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有两种易切削钢,一种供机械结构使用,另一种供硬切削用的低碳钢,例如SAE12L14。通常的方法是通过添加Pb来改善钢的机械加工性能。然而,钢中的Pb对人体有不良影响。JFE钢铁集团通过控制钢中原有C含量开发了一种不添加Pb的新的易切削钢供机械结构用。利用钢中的石墨析出能获得优良的冷加工性和高的疲劳强度。为了取代SAE12L14,NKK BARS&SHAPES通过使大型硫化物夹杂结晶开发出了不加Pb的新的易切削钢,它是根据计算相图来预测增加S添加量,同时也添加Cr而完成的。
There are two kinds of free-cutting steel, one for the mechanical structure and the other for low-carbon steel for hard cutting, such as SAE12L14. The usual method is to improve the machinability of steel by adding Pb. However, Pb in steel has an adverse effect on the human body. JFE Steel Group has developed a new free-cutting steel that does not add Pb for mechanical construction by controlling the C content in steel. The use of graphite in steel to obtain excellent cold workability and high fatigue strength. To replace SAE12L14, NKK BARS & SHAPES developed a new free-cutting steel free of Pb by crystallizing large sulfide inclusions, which is based on the calculation of a phase diagram to predict the increase of S addition and the addition of Cr.