Xu Hao, Jia Zhihong, Lai Qingquan
Key Laboratory for Light-Weight Materials, Nanjing Tech University, Nanjing 211816, China.
Materials Academy, Jiangsu Industrial Technology Research Institute, Suzhou 215131, China.
Materials (Basel). 2025 May 13;18(10):2253. doi: 10.3390/ma18102253.
A good combination of strength and fracture resistance is highly desired for the development of high-strength ferrite-martensite dual-phase (DP) steels for automotive application. But the increase in strength is usually compromised by a reduction in fracture resistance, and the guideline for microstructure optimization remains to be established. This study is dedicated to the DP steels with tensile strength above 1 GPa, and the influences of the equiaxed and fibrous morphologies on the mechanical properties were investigated by both the uniaxial tensile tests and the essential work of fracture (EWF) method. The fibrous morphology is efficient in increasing strength due to the ferrite grain refinement effect. Under uniaxial tension, the fibrous DP morphology does not lead to higher fracture strain. But when evaluating with the EWF method, the fibrous DP steels present a superior fracture resistance, which is attributed to the larger crack tip necking. The interpretation of the fracture resistance measurements was substantiated by the detailed damage observations. Therefore, the fibrous DP concept could provide an efficient pathway to improve the combination of strength and fracture resistance.
对于汽车应用的高强度铁素体-马氏体双相（DP）钢的开发而言，非常需要强度与抗断裂性的良好结合。但是强度的增加通常会因抗断裂性的降低而受到影响，微观结构优化的指导方针仍有待确立。本研究致力于抗拉强度高于1 GPa的DP钢，并通过单轴拉伸试验和断裂基本功（EWF）方法研究了等轴和纤维形态对力学性能的影响。由于铁素体晶粒细化效应，纤维形态在提高强度方面很有效。在单轴拉伸下，纤维状DP形态不会导致更高的断裂应变。但是当用EWF方法评估时，纤维状DP钢表现出优异的抗断裂性，这归因于更大的裂纹尖端颈缩。通过详细的损伤观察证实了对抗断裂性测量结果的解释。因此，纤维状DP概念可以为改善强度与抗断裂性的结合提供一条有效途径。
