Mechanical property and its application of steel sheets with strength gradient through sheet thickness direction

作为控制压成形钢板力学性能的一种新方法，研究了沿钢板厚度方向连续改变材料强度的有效性。本研究通过控制不锈钢的氮浓度分布，获得表面或中心强度最大的“强度梯度钢板”，并对这些试样的力学性能进行了评价。结果发现，即使拉伸强度相同，弯曲强度也会随强度梯度而变化。这表明用这种方法可以改善钢板的机械性能。

As a new approach to control mechanical properties of steel sheets for press forming, the effectiveness of changing material strength continuously through sheet thickness direction was investigated. In this study, nitrogen concentration distribution was controlled for stainless steel to obtain 'strength-gradient steel sheets' with a maximum strength at the surface or in the center of the sheet, and then the mechanical properties of these specimens were evaluated. As a result, the bending strength was found to be varied depending on the strength-gradient even when the tensile strength is identical. This suggests that it would be possible to improve mechanical properties of steel sheets for press forming by this method.