25Mn钢冷拔油缸内表面出现局部重皮状缺陷。利用直读光谱法、光学显微镜、SEM和电子探针等分析了25Mn钢冷拔油缸的化学成分、显微组织和缺陷形貌。结果表明:重皮缺陷的产生主要是由于热处理过程中的过热并且保温时间过长导致的,过热导致晶粒粗大,破坏了晶粒原本的致密结构。 Local heavy skin defects appear on the inner surface of 25Mn cold-drawn cylinder. The chemical composition, microstructure and defect morphology of 25Mn steel cold drawn cylinder were analyzed by direct reading spectroscopy, optical microscope, SEM and electron probe. The results showed that heavy skin defects were mainly caused by overheating during the heat treatment and too long holding time. The overheating resulted in coarse grains and destroyed the original compact structure of grains.