscatter diffraction analysis, it was revealed that the Cr-rich layer in the gradient structure underwent a profound deformation mechanism, including significant heterogeneous deformation-induced hardening and grain reorientation induced by multiplication and accumulation of geometrically necessary dislocations, in such a way to enable a substantial plastic strain and thereby retarding the occurrence of fracture. The proportion of the Cr-rich layer makes a significant impact on the magnitude of the strain gradient in the gradient specimens, therefore affecting the increment of density of geometrically necessary dislocations. The critical proportion value of the Cr-rich layer is found to be around 22 %. Before and after the critical value the gradient specimens showed different sensitivities to the proportion. This discovery underlines the significance of intrinsic plasticity in low-ductility metals and the role of compositional gradient materials in enhancing strength and ductility.

中文翻译：

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同时具有高强度、高延展性和耐腐蚀性的铬梯度不锈钢：连续硬化机制的深入研究


富铬不锈钢板表现出优异的耐腐蚀性，但延展性较低，这在多种工业应用（例如船舶设备和微反应器）中需要在制造复杂性和材料性能之间进行权衡。通过将富铬（30 wt.% Cr）不锈钢部件转变为在厚度方向上具有平滑成分梯度的 SS 316 L，富铬层的固有均匀伸长率增加了 260%，同时保持了天然的高伸长率。耐腐蚀性（100%）并保留大部分强度（超过80%）。通过原位拉伸测试和电子背散射衍射分析，揭示了梯度结构中的富Cr层经历了深刻的变形机制，包括显着的不均匀变形引起的硬化以及几何必要的倍增和积累引起的晶粒重新取向。位错，以这种方式产生显着的塑性应变，从而延缓断裂的发生。富Cr层的比例对梯度样品中应变梯度的大小有显着影响，从而影响几何必要位错密度的增量。发现富Cr层的临界比例值为22%左右。在临界值之前和之后，梯度样本对比例表现出不同的敏感性。这一发现强调了低延展性金属固有塑性的重要性以及成分梯度材料在增强强度和延展性方面的作用。