Abstract: Fracture causes of ground bolts made of 2Cr13 steel for circulating water pump, were studied by the systematic failure analyzing including chemical composition, mechanical properties, microstructure and so on. The results indicate that not only the C content of the batch bolts is lower, but also the tensile strength, yield strength, hardness and impact property at room temperature are lower than the standard requirements. The fracture analysis shows that the material is very brittle. At the same time, the microstructure analysis shows that the heat treatment process of the 2Cr13 heat-resistant steel is as-annealed, and the comprehensive properties of the as-annealed 2Cr13 heat-resistant steel are obviously lower than those of the quenched and tempered steel. Therefore, the main cause of the bolt fatigue fracture is that the microstructure and properties do not meet the relevant requirements due to the improper heat treatment.

Key words: 2Cr13 steel bolt, fracture analysis, heat treatment, fatigue fracture