导言软钢铁皮下的铜和锡这类残余元素的偏析,是近十年来日益受到重视的问题。这些富集对热加工性的有害影响早有察觉,只是自第二次世界大战后软钢中残余元素含量日益增加,才引起人们对表面热脆性的更大注意。所谓残余元素系指可回收的元素,即是 Introduction Segregation of residual elements such as copper and tin under the mild steel skin is an issue of increasing importance in the last decade. These enrichments have long been aware of the detrimental effects of hot workability, except that increasing levels of residual elements in mild steel since the Second World War have drawn greater attention to the hot surface brittleness. The so-called residual element refers to the recyclable elements, that is