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本文运用金相分析、扫描电镜、X射线、MsF-2M应力测试仪等方法对3Cr2W8V穿管机顶头的失效特征和氧化皮结构进行了分析。观察发现:顶头塌鼻子失效是由于鼻部工作温度过高,热强性不够所致;顶头没有好的氧化层是导致粘钢的直接原因;老顶头鼻都二次氧化皮由粘钢层和FeO层组成,它对防止粘钢有利;顶头开裂是由表面氧化磨损和接触疲劳引起的表面损伤,在没有适当热处理及不当材质条件下造成的低周疲劳失效。由此可认为:更换顶头鼻部材质、提高鼻部热强性;预制好的表面防护层;提高轧制区的抗疲劳性能等是提高顶头寿命的关键。实验证实,更换鼻部材质和表面涂层处理以及适当热处理和型腔设计确实能显著提高3Cr2W8V顶头的使用寿命。
In this paper, the failure characteristics and scale structure of 3Cr2W8V pipe jacking head were analyzed by metallographic analysis, scanning electron microscopy, X-ray and MsF-2M stress tester. Observe that: head collapse nose failure due to the nose temperature is too high, the heat is not strong enough; the head is not a good oxide layer is the direct cause of sticking steel; the first nose are secondary oxide from the sticky steel layer and FeO layer, which is conducive to prevent sticking steel; Head cracking is caused by surface oxidation wear and contact fatigue damage caused by the surface, without proper heat treatment and improper material conditions caused by low cycle fatigue failure. It can be considered: the replacement of the nose and nose material to improve the nasal heat strength; prefabricated surface protection layer; improve the fatigue resistance of the rolling zone is to improve the life of the key to the head. Experiments confirmed that the replacement of the nose material and surface coating and heat treatment and cavity design can significantly improve the service life of 3Cr2W8V head.