Effect of Smelting Process on the Microstructure and Properties of 23MnNiMoCr54 Mining Round Chain Links

Through Rockwell hardness testing， EBSD， XRD， TEM characterization and other methods， the differences in hardness and microstructure between German and domestic 23MnNiMoCr54 chain link steels were revealed. The results show that the German chain link has higher residual elements Cu and N due to the all-scrap-electric furnace smelting process， with an average hardness of 41.32HRC and a range of only 0.85HRC， showing the highest average hardness and the smallest hardness fluctuation.The high N content leads to an increase in the density of precipitated phases， which refines the original austenite grains to 13.66 μm through the Zener pinning effect and increases the proportion of high-angle grain boundaries to 38.3%. These factors synergistically hinder the movement of dislocations， resulting in the highest hardness of the German chain link.During the medium-frequency quenching process， after the surface temperature of the workpiece exceeds the Curie temperature， the surface eddy current density increases and the austenitization temperature becomes higher， leading to the coarsening of the original austenite grains and an increase in dislocation density at the edges of both German and domestic chain links. This study provides a theoretical basis for the upgrading of smelting processes and heat treatment technologies for domestic mining chain links， and it is of great significance to promote the process of domestic substitution of key parts and components of mining equipment.