Research on grain size control of C55E+N forgings for large intermediate shafts

In view of the problem that coarseness is very easy to occur in C55E+N intermediate shaft forging,austenite coarsening tests at 820～980℃and normalizing tests at 770～920℃were carried out to study the critical temperature leading to severe grain coarsening and the influence of different normalizing temperatures on the microstructure of C55E+N.The results show that the C55E+N grains are coarsened seriously when the temperature is heated to 950℃.When the normalizing temperature is 860℃,the mesh ferrite can be eliminated while the grain is refined,and the good microstructure can be obtained.Based on the research results,the forging and normalizing process of intermediate shaft are improved,and the problem of detecting coarse crystals is effectively solved.