Abstract：Batch fracture of cylinder head bolts for a certain type of diesel engine occurred during the installation. The causes of bolt fracture were analyzed by macroscopic morphology analysis, scanning electron microscope analysis, metallographic structure detection, mechanical properties detection, installation process simulation, and chemical composition detection. The results showed that the bolt fracture mode belonged to the overload fracture under torsional load, and the main reason for the bolt overload fracture was the unreasonable installation process of bolt. It led to too much axial load, which exceeded the strength limit of bolt. Combined with laboratory simulation installation results and field assembly conditions, the installation process of cylinder head bolts was improved, and a reasonable installation process was established.
2021, Vol. 39 
