Effects of unit orientation on the mechanical properties of a die steel with striation units

To improve the mechanical properties of die steels, samples with striation units were processed by laser to create a biomimetic unit-matrix structure. Tensile tests show that the striation unit is of significant effect on the strength and ductility of steel. Interestingly, such an effect is mainly dominated by the orientation of the unit. When the units are aligned along the load direction (unit angle = 0°), the biomimetic sample exhibits the greatest improvement in strength. As the unit angle rises, both the yield strength and ultimate tensile strength are decreased while the ductility is increased. The maximum elongation is achieved in the sample with its units aligned at a 90° angle to the load. To reveal the mechanisms behind these changes, strengthening and toughening characteristics of the striation units in different orientations have been compared and discussed.