在用 8.0 mm 70钢硬线冷拉拔后丝材表面出现横向竹节状裂纹。采用化学成分分析、非金属夹杂物和显微组织检验及显微硬度测试等方法对其进行了分析。结果表明,由于材料表层局部存在硬而脆的隐针马氏体组织,导致在冷拉拔过程中因材料的组织与性能差异而出现裂纹。

During the following drawing process,the harding linear steel 70 ( 8.00 mm) appeared transverse bamboo knobs shape crack.Through chemical composition analysis,microstructure and nonmetalic inclusion exammation,and micro-hardness testing,the results showed that,the asymmetry of microstructure,and the hard and brittle acicular martensite,both factors introduced the inconsistent deformation in the drawing process. The inconsistent deformation caused the harding linear steel 70 ( 8.00 mm) transverse bamboo knobs cracking.