本文所讨论的问题,通过扫描电镜和能谱对钎杆的典型断口进行分析而观察到钢中有许多细小的氧化物夹杂物(初步确定属铝镁尖晶石类夹杂物),这些氧化物夹杂物有利于疲劳裂纹的形成和扩展,因而是影响55 SiMnMo钢小钎扦寿命的重要因素之一.此外,还通过金相显微镜观察到在由铁素体、奥氏体相间组成的贝氏体中、奥氏体能阻止裂纹的扩展而提高了钢的韧性. The problems discussed in this article were analyzed by scanning electron microscopy and energy dispersive spectroscopy (EDS) to analyze the typical fracture of the drill rod. Many small oxide inclusions (preliminarily identified as Al-Mg spinel inclusions) were observed in the steel. These oxides Inclusion is conducive to the formation and expansion of fatigue cracks, which is one of the important factors that affect the life of small brazing wire of 55 SiMnMo steel.In addition, it is also observed by metallographic microscope that in the microstructure composed of ferrite and austenite, Body, austenite can prevent the expansion of the crack and improve the toughness of the steel.