Abstract: A conical bolt broke during shaking.The fracture property of the bolt belongs to intergranular brittle fracture through the macroscopic and microscopic observations of the fracture surface.Based on the metallographic structure and Vickers hardness test results,it is determined that the hardness of the bolt is related to the absence of ferrite in its structure.Combining its energy spectrum,fracture properties,and tempering temperature,Infer that the bolt may have temper embrittlement.It is proved that the sample without ferrite has greater brittleness after tempering at 570℃,and the fracture surface is intergranular brittle fracture by artificially breaking the 14Cr17Ni2 stainless steel sample with and without ferrite tempered at 570℃,the fracture surface of the sample with ferrite is mainly quasi cleavage.Finally confirmed the fracture cause of the conical bolt was due to the interaction of the tempering temperature being in the tempering brittleness range and no ferrite in the structure.