In the present work, a high-strength composite steel structure developed by imparting laser surface hardening treatment on a low-carbon low-Manganese automotive steel sheet has been comprehensively analysed. The layered composite steel structure has been successfully developed by re-engineering the surface of the steel using diode laser hardening treatment up to a depth of 250–300 µm through its thickness. Hardness at the treated surface improved by 150% to that of its base due to formation of a mixture of hard phases constituting martensite and bainite along with retained ferrite. Indeed, coupling EBSD technique with Weibull distribution of various phase fractions determined by image quality helped analyse microstructure effectively. The tensile property of the layered composite steel sheet was found to yield significant improvements in both Yield Strength (YS) (40–44%) and Ultimate Tensile Strength (UTS) (19–21%) due to sandwich effect of composite layer constituting hardened layer and soft base accomplished by a strengthening mechanism associated with rule of mixtures concept. In fact, Young’s modulus of the composite steel sheet, determined from slope of tensile stress–strain diagram was found to be convergent with ultrasonic test result. Additionally, the crystallographic texturing effects of the hardened layer and untreated base measured using standard XRD technique re-confirmed their influence on Young’s Modulus and r-bar values obtained.

在目前的工作中，对低碳低锰汽车钢板通过激光表面硬化处理开发的高强度复合钢结构进行了综合分析。通过使用二极管激光硬化处理对钢的表面进行重新设计，层状复合钢结构已成功开发，其厚度可达 250–300 µm 的深度。由于形成了由马氏体和贝氏体以及残留铁素体组成的硬质相的混合物，处理过的表面的硬度比其基体的硬度提高了 150%。事实上，将 EBSD 技术与由图像质量确定的各种相分数的威布尔分布相结合，有助于有效地分析微观结构。由于构成硬化的复合层的夹心效应，发现层状复合钢板的拉伸性能在屈服强度 (YS) (40-44%) 和极限拉伸强度 (UTS) (19-21%)层和软基础通过与混合物规则相关的强化机制实现。事实上，发现复合钢板的杨氏模量，由拉伸应力-应变图的斜率确定，与超声测试结果趋同。此外，使用标准 XRD 技术测量的硬化层和未处理基材的晶体纹理效应再次证实了它们对所获得的杨氏模量和 r-bar 值的影响。