一、前言近一年多来,我厂黑心马铁经镀锌后经常出现白脆,给生产造成很大影响。一般以薄小件出现的多,厚大件出现的少,一个产品甚至还出现两种情况,如XGV—3线夹有的齿变了白脆,而与其相连或对称的齿又没有变。金相组织未发生变化,仍为铁素体+团絮状石墨,见图1。未镀锌时断口是黑绒色,组织较细, First, the foreword In the past year or so, my factory black heart horse iron often white crisp after galvanizing, to produce a great impact. Generally appears in thin small pieces, thick pieces appear less, there are even two cases of a product, such as XGV-3 wire clip has teeth white crisp, and its connection or symmetry of the tooth has not changed. Metallographic structure did not change, still ferrite + flocculent graphite, see Figure 1. No galvanized fracture is black velvet, thin tissue,