针对SWRCH22A线材拉拔后再加工M4×30 mm自攻螺丝,成品螺丝发生使用断裂,发现螺丝中心存在孔洞质量问题,对螺丝进行金相组织检测、电镜能谱检测分析.通过对螺丝的不同加工工序产品进行检测分析,发现螺丝中心孔洞是在搓牙工序中产生,分析中心孔洞形成主要是由于钢坯中心疏松经高温轧制后未能完全焊合,在螺丝搓牙过程中受应力影响,细微孔隙扩展、连结,最终形成中心孔洞,导致螺丝断裂.%As to the M4 × 30 mm self tapping screws reprocessed after drawing of SWRCH22A wire, the finished screw was broken. It was found that the screw center had the hole quality problem. And the screw was detected and analyzed by metallographic examination, and the electron microscope. Through the inspection and analysis of the different processing procedures of the screw, it is found that the core hole of the screw is produced in the rolling process. The formation of the center hole is mainly because the billet center fails to completely weld after the high temperature rolling, and is affected by the stress in the screw thread rolling process. The tiny pores expand and connect, and eventually form a central hole, causing the screw to break.
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