STUDY OF THE CRANKSHAFT OF YAMZ-238D1 DIESEL ENGINE THAT FAILED DURING OPERATION

Mechanical and microstructural properties of the crankshaft fragment of YaMZ-238D1 diesel engine are analyzed. The root neck of the crankshaft was studied, since this type of assembly wears out the most during engine operation. The work used materials science methods, including optical electron microscopy to study the microstructure of the material, as well as measurements of the hardness of the working surfaces. As a result, it was found that the average hardness on the working surface of the third root neck is 55...57 HRC; in the core of the third root neck – 178...185 HB. The results of optical electron microscopy showed the presence of a hardened layer about 4.5...4.7 mm thick with a martensitic structure with a smooth transition to the ferrite-pearlite microstructure of the core. It is found out that there are no metallurgical defects in the sample material and the quality of surface hardening is satisfactory. The results of the study can be used to improve technological processes and increase the reliability of internal combustion engines.