| Popis: |
Microstructure modification is an effective approach to improve the mechanical properties of materials. In the present study, expanded graphite (EG) was added in a 20CrMnTi matrix to form pearlite microstructure and proeutectoid cementite after sintering. Mechanical alloying was used to obtain a fine milled mixture with a ball/powder weight ratio of 20:1. After mechanical alloying for 10 h, the milled mixtures with different EG contents were pressurelessly sintered at 1250 °C for 10 min and then hot-pressed at 1150 °C under 30 MPa for 30 min in Ar to obtain dense and modified 20CrMnTi materials. The content of EG has a profound influence on the microstructure and mechanical properties of 20CrMnTi. A high tensile strength of 1088 MPa and a high Vickers hardness of 4.7 GPa were achieved in the 1% EG-modified 20CrMnTi, which were increased by 105% and 28%, respectively, compared with the pure dense 20CrMnTi. The formed fine pearlite and small proeutectoid cementite in the modified microstructure contributed to the improved mechanical properties of 20CrMnTi. |
