The tip of the screw driver has been made of hardened steel which has been ground to provide a long life and a precise carburettor set-up. 尖端的螺丝刀已经取得了淬硬钢已地面提供一个长期的生活和一个确切的化油器的设立。
After niobium microalloying for high carbon steel,the mechanical properties of wire rods was improved. 铌微合金化处理后高碳钢线材的力学性能得到了改善。