Effect of reticular non-metal inclusions on impact toughness of WR13 tool and die steels

To explore the influence of the continuous inclusion network on the impact performance of WR13 tool and die steels, the WR13 alloy powders were prepared by argon atomization and formed by hot isostatic pressing sintering. Taking the imported low-oxygen-content WR13 alloy powders (mass fraction) and the corresponding ingots as the contrast, the microstructure and mechanical properties of the WR13 alloy powders and the corresponding ingots were carried out by oxygen-nitrogen-hydrogen analyzer, laser particle size analyzer, scanning electron microscope, and pendulum impact tester. The results demonstrate that the formation of the reticular inclusions is closely related to the coupling effect between alloy powder particle size and oxygen content. The reticular inclusions formed by Al₂O₃ particles are observed exclusively in ingots prepared by small-sized and high-oxygen-content alloy powders. These inclusions disrupt the metallurgical bonding between the substrates and induce the stress concentration due to the deformation mismatch with the substrates, serving as the primary initiators of crack formation. Comparative results show that, the ingots without continuous reticular inclusions achieve the impact energy of (17.5± 3.08) J, whereas those containing such inclusions exhibit the reduced impact energy of (7.9± 3.97) J, with significant fluctuations. Fracture images reveal that, the larger the inclusion size and the greater the inclusion quantity in the ingots, the easier it is for the cracks to initiate and propagate, ultimately leading to the decrease in impact performance and poor stability of the ingots.