hardness limit

例句：

1. 1. Thematerial has a hardness limit of 60 on the Rockwell scale.
   该材料的洛氏硬度极限为60。
2. 2.The steel is used in construction due to its hardness limit.
   由于其硬度极限，这种钢被用于建筑。
3. 3.The hardness limit of the alloy was determined by testing samples under various conditions.
   通过在不同条件下测试样本，确定了合金的硬度极限。